Pre-Transfusion Testing and Antibody ID

Question 1

A patient has a positive antibody screen and a positive antibody identification panel. All tested cells are positive 3+ at the AHG phase of reactivity, including the autocontrol. The patient has never been transfused or pregnant.

Which adsorption technique would you use to complete the case?

a. cold alloadsorption
b. cold autoadsorption
c. warm alladsorption
d. warm autoadsorption

Answer 1

d. warm autoadsorption

The antibody reacts at the AHG phase of testing, which indicates a warm antibdoy and the adsorption should take place at 37 C.

Since the patient has not been transfused or pregnant in the last 3 months, an autoantibody is suspected and the patients own autologous cells can be used to conduct the adsorption. The autoadsorption will act to “Soak Up” the autoantibody and leave behind the serum that can then be used to screen for additional antibodies (the “left behind” serum is known as “adsorpbed serum”).

Performing an autoadsorption over an alladsorption is preferred when possible because the patient’s own cells do not run the risk of adsorbing out any clinically significant antibodies.

Question 2

You identify an RBC alloantibody in a patient. Which antibody would be eligible for antibody screens and crossmatches using the prewarm technique?

a. anti-E reacting at 37 C and AHG

b. anti-S reacting at AHG using LISS and PEG

c. anti-K reacting at PEG AHG

d. anti-M reacting at immediate spin, 37 C and weak at the AHG phase.

e. anti-M reacting at the AHG phase

Answer 2

d. anti-M reacting at immediate spin, 37 C and weak at the AHG phase.

Anti-M is usually an IgM cold-reacting antibody. When testing is performed at IS, 37 C, and AHG, the IgM pentamer can bind strongly and carry through all phases of testing. Once an antibody in this category is identified, you can use the prewarm technique to provide compatible RBCs for transfusion to the patient if the antibody may be causing interference at the AHG phase. The prewarm technique allows you to provide these RBCs without phenotyping the RBCs for the corresponding antigen against the patient antibody.

If the antibody in question still shows agglutination at the AHG phase of testing using the prewarm technique, you must provide the patient with RBCs that are antigen typed for the corresponding antigen against the patient antibody.

anti-M, which is usually IgM, may contain an IgG component that can cause this problem.

NOTE THE SECOND SENTENCE ABOVE! This advice applies after the antibody is identified! It is usually poor practice to simple “PreWarm” an unknown cold-reacting antibody without having an idea of what it is. Some cold-reacting antibodies can have wide thermal amplitudes an cause significant hemolysis, so the PreWarm technique should not be used as a substitute for proper antibody identification.

Question 3

What is the purpose of Coombs’ controll cells?

a. To ensure that AHG reactions are not false-negatives
b. to ensure that washing removed all unbound antibody
c. to ensure that AHG was not omitted or inactivated.
d. All the above

Answer 3

d. All the above

Question 4

What is an elution?

a. A technique used to dissociate IgM or IgG antibodies form sensitized RBCs.
b. A technique used to determine if a patient is a sickler.
c. A technique used to reduce the zeta potential inhancing antigen binding.
d. none of the above.

Answer 4

a. A technique used to dissociate IgM or IgG antibodies form sensitized RBCs.

Question 5

When performing the elution procedure, what is the solution containing the recovered antibody called?

a. Neutralized serum
b. The buffer
c. The eluate
d. Absorbed serum

Answer 5

c. The eluate

Acid is added to the red cells which will elute off the antibody. Once antibody has been eluted, the red cells are discarded and a buffer added to make the eluate containing the antibodies to make it an opitmial pH for testing,

Question 6

The process of removing antibdoy from serum by combining serum sample with appropriate red cells under optimal conditions is called:

a. Elution
b. Absorption
c. Enzyme treatment
d. Sensitization

Answer 6

b. Absorption

The target antibody will be removed from the serum and attach to the red blood cells

Question 7

Routine pre-transfusion testing consists of all of the following except:

a. ABO typing
b. Rh typing
c. Antibody Screen
d. DAT

Answer 7

d. DAT

Autocontrol and DATS are not required per AABB Standards and are performed per each facilities procedures.

Question 8

What is the most common use of adsorption?

a. Removal of plasma protein from patient serum.
b. Removal of alloantibody from patient serum.
c. Removal of autoantibody from patient serum.
d. Removal of drug-induced antibody form patient serum.

Answer 8

c. Removal of autoantibody from patient serum.

The most common use of an adsoprtion is to remove autoantibodies from serum that could be hiding clinically significant alloantibodies.

Other uses can include removing a specific alloantibody to allow for performing rule-outs or rule-ins for other alloantibodies or differential adsorptions/elutions to identify the specificity of an antibody (ex. G differential).

Anti-drug antibodies cannot be adsorbed out of the serum; some monoclonal drugs that attach to specific CD proteins may be able to be absorbed out but this is not usually the best method.

Question 9

In what circumstance would an alloadsorption be performed?

a. Warm autoantibody in serum
b. HDN
c. Multiple antibodies in serum
d. Hemolytic transfusion reaction

Answer 9

c. Multiple antibodies in serum

Removing an antibody, such as anti-k that is against a high frequency antigen, can allow for easier detection of other alloantibdoies and to rule out other common clinically significant alloantibodies.

Question 10

A patient with anti-K was crossmatched with 4 units of ABO/Rh compatible, K-negative donor blood. The units were compatible in all phases of testing. After the antiglobulin phase. IgG sensitized control cells were added and a 2+ reaction was noted. The proper interpretation of this 2+ reaction is that the:

a. cell washing was adequate
b. Crossmatch was performed properly
c. Patient’s serum was added
d. Crossmatched units were K Positive
e. all of the above

Answer 10

a. cell washing was adequate

Coombs control cells only tell you if:

1. The RBCs were washed properly
2. The anti-human globulin was added
3. The anti-human globulin worked properly (was not neutralized)

It does not tell you if the entire test was performed correctly. It cannot detect, for example, If any reagent (serum, enhancement, etc.) was omitted. If the correct check cells were used, or if the testing was performed at the right temperature.

Question 11

Which of the following antigens are not required to be on reagent screening cells?

a. Jsa
b. D
c. Fyb
d. C

Answer 11

a. Jsa

Jsa is a low frequency antigen and is not required by the FDA to be on the selected cells. The D, C, and Fyb antigens are required by the FDA to be on the selected cells and panels.

Question 12

In what test might rouleaux cause an interference?
a. DAT
b. Forward ABO typing
c. Reverse ABO typing
d. Rh control

Answer 12

c. Reverse ABO typing

Rouleaux is an issue found in the patient’s serum. Reverse ABO testing tests with serum so rouleaux can interfere with testing.

The DAT forward ABO and Rh control are all testing the patient’s red cell antigens and not the patients antibodies (serum).

Question 13

In interpreting an antibody screen, which of the following questions might be asked to decipher the class of antibody?

a. Is the autologous control positve or negative?
b. Is hemolysis present?
c. In what phase did the reaction occur?
d. Is rouleaux present?

Answer 13

c. In what phase did the reaction occur?

A reaction at colder temperatures (4 C, RT, IS, 22 C) or warmer temperatures (37 C/AHG) will give you an idea as to what class (IgM or IgG) the antibody belongs to.

If your auto control is positive or negative, the phase where the control is positive at will still need to be evaluated to determine if it is a cold or warm antibody.

Question 14

Why are screening cells group O?

a. To prevent interference from anti-A and anti-B antibodies in patient serum
b. To prevent interference with A and B antigens on patient cells
c. Because group O cells are easier to acquire in random populations.
d. Because of group O cells contain antigens to clinically significant antibodies.

Answer 14

a. To prevent interference from anti-A and anti-B antibodies in patient serum

Screening and panel cells are group O because a group O person does not have A and B antigens. This allows for patients of all blood groups to be tested with the same panels (easy to remember because group O is the universal RBC donor for this same reason). If you are testing a patient that is group A, B or AB, their naturally occurring anti-A and anti-B will not being to the screening/panel cells.

Question 15

Why is it important for screening cells to be from individuals who have homozygous expression of antigens?

a. Homozygous expression is directly related to clinically significant antibodies.
b. Stronger reactions are seen with heterozygous cells than with homozygous cells.
c. Weakly reacting antibodies may not agglutinate heterozygous cells.
d. All of the above

Answer 15

c. Weakly reacting antibodies may not agglutinate heterozygous cells.

All other statements are false. Homozygous expression is not directly related to clinically significant antibodies, nor do you see stronger reactions with heterozygous cells than with homozygous cells. Remember homozygous cells have a stronger expression than heterozygous cells.

Double dose is the correct term vs homozygous and single dose vs heterozygous: however. like “anti-Kell” instead of anti-K or -K1, some terminology just sticks around in blood bank. Be aware when you’re looking at a panel and the reagent cell appears like it could be from someone of black ethnicity, it’s possible their duffy antigen may appear to be homozygous but really it is only a single dose due to the GATA mutation.

Question 16

Serum containing anti-D, -C and -G was adsorbed onto a r’ red cell.

An eluate prepared from the r’ cells would contain which antibodies?

a. anti-G
b. anti-D and anti-G
c. anti-C
d. anti-C and anti-G

Answer 16

d. anti-C and anti-G

The serum contains all three antibodies: -D, -C, and -G and is going to be absorbed onto r’ cells. Recall r’ cells are D-,C+ and G+. Because the D antigen is not present, anti-D will remain in the patient’s serum but anti-C and -G will be absorbed onto the r’ red cells.

An elution will remove the absorbed antibodies, which means the eluate will contain anti-C and anti-G. Remember the G antigen is present on D AND C positive cells, so if the eluate was tested with a panel, reactivity would still be observed with d and C positive red cells.

Question 17

In the direct antiglobulin test (DAT), the antiglobulin reagent is used to:

a. detect pre-existing antibodies on erythrocytes
b. measure antibodies in a test serum by fixing complement.
c. precipitate anti-erythrocyte antibodies
d. mediate hemolysis of indicator red blood cells by providing complement.

Answer 17

a. detect pre-existing antibodies on erythrocytes

In the DAT, the RBCs are washed then the anti-human globulin reagent (AHG) is added followed by the tube being spun then read for agglutination. This test detects the presence of antibodies which were already bound to the surface of the red cell in vivo (in the patient’s body.

Contrast this with the indirect antiglobulin test (IAT) in which the RBCs are incubated first with patient serum or commercial reagent in an attempt to bind antibodies to the RBCs, then washed, AHG added, spun and read. The IAT detects the presence of antibodies which were bound in-vitro (outside of the patient’s body in the test system)

Question 18

What is the most appropriate control for a positive direct antiglobulin test?

a. check cells and antihuman globulin
b. patient cells and antihuman globulin
c. check cells and saline
d. patient cells and saline

Answer 18

d. patient cells and saline

When all of the DAT tests are positive, it is prudent to test a DAT control to be sure that the patient cells are not spontaneously agglutinating in the test system. Therefore, test the patient cells in a neutral medium (one that does not contain antibodies).

Of those listed, the best choice is patient cells and saline. Some facilities will test patient cells in diluted albumin, which is acceptable as well.

Question 19

You have a serum sample which has anti-e, anti-Fya, and anti-JKa. The goal is to remove the anti-Fya specificity from the serum sample. Which cell below is the best choice to use as an absorbing cell?

a. e+, Fy(a)-, Jk(a)+
b. e-, Fy(a)-, Jk (a) -
c. e-, Fy(a) +, Jk (a)-
d. e-, Fy(a)-,Jk(a)+

Answer 19

c. e-, Fy(a) +, Jk (a)-

To remove the anti-Fya forma mixture of anti-e, antiFya, and anti-Jka, pick a cell that has only the Fya antigen and lacks the e and Jka antigens. Remember that the question said the goal was to remove the anti-Fya specificity only.

The other choices would either remove an additional antibody or leave the anti-Fya behind.

Question 20

A patient is tested, and the following results are obtained:

ABO/RH: O Positive
Antibody Screen:

Screening Cell IAT Check Cells

SCI 2+ NA
SCII 2+ NA
SCIII 2+ NA
Autocontrol 2+ NA

Of the choices below, which tpe of eluate is the best choice for the next phase of testing?

a. Freeze-Thaw
b. Cold-Acid
c. Ether
d. Heat (56 C)

Answer 20

b. Cold-Acid

Of the eluate procedures listed, the cold acid is the best choice. An example of the cold acid is the ELUKIT, a commercially made eluate kit. From the screening cell results, it appears to be a warm autoantibody of broad specificity. Choose an elution procedure that givevs a good recovery for this type of antibody.

Freeze-Thaw and Heat eluate techniques are good for ABO antibodies, but not for other blood group antibodies.

Ether is a hazardous substance. While it does offer a good recovery of warm reacting antibodies, it’s hazards far outweigh its technical benefits.

Question 21

A patient who has not been transfused within the past three months has the pollowing pre-transfusion results:

ABO/Rh: O Positive

The antibody screen was positive, and so an antibody ID panel was tested, and the results are below.

Cell AGT CC

1 2+ NT
2 2+ NT
3 2+ NT
4 2+ NT
5 2+ NT
6 2+ NT
7 2+ NT
8 2+ NT
9 2+ NT
10 2+ NT
11 2+ NT
Auto 2+ NT

Which choice below is the BEST step (that will give you new and helpful information) to perform next?

a. DAT
b. Elution
c. Autoadsorption
d. Test cells that are negative for high frequency antigens

Answer 21

c. Autoadsorption

This patient most likely has a broad spectrum autoantibody in the serum based on the results given. When selected the BEST step to perform next, you would select a test that will give you the most new and helpful information.

If you perform a DAT, it is likely it will be positive but what does that really tell you that is new? We already know the autocontrol is positive and the positive DAT is expected in this case.

If you perform an elution next, the likely result is that all cells will be positive in the panel. Again, what does that really tell you? If we are seeing a broad spectrum autoantibody in the serum, then it is likely that it is also in the eluate. Especially if you are low on sample and have to choose between an eluate or autoadsorption, the adsoprtion will be the most beneficial. If there is enough sample, an elution still be done to help confirm the WAA, but wont help transfusing the patient and determining if there’s an alloantibody present.

Testing the serum against selected cells that are negative for high frequency antigens won’t help much at this point since the autoantibody will likely react positive with all cells tested. The patient has not recetly been transfused so a HTR to a high incidence antibody is not suspected.

Therefore sicne the patient has not been recently transfused, we could do an autoadsorption procedure, This would remoev the autoantibody and leave behind any alloantibodies. It is important that we know if any clinically significant alloantibodies are present. Dong an autoadsoprtion will give us the “most bang for the buck”.

Question 22

If a patient is found to have a broad spectrum cold autoantibody, which of the following techniques below would be helpful in diminishing the effects from the cold auto within the testing system?

a. pre-warmed techniques
b. use of anti-IgG monospecific AHG reagent
c. cold adsorption (all or auto)
d. all of the above would be helpful

Answer 22

d. all of the above would be helpful

Cold reacting autoantibodies can be a nuisance in the blood bank. They can interfere iwht testing and make detection of clinically significant alloantibodies more difficult. All of the procedures listed can be used to reduce the likelihood of detecting the cool autoantibody.

Question 23

A patient is on high levels of penicillin delivered via an IV line. He has strongly positive DAT. The serum antibody screen shows negative reactions with SCI, SCII, and SCIII. The autocontrol is positive at AGT phase. The citric acid elution is negative when tested with screen cells and ABO reverse cells. What additional cells could be tested with the serum and eluate in an attempt to identify the cause of the positive DAT?

a. cord cells
b. Rh null cells
c. Drug coated cells
d. Panel of cells positive for low frequency antigens

Answer 23

c. Drug coated cells

In this vase the patient has been on a large doses of IV pnicillin which should always bring to mind the possibility of DIIHA. High dose penicillin can cause the patient to make antibodies to the drug itself. The high levels of drug coat the patient cells with drug haptens. The anti-drug antibody binds to the drug which is attached to the patient’s RBCs causing the RBCs to be coating with antibody and drug. (See Tech Man figure 20-2 for schematic)

Testing the patient serum and eluate with drug coated cells can help ID this anti0Drug antibody. The antibody is directed against the specific drug, not RBC components. Therefore, the specific drug must be present in the test system. IV penicillin in large doses is a classic example of this anti-drug mehanism.

Question 24

Anti-ceftriaxone antibodies are known to cause intravascular hemolysis via which drug-anti-drug mechanism?

a. Drug hapten
b. Membrane modification
c. Immune complex
d. Warm autoantibody production

Answer 24

b. Membrane modification

Question 25

A patient has been on large doses of alpha-methyldopa (trade name Aldomet) for a extende period of time. The patient presents with the following pre-transfusion testing results: ABO = B Pos SCI = 2+ SCII = 2+ SCIII = 2+ Autocontrol = 2+ Hemoglobin = 7.0 This scenario represents a drug induced hemolytic anemia due to which mechanism? a. Drug hapten b. Membrane modification c. Immune complex d. Warm autoantibody production

Answer 25

d. Warm autoantibody production Alpha Methyldopa is a classic cause of warm autoantibody production. Although the exact mechanism has not been proven, it has been postulated that the drug alters the T-suppressor cells which in turn allows the body to produce antibody against itself. Unlike the other drug mechanisms, once the warm autoantibody is produced it will react with all cells tested, not just those coated with drugs.

Question 26

A patient has a compensated hemolytic anemia due to cephalosporin, acting according to the membrane modification system. This patient's DAT results are below: Poly = 2+ IgG = 2+ C3 = 2+ Control = 0 An eluate is performed and tested against panel cells, ABO reverse cells and cephalospprin coated cells. What is the most likely pattern of reactivity that we will see with the eluate? a. All cells react 2+ b. Panel is negative. Reverse cells are negative. Drug coated cells are positive. c. Panel is positive. Reverse cells are negative. Drug coated cells are positive. d. All cells are negative.

Answer 26

d. All cells are negative. In membrane modification, proteins non-specificity adhere to the RBCc membrane. The RBC membrane is modified by the drug and acts like a magnet to randomly attach protein molecules. There is no antibody production that occurs. Therefore, the elaute will be negative with all cells tested as well as reagent cells where the membrane has not been modified.

Question 27

The best indicator of clinical effectiveness of granulocyte transfusion is: a. Increased reticulocyte count b. Resolution fever or other signs of infection c. Decreased production of immunoglobulins d. Increased granulocyte count

Answer 27

b. Resolution fever or other signs of infection When granulocytes are transfused, they go right tow work at fighting the infection, and as such the numbers of granulocytes may not increase. The best indicator of the success of the transfusion, is that the patient begins to show sings of recovering from the infection.

Question 28

A group A positive patient was transfused 25 group O platelets. Pretransfusion testing revealed no unexpected results. The day after the transfusion, the patient was weakly positive and showed mixed field agglutination. Which of the choices is the most probably explanation of these results? a. Patient had a positive DAT that was not detected in pretransfusion testing b. Isoagglutininins in patient serum coated transfused platelets c. Isoagglutinins in platelet's serum coated patient cells d. Patient is developing a warm autoantibody in response to platelet transfusion

Answer 28

c. Isoagglutinins in platelet's serum coated patient cells Isoagglutininins in platelet's serum coated patient cells. The 25 units of platelets being group O, had both anti-A and anti-A,B, both of which could bind with patient RBCs, causing a positive DAT.

Question 29

Which of the following would most likely be responsible for an incompatible IAT crossmatch? a. Recipient's RBCs possess a low frequency antigen b. Anti-K1 antibody present in the donor unit c. Recipient's RBCs are polyagglutinable d. Donor cells have a positive DAT

Answer 29

d. Donor cells have a positive DAT Donor cells have a positive DAT. The donor cells may have a low frequency antigen, but just the presence of an antigen does not cause a positive AGT test. There is no mention that the patient has the corresponding antibody. Presence of anti-K1 in donor serum is irrelevant, since a major crossmatch uses patient serum and washed donor RBCs. There is no donor plasma in this test. Polyagglutinable cells would only cause a problem at IS if human source ABO reagents were used. A positive DAT on the donor cells, would in fact cause a positive reaction, every time the donor cells were tested via an AGT test.

Question 30

A 65 year old male is admitted to the hospital for osteomyletis. He has been taking oral penicillin for the past two months. His type and screen give the following results: ABO/Rh = O positive Antibody screen: SCI, SCII and Auto 3+ at AHG. A DAT is performed and the results are PS = 2+, IgG = 2+, C3 negative. An elu-kit elution is performed and the panel cells are all 3+. The antibody is most likely: a. anti-penicillin b. broad-spectrum warm auto-antibody c. broad spectrum cold auto-antibody d. antibody to a high frequency antigen

Answer 30

b. broad-spectrum warm auto-antibody Although the patient is on penicillin, he is taking oral medication, which is not implicated in the production of an anti-penicillin antibody. Those antibodies are typically seen in patients taking large amounts of IV penicillin. In addition, the penicillin antibody reacts only in the presence of drug coated cells. This is most likely a warm autoantibody of broad specificity. The screen is positive at AGT with all cells tested. The eluate is positive with all cells tested, and teh DAT is positive due to IgG.

Question 31

Quinidine is most commonly associated with which mechanism of drug induced hemolysis: a. membrane modification b. drug adsorption c. immune complex d. warm auto antibody production

Answer 31

c. immune complex Quinidine is most commonly associated with immune complex mechanism. In immune complex, the drug-antibody complex adheres to the surface of the RBC causing a positive DAT.

Question 32

A patient was crossmatched with 9 units of RBCs, one of which was incompatible. The patient has a negative antibody screen testing. If all of the pretransfusion tests were valid, which of the fol owing explanation is NOT a plausible cause for the incompatibility. a. Patient has an antibody directed against a low frequency antigen b. Incompatible donor has a positive DAT c. Patient has an anti-Bga d. Patient has an antibody directed against a high frequency antigen

Answer 32

d. Patient has an antibody directed against a high frequency antigen An antibody directed against a high frequency antigen would have all or almost all panel cells positive, as well as all or almost all crossmatches incompatible.

Question 33

A patient is tested for type and screen and gives the following results. ABO Anti-A = 0 Anti-B = 0 Rh anti-D (IAT) = 2+ Rh control (IAT) = 2+ Antibody screen (AGT results) SCI =2+ SCII = 2+ AC = 2+ What is the most likely explanation for these results? a. patient has a cold autoantibody b. patient has a warm autoantibody c. patient has multiple allo-antibodies d. patient has an alloantibody directed against a high frequency antigen

Answer 33

b. patient has a warm autoantibody The SCI, SCII and AC are all 2+ and the positive Rh control suggests a positive DAT. Of the choices listed, the warm autoantibody is the best selection. A cold autoantibody would not give positive results at AGT. Multiple alloantibodies would not give a positive autocontrol (unless the person were transfused recently). An antibody to a high frequency antigen, would not typically cause a positive auto control.

Question 34

Monoclonal antibodies are produced by: a. adsorbing out other antibodies b. hybridomas c. T-cells d. cancer cells

Answer 34

b. hybridomas A hybridoma is a cell created by fusing two cell lines. A hybridoma will produce numerous copies of the same antibody, and is used to produce monoclonal antibodies.

Question 35

Which of the following should be on a physician's order for blood components? a. Patient's gender b. Patient's diagnosis c. Requesting physician's name d. Patient's date of birth e. Component(s) requested

Answer 35

e. Component(s) requested

Question 36

Which of the following would be acceptable for patient identification when drawing samples for pre-transfusion testing? a. Patient's name on a medical alert identification bracelet b. Identification by a third party, if the patient is unresponsive c. Patient's name outside of the hospital room d. Patient's name on a whiteboard in his or her room e. Hospital chart at the foot of the patient's bed.

Answer 36

b. Identification by a third party, if the patient is unresponsive

Question 37

Which of the following sample/patient pairs is acceptable for crossmatching a unit of blood blood cells (RBCs)? a. Sample drawn 7 days before anticipated transfusion; pregnancy is unknown. b. Sample drawn 5 days before anticipated transfusion; patient delivered an infant 1 month ago. c. Sample drawn 4 days ago before anticipated transfusion; transfusion history is unknown d. Sample drawn 4 days before anticipated transfusion; patient transfused 2 months ago. e. Sample drawn 2 days before anticipated transfusion; patient received RBCs 5 days ago.

Answer 37

e. Sample drawn 2 days before anticipated transfusion; patient received RBCs 5 days ago. AABB standards requires that samples be drawn within 3 days of transfusion if the patient has been transfused or pregnant within the past 3 months or if the transfusion and/or pregnancy history is unknown. Many institutions, because of difficulties obtaining this information, will use a 3 day rule for all patients. The goal of this requirement is to prevent delayed hemolytic transfusion reacts. Individuals with recent transfusions or pregnancies may be forming blood group antibodies that would not be detectable if samples are drawn too far in advance of teh anticipated transfusion.

Question 38

According to AABB standards for Blood Banks and Transfusion Services (Standards), which of the following tests must be performed on every unit of donated blood intended for allogeneic use? a. Antibodies to Hepatitis A virus (HAV) b. Hepatitits C Virus (HCV) RNA c. Antibodies to Hepatitis B surface antigen (HBs) d. Antibodies to cytomegalovirus (CMV) E. Parvovirus RNA

Answer 38

b. Hepatitits C Virus (HCV) RNA The following tests are performed on all units of blood intended for allogeneic transusion

Question 39

How long must a recipient's blood specimen be retained following transfusion? a. 35 days b. 21 days c. 14 days d. 7 days e. 3 days

Answer 39

d. 7 days

Question 40

A type and crossmatch order is indicated with which of the following surgical procedures? a. Cholecystectomy b. Excision of a facial seborrheic keratosis c. Inguinal hernia repair d. Routine caesarean section e. Splenectomy

Answer 40

e. Splenectomy

Question 41

In which of the following cases is weak-D testing required? a. Pregnant female types as Rh negative b. Blood donor types as Rh negative c. Pregnant female types as Rh positive d. Male surgery patient types as Rh negative e. Female surgery patient types as Rh positive

Answer 41

b. Blood donor types as Rh negative

Question 42

Which of the following samples is acceptable for pre-transfusion testing? a. Sample labeled at the nursing station. Label contains the date, patient's full name, hospital number, and phlebotomist's initials. b. Sample labeled in the hallway outside of the patient's room. Label contains the date, patient's full name, hospital number, and phlebotomist's initials. c. Sample labeled at the patient's bedside. Label contains the ate, patient's full name, and phlebotomist's initials. d. Sample labeled at the patient's bedside. Label contains the patient's full name and hospital number. e. Sample labeled at the patient's bedside. Label contains the date, patient's full name, and hospital number.

Answer 42

e. Sample labeled at the patient's bedside. Label contains the date, patient's full name, and hospital number.

Question 43

Which of the following antibodies is least likely to be a naturally occurring antibody? a. anti-D b. anti-I c. anti-Le^b d. anti-M e. anti-N

Answer 43

a. anti-D

Question 44

Which of the following antibodies is most likely to be a naturally occurring antibody? a. Anti-e b. Anti-Fya c. Anti-Jka d. Anti-K e. Anti-M

Answer 44

e. Anti-M Naturally occuring antibodies are usually IgM, cold reactive, and present in the the serum of individuals who have had no known exposure to red cells expressing the antigen (eg, no previous transfusions or pregnancies). Mnemonic for naturally occurring antibodies: LIPMAN (Lewis, Ii, P , M, ABH, N)

Question 45

The reactivity of which of the following antibodies is usually enhanced by the enzyme treatment of red cells? a. Anti-D b. Anti-Fy^b c. Anti-JMH d. Anti-m e. Anti-S

Answer 45

a. Anti-D Enzymes to not readily destroy s and U antigens of the MNS blood group system. Enzymes have no effect on Kell, Lutheran, and Gerbich 3.

Question 46

Which of the following antigens is resistant to denaturation when red cells undergo enzyme treatment? a. Fy^a b. Jk^a c. M d. N e. S

Answer 46

b. Jk^a

Question 47

Which of the following statements about enhancement media and potentiators is correct? a. Albumin enhances antibody uptake by reducing the net negative charge of the red cell. b. Enzyme treatment enhances antibody uptake by decreasing the net negative charge of the red cell by removing sialic acid residues. c. Low ionic strength saline (LISS) enhances antibody uptake by reducing the zeta potential and allows increased attraction between positively charged antibodies and negatively charged red cells. d. Polybereene (Sigma-Aldrich, St Louis MO) enhances the uptake of antibodies by neutralizing the negative charges of the sialic acid residues on red cells e. Polyethylene glycol (PEG) enhances agglutination by decreasing the negative charge (zeta potential) around red cells.

Answer 47

c. Low ionic strength saline (LISS) enhances antibody uptake by reducing the zeta potential and allows increased attraction between positively charged antibodies and negatively charged red cells.

Question 48

Who first described the antihuman globulin (AHG) test? a. Coombs b Landsteiner c. Levine d. Moreschi e. von Descatello

Answer 48

d. Moreschi

Question 49

What is the specificity of the anticomplement activity in broad-spectrum AHG? a. C1 b. C2 c. C3d d. C4 e. C5

Answer 49

c. C3d

Question 50

Polyspecific or broad-spectrum AHG must contain which of the following? a. anti-IgA b. anti-IgD c. anti-IgE d. anti-IgG e. anti-IgM

Answer 50

d. anti-IgG

Question 51

Which of the following represents an appropriate use of the direct antiglobulin test (DAT)? a. Forward-typing a patient to determine the ABO type b. Reverse-typing a patient to determine the ABO type c. Performing an antibody screen d. Performing a crossmatch e. Looking for bound immunoglobulin in a patient with drug-induced hemolysis.

Answer 51

e. Looking for bound immunoglobulin in a patient with drug-induced hemolysis.

Question 52

Which of the following could cause a false-positive DAT result? a. IgA coating of the red cells b. IgM coating of the red cells c. Incubating the cells after the addition of the antiglobulin reagent d. Saline contaminated with colloidal silica e. Use of an EDTA specimen for testing

Answer 52

d. Saline contaminated with colloidal silica

Question 53

Which of the following statements is/are true? a. Antiglobulin reagents used in a DAT include anti-IgA, anti-Cd3, and polyspecific antiglobulin. b. A positive DAT result should trigger an elution procedure. c. A DAT is performed with reagent red cells, similar to an indirect antiglobulin test. d. If the patient has not been transfused within the last 3 months, a positive DAT result is almost certainly due to an alloantibody. e. All of the above

Answer 53

b. A positive DAT result should trigger an elution procedure.

Question 54

All of the following are examples of indirect antiglobulin tests (IATs) except: a. AHG crossmatch b. Antibody elution c. Antibody identfication panel d. Most antibody titration e. Weak D testing

Answer 54

b. Antibody elution An IAT demonstrates in-vitro reactions between red cells and antibodies. In other words, the antibody and its target antigen are incubated together in the test tube. The two bind, and this is detected through the addition of an AHG reagent. Examples of IATs include the following: Weak D testing Antibody Screens Antibody Identification Compatibility testing Some antigen typings Most antibody titration

Question 55

Which of the following is associated with a false-negative IAT? a. AHG reagent containing anti-species antibodies b. Failure to wash the red cells adequately c. Overcentrifugation d. Saline contaminated with colloidal silica e. Sensitized red cells

Answer 55

b. Failure to wash the red cells adequately

Question 56

Which of the following statements concerning the repeat testing RBC units before transfusion is true? a. The ABO typing must be confirmed from an attached segment. b. The Rh typing of Rh-positive units must be confirmed from an attached segment. c. Confirmatory testing must be performed before the original ABO and Rh labels are affixed to the unit. d. Confirmation of the Rh typing of Rh-negative units is not required. e. Confirmatory testing for weak D is required.

Answer 56

a. The ABO typing must be confirmed from an attached segment.

Question 57

A computer crossmatch is appropriate for which of the following patients? a. Patient has a history of anti-Fy^a. Historic blood type is group A, Rh Positive. Typing of current sample is group A, Rh Positive. Anti-Fy^a is not seen. b. Patient has no known previous blood type or antibody screen results. Current antibody screen is negative. Patient types as group O, Rh negative. c. Patient has a history of a negative antibody screen. Historic blood type is group AB, Rh positive. Current antibody screen positive for anti-c. Current blood type is group, AB, Rh positive. d. Patient has no known previous blood type or antibody screen results. Current antibody screen is negative. Patient types as group B, Rh negative. Repeat typing on the same sample is group B, Rh negative. e. Patient has a history of a negative antibody screen. There is no known history of a previous ABO or Rh type. Current antibody screen is negative. Patient types as group A, Rh positive.

Answer 57

d. Patient has no known previous blood type or antibody screen results. Current antibody screen is negative. Patient types as group B, Rh negative. Repeat typing on the same sample is group B, Rh negative.

Question 58

Which of the following blood components does not need to be crossmatched with a patient's serum sample? a. Apheresis platelet product containing 3 mL of red cells. b. Granulocyte product collected by apheresis. c. Granulocyte product collected by centrifugation of a whole blood donation. d. Leukocyte-reduced RBCs. e. Pooled platelet product containing 1.5 mL of red cells.

Answer 58

e. Pooled platelet product containing 1.5 mL of red cells.' AABB Standards requires that components containing more than 2 mL of red cells must be crossmatched. Granulocyte products typically have a significant red cell content and therefore must be crossmatched. Components with less than 2 mL of red cells (FFP, Cryo, most apheresis platelet products, and most whole blood derived platelet pools) do not need to be crossmatched.

Question 59

Which of the following crossmatch techniques would most likely detect the combination of anti-Wr^a in the recipient and the Wr^a antigen on red cells from a donor. a. complete crossmatch b. computer crossmatch c. immediate-spin crossmatch d. minor crossmatch e. platelet crossmatch

Answer 59

a. complete crossmatch

Question 60

A patient with an antibody to high-incidence antigen has an emergency need for blood. The only available antigen negative compatible units are ones for which testing for transfusion transmitted diseases has not been completed. Which of the following statements is true? a. The units should not be labeled to indicate the pending tests because it might alarm the patient. b. The pending testing need not be completed if the units are transfused because harm has already been done if the units are infected. c. Additional testing would not be necessary if these were apheresis units of the same component from the same donor transfused to the same recipient within 30 days of the original unit that was fully tested. d. It is not required that the physician requesting the transfusion be notified of reactive test results because the units have already been transfused. e. A statement signed by the ordering physician is not needed to document emergency release because it will increase legal liability.

Answer 60

c. Additional testing would not be necessary if these were apheresis units of the same component from the same donor transfused to the same recipient within 30 days of the original unit that was fully tested. AABB Standards require that units of blood released before the completion of testing designed to prevent disease transmission must: Be conspicuously labeled with the testing that is not complete. Have the testing completed as soon as possible. Be accompanied by a statement signed by the requesting physician indicating that the clinical situation was urgent enough to require release before the completion of testing. In the event that a unit must be released before the completion of all required infectious disease testing, if a test proves to be reactive, the transfusion service and the ordering physician must be notified as soon as possible. For a cytapheresis donor dedicated to support a specific patient, testing must be performed before the first apheresis component is released for transfusion and at least every 30 days thereafter.

Question 61

Which of the following statements concerning the testing of autologous blood is true? a. If the unit is to be shipped outside the collecting facility, anti-hepatitis B core (HBc) b. If the unit is to be used within the collecting facility, anti-HIV 1/2 testing need not be performed. c. If the unit is to be shipped outside the collecting facility, anti-HIV 1/2 testing need not be performed. d. If the unit is to be shipped outside the collecting facility, anti-hepatitis B surface antigen (HBsAg) testing must be performed. e. If the unit is to be used within the collecting facility, anti-HBs testing must be performed.

Answer 61

b. If the unit is to be used within the collecting facility, anti-HIV 1/2 testing need not be performed. AABB Standards notes that all required infectious disease tests, including anti-HIV 1/2, be performed if the unit will be transfused outside the collecting institution. If the unit is to be transfused within the collecting facility, these required tests need not be performed. The patient's physician must be notified of any abnormal results obtained when autologous units are tested. If a unit is to be shipped to another facility has abnormal infectious disease test results, the receiving facility must be notified by the shipping facility.

Question 62

A variation of reaction strength is observed with 8 out of 10 panel cells tested in the AHG phase of antibody identification. The autocontrol is negative. These findings are most likely associated with which of the following. a. anti-Co^a b. anti-E c. anti-k d. multiple alloantibodies e. warm-reactive autoantibodies

Answer 62

d. multiple alloantibodies A variation of reaction strength may be observed in the AHG phase of testing, when multiple blood group alloantibodies are present. Variations can also be seen with P1 antibodies (because of the variable strength of P1, antigen expression on red cells) and antibodies exhibiting a dosage effect. If anti-Co^a is present, 1 out of 10 panel cells (not out of 10) should show reactivity at the AHG phase of testing during antibody identification. Colton System Antigens Co^a Frequency: 10.7% Co^b Frequency: 99.9%

Question 63

Which of the following antigen is associated with polyagglutinability? a. C antigen b. K antigen c. Kx antigen d. T antigen c. V antigen

Answer 63

d. T antigen

Question 64

Which of the following lectin-antigen pairs is correct? a. Vicia graminea and the B antigen b. Bandeiraea simplicifolia and the N antigen c. Dolichos Biflourus and the Cad antigen d. Salvia horminum and the T antigen e. Arachis hypogaea adn the A1 antigen

Answer 64

d. Salvia horminum and the T antigen Lectins are proteins extracted from plants that bind to specific carbohydrate antigens. They are sometimes used as an alternative to reagent antibodies. The specificity of the lectin can depend on the dilution of the lectin.

Question 65

Patients less than 4 months of age have somewhat different pre-transfusion testing requirements than older children, and adults. Which of the following statements regarding pre-transfusion testing gin patients less than 4 months of age is true? a. An initial pre-transfusion sample is not required as long as mother is group O and the infant will only receive group O red cells. b. It is critical to only use serum or plasma from mother to detect unexpected antibodies affecting the infant. c. An infant's serum or plasma must always be tested for ABO antibodies. d. If antibody of maternal origin is detected, it is essential to crossmatch appropriate units of blood prior to transfusion of the infant. e. If no clinically significant antibodies are detected, crossmatching is not required and repeat testing may be omitted during any single hospital admission.

Answer 65

e. If no clinically significant antibodies are detected, crossmatching is not required and repeat testing may be omitted during any single hospital admission. Patients less than 4 months of age generally ave abridged pre-transfusion testing requirements. The main reasons are: 1. all unexpected antibodies detected are assumed to have arisen in the mother. 2. Excessive blood draws are the primary contributor to anemia in this age group. An initial pre-transfusion sample is always required. Serum or plasma from either the mother or the infant may be used to detect unexpected red cell antibodies and for cross-matching.

Question 66

In urgent transfusion situations, the usual pre-transfusion testing procedures may be abridged. Which of the following statements is true? a. A signed statement from the clinician, acknowledging that the clinical situation is sufficiently urgent to require release of uncrossmatched or partially crossmatched blood, must be present in the blood bank before units can be release. b. If the patient's ABO group and Rh type are unknown, group O-negative red cells must always be provided. c. If uncrossmatched blood must be released, it should never be matched for ABO (it should always be group O) d. It is important to note on the unit tag or label that compatibility testing was not complete at the time of issue. e. If uncrossmatched units of blood are released, it is not essential to complete routine compatibility testing.

Answer 66

d. It is important to note on the unit tag or label that compatibility testing was not complete at the time of issue.

Question 67

Which of the following statements regarding rare units of blood is true? a. Most allogeneic donors will be compatible. b. Rare units are most frequently required in the setting of warm-reactive auto-antibodies. c. Most donor centers will have access to rare donor units in their inventories. d. Family members represent a potential source of rare blood donors. e. Units that are negative for high-prevalence antigens are the only rare units for which it is appropriate to contact a rare-donor inventory

Answer 67

d. Family members represent a potential source of rare blood donors.

Question 68

Many drugs have been implicated as a cause of immune-mediated hemolysis. Which of the following drug-related mechanisms for a reactive DAT result is least likely to be associated with overt hemolysis? a. Antibody formation against a drug, with absorption of the immune complex to the red cell membrane. b. Antibody formation against a red cell membrane component in association with the drug. c. Antibody formation against the drug and a red cell membrane component. d. Auto-antibody formation in association with a drug. e. Non-imunologic protein adsorption onto the red cell membrane caused by the drug.

Answer 68

e. Non-imunologic protein adsorption onto the red cell membrane caused by the drug.

Question 69

Which of the following is not true of monoclonal reagents? a. Monoclonal reagents are produces for single antigens with more than one epitope. b. Monoclonal reagents are highly specific. c. Monoclonal reagents are highly characterized and are uniformly reactive. d. Monoclonal reagents are produced by hybridoma technology.

Answer 69

a. Monoclonal reagents are produces for single antigens with more than one epitope. The question is asking which is NOT true. Monoclonal reagents are prepared to be specific to a single epitope of an anigen-not multiple epitopes. Reasons that we produce monoclonal antibodies are that they are highly specific and uniformly reactive. Monoclonals are produced via hybridoma technology.

Question 70

When a new assay is implemented, what measure is taken to determine equivalency? a. Lot to lot testing of new and old lot numbers of reagent. b. Work-flow reorientation c. Daily quality control d. Calibration

Answer 70

a. Lot to lot testing of new and old lot numbers of reagent. This question is a good example of an SBB question about lab operations, and requires you to think about the concept of equivalency. Equivalency means that two similar things are shown to be nearly equal. Of the concepts listed here as choices, only "lot to lot testing" shows a level of equality. Work-flow reorientation may be necessary when implementing new equipment, but this is not going to show equivalency between old and new techniques. Quality control and calibration are designed to show that a process is in compliance at a certain point in time. Depending on what you are implementing, the calibration and QC values may or may not correspond. Only lot to lot testing of old and new reagents will show equivalency. Reagents should perform in a similar fashion regardless of the equipment used.

Question 71

An AB positive mother has an infant with anemia and a positive DAT. The mother's antibody screen is negative. You advise: a. To screen the mother's serum for antibody against a high-incidence antigen. b. To screen the mother's serum against the father's red cells. c. To perform an antibody panel on the infant's serum. d. To screen the mother's serum for antibody against a low-incidence antigen.

Answer 71

b. To screen the mother's serum against the father's red cells. You want to perform the procedure that will tell you the most information the quickest. If you screen against a "low incidence" antigen cell, then which low incidence antigen will you select? Also we want to know right away if the infant's anemia and DAT are caused by an alloantibody or some other process. Testing against the father's cells will tell us right away if this is HDFN or another hemolytic process.

Question 72

A 65 year old man with chronic lymphocytic leukemia (CLL) presents with a history of fatigue, jaundice, and dark colored urine. Three weeks ago, he received a transfusion of 2 RBC units at an outside hospital for anemia. His hemoglobin is 7 g/dL. His DAT is 3+ with polyspecific reagent, 3+ with anti-IgG, and negative with anti-C3d. His antibody identification panel shows 3+ reactivity with all cells including the autocontrol. Which of the following tests is indicated in order to help identify compatible RBC units for transfusion? a. Absorb the patient's serum with rabbit erythrocyte stroma. b. Prewarm the patient's sample and reagents when doing the testing. c. Absorb the patient's serum with his own enzyme-treated cells. d. Absorb the patient's serum with three enzyme treated red cells of complementary phenotype.

Answer 72

d. Absorb the patient's serum with three enzyme treated red cells of complementary phenotype. This patient has been recently transfused, so we cannot autoabsorb his serum. We are not focusing here on a cold autoantibody, so performing a prewarm, or using rabbit stroma will not be helpful. The recent transfusions and hemolytic process suggest alloantibodies, so performing adsorptions with three aliquots of cells help to remove the autoantibody and identify alloantibodies.

Question 73

A 65 year old male patient presents to the emergency department with new-onset jaundice. He is easily fatigued and breathless on exertion. His pulse rate is 120 bpm, and his hematocrit is 16%. The patient states that he has never been transfused. Blood bank evaluation indicates that the patient has a serum antibody that reacts with all reagent red cells and that his DAT is positive. Two RBC units are ordered for urgent transfusion. You recommend: a. Infusion of a crystalloid or colloid because a crosspatch-compatible unit will not be available. b. The transfusion of 2 units of crosspatch-incompatible blood. c. Withholding transfusion unless absolutely necessary d. The that blood bank continue to crossmatch units until compatible units are identified.

Answer 73

b. The transfusion of 2 units of crosspatch-incompatible blood. This patient is in critical condition: tachycardia, breathless, jaundiced, low Hgb. He needs a transfusion right away, so we will have to give incompatible blood. While the RBC may have shortened survival, he may still get enough of a bump in hemoglobin to relieve his distress.

Question 74

Graft-vs-host disease following hematopoietic progenitor cell (HPC) transplant occurs as a result of: a. ABO incompatibility between the donor and recipient. b. Advanced patient age c. Differences between donor and recipient sex. d. HLA compatibility between the donor and recipient.

Answer 74

d. HLA compatibility between the donor and recipient.

Question 75

In the autoabsorption procedure for the removal of cold autoagglutinins from serum, pre-treatment of the patient's RBCs with which of the following regents is helpful. a. Ficin b. Phosphate buffered saline c. LISS d. Chloroquine diphosphate

Answer 75

a. Ficin For COLD auto-antibodies, ficin is the reagent of choice for treating the patient cells. Chloroquine diphosphate will remove the antibody, but the treated cells will not absorb the cold auto as well when they are ficin treated. Per AABB Method 4-5 COLD AUTOADSORPTION PROCEDURE Although most cold auto-antibodies do not cause a problem in serologic tests, some potent cold-reactive auto-antibodies may mask the concomitant presence of clinicallys significant alloantibodies. In these cases, adsorbing the serum in the cold with autologous red cells can remove the autoantibody, permitting detection of underlying alloantibodies. In the case of most nonpathologic cold auto-antibodies a simple quick adsorption of the patient's serum with enzyme-treated autologous red cells will remove most cold antibody.

Question 76

Which of the following serologic evaluations is most important in the assessment of a possible acute hemolytic transfusion reaction? a. Antibody screen b. Antibody Identification panel c. Direct antiglobulin test d. Rh type

Answer 76

c. Direct antiglobulin test In an acute HTR, performing the DAT will let us know if the hemolysis is due to an antibody.

Question 77

A type and screen is done on a 49 year old woman who is scheduled for a hysterectomy in 1 week. Her blood type is A positive, and her antibody screen was positive. What must be done before her surgery date? a. Identify antibody. b. Identify antibody and phenotype RBC units. c. Phenotype the patient. d. Identify antibody and phenotype platelets.

Answer 77

a. Identify antibody. We can not say for sure that we have to antigen type the RBCs. The question states that the antibody screen is positive,but does not indicate that the antibody is clinically significant. Because there is no information on the clinical significance of the antibody, we do not know for sure if antigen typing is necessary.

Question 78

A patient has a positive antibody screen and a positive antibody identification panel. All tested cells are positive 3+ at the AHG phase of reactivity. The autocontrol is also positive 3+ at the AHG phase. The patient has no recent transfusions or pregnancies. Which technique is the next BEST one to perform for this case? a. Elution b. Cell separation c. Warm alloadsorption d. Warm autoadsorption

Answer 78

Correct: Warm Autoadsorption Since the patient has never been exposed to allogeneic red blood cells, the test results suggest the patient has an autoantibody. You can use an adsor Links to an external site.ption Links to an external site. technique to confirm this panagglutination testing reactivity. The antibody reacts at the AHG phase of testing. This indicates a warm autoantibody and the autoadsorption should take place at 37C. Since the patient has not been transfused or pregnant in the last 3 months, you can use the autologous patient cells to conduct the adsorption. The autoadsorption will act to "soak up" the autoantibody and leave behind serum that can then be used to screen for additional antibodies (the "left-behind" serum is known as "adsorbed serum"). While performing an elution is important to this case, it is not the BEST step to perform next. Odds are, the pannaglutinin we see in the serum will react with all cells tested in the eluate. This does not reveal any new information, nor does it get us closer to a solution and ability to safely transfuse this patient. Cell separation technique, and allo-adsorption are not necessary as the patient has no recent exposure to foreign RBCs via pregnancy or transfusion. Sometimes, this question appears with a choice of performing a chemical modification to the cells or serum, such as AET or ficin treatment of RBCs or using sulfhydryl reagents with the plasma to distinguish IgG from IgM antibodies. While these techniques are helpful in some cases, they are still not the best choice here. If we suspect a warm autoantibody, additional testing is aimed at identifying underlying alloantibodies. A warm autoantibody will likely cause shortened RBC survival, but underlying alloantibodies can result in hemolytic transfusion reactions, so we need to provide antigen negative RBCs if required. I would not choose to use reagents to distinguish between IgM and IgG antibodies, such as treating the serum with sulfhydryl reagents such as 2ME or AET. Since the antibody is reacting only at the AHG phase, it is most likely IgG. Using reagents to treat the RBCs, may or may not reveal information that is helpful. If I run a ficin panel, that can help to identify antibodies directed at antigens that are enzyme sensitive, but what are the odds that this is such an antibody? AET can help with Kell system antibodies, but again, there is too little information to jump to that. If the AET panel is still entirely positive, then we have nothing new. Again, our focus is not to identify the specificity of the autoantibody, but look for underlying alloantibodies, which would be found if we removed the autoantibody through warm autoadsorption.

Question 79

A patient has a positive antibody screen and a positive antibody panel. All panel cells are positive 3+ at the AHG phase of reactivity. The only tested cell that is negative is the autocontrol. You phenotype the patient and find negative results for the following antigens: E, Fya, S, and Jkb . You locate a testing cell which is phenosimilar. The cell reacts 3+ at the AHG phase. Of the following choices, which is the most likely specificity of the antibody/antibodies? a. Allo-anti-k b. Allo-anti-e, -Jk(a), -Fy(b) c. Allo-anti-E, -Fy(a), -S, -Jk(b) d. Warm Autoantibody

Answer 79

Correct: Allo-anti-k Since the autocontrol test was negative, there are no autoantibodies in the patient. The testing reveals that a cell that is phenotypically matched with the patient is incompatible with the patient's serum. This suggests that the patient has an antibody against a high incidence antigen (one present on just about everyone's red cells). If the patient had multiple antibodies against the common antigens they were negative for(choice C), this cell would have been compatible with patient specimen. The patient is positive for the antigens listed in choice B and should not make alloantibodies to these antigens. The k ("little k" - cellano) antigen is present in 99.9% of the population, and an antibody against it is the best of these choices. Of course in the real clinical laboratory, we would not assume it is only one antibody. It could be multiple antibodies that have specificities other than the ones listed. The reagent cells are all the same strength, and the auto control is negative, which suggest one antibody to a high prevalence antigen. So for this question, the best answer is allo-anti-k.

Question 80

A patient with sickle cell disease was transfused 2 units of red blood cells 2 weeks ago. A patient pretransfusion phenotype was not obtained prior to this transfusion. What technique can be used to obtain the patient phenotype in this case? a. Wash the patient's red cells with hypotonic saline (0.3%) b. Wash the patient's red cells with hypertonic saline (1.2%) c. Treat the patient's red cells with the ficin enzyme d. Perform a cold-autoadsorption on the patient specimen e. Perform a reticulocyte separation by micohematocrit separation

Answer 80

Correct: Wash the patient's red cells with hypotonic saline (0.3%) RBCs with Hemoglobin S (HbS) react differently than RBCs with HbA when exposed to hypotonic (0.3%) saline. The transfused RBCs, which contain HbA, will be hemolyzed by the hypotonic (0.3%) saline. The patient's own RBCs (with HbS) will not be hemolyzed. This allows us, in most cases, to phenotype the remaining autologous RBCs after about 6 hypotonic (0.3%) saline washes. Ficin would not be expected to separate the patient's from the transfused red cells. Cold autoadsorption is not indicated for separating red cells. Reticulocyte separation by microhematocrit separation- Red cells from patients with hemoglobin S or spherocytic disorders are not effectively separated by this method (see AABB Method 2-23 for an alternative procedure). AABB.org\methods

Question 81

An antibody screen and autocontrol are tested and gives negative results with screening cells I, II and III. When the testing is complete, the technologist notices that the dry heating block incubator temperature is at 25oC, rather than at the required 37oC. Which stage of the agglutination reaction would be most affected by this error? a. Sensitization b. Lattice formation

Answer 81

Correct: Sensitization Agglutination reactions occur in two stages. First, antibodies attach to the corresponding antigens on the RBC membrane which is called sensitization. The second stage, lattice formation (also called bridge formation) involves linking between sensitized RBCs to form visible agglutination. Sensitization is affected by changes to the environment in which the antibody-antigen binding occurs. Factors like temperature, pH, incubation time, ionic strength of the solution can affect the ability of the antibody to bind to the antigen if the conditions are less than optimal. Sensitization can also be affected by the quality and quantity of antigen sites and antibody molecules as well as the accessibility of antigens on the RBC membrane. If there are less antigen sites, or less molecules of antibody, then of course we will have less opportunities for the antibody to coat the RBC surface. If the RBC antigens are not positioned to be accessible on the RBC membrane, the antibody, though present, may not be able to physically connect to the antigen. Other factors include the ratio of antigen/antibody as well as the "goodness" of the fit between antigen/antibody as well as the avidity of the antibody for the antigen. Lattice Formation occurs when the sensitized RBCs form cross-links to result in visible agglutination. Factors that influence this step include number and size of antigen sites, size and number of Ig molecules (i.e. IgG require more molecules to crosslink). Centrifugation is a huge factor here, because too light or too heavy centrifugation can impact the ability of the RBCs to link and be resuspended as visual agglutinins. Zeta Potential is a big factor in this stage. Zeta potential is the net negatively charged ions that surround the RBCs, and cause a natural repulsion between cells. So sensitized cells must overcome zeta potential in order to crosslink.

Question 82

An enzyme-linked immunosorbent assay (ELISA) is selected for hepatitis B surface antigen testing at your facility. A group of students are visiting your facility and one asks "In any ELISA method, I know that there is a second antibody added which is linked to a reporter enzyme, but what is this called?" You respond: a. target antibody b. conjugate c. capture antibody d. surrogate

Answer 82

Correct: conjugate Conjugate in any ELISA context refers to the process of chemically linking an antibody to a specific tag. Due to their specificity, antibodies are widely used to detect and quantify antigens in numerous applications such as flow cytometry, ELISA, western blotting, immunohistochemistry, and lateral flow. There are form main types of ELISA including direct, indirect, sandwich and competitive. For the SBB understand the value of the conjugate antibodies. target antibody= targets the protein of interest conjugate= tagged antibody capture antibody= antibody immobilized on the surface of the wells of the plate surrogate= surrogate as an immune marker that can substitute for the clinical end point https://en.joysbio.com/what-is-a-lateral-flow-assay-and-how-does-it-work/

Question 83

As part of an antibody ID investigation, the technologist suspects the patient has an anti-k (little k), anti-Jka, anti-Fya, anti-S and anti-C. She decides to perform an adsorption to remove the anti-k. Which phenotype cell below is the best choice as an adsorbing cell? a. AET/DTT treated cell with phenotype: k+, Jka-, Fya-, S-, C- b. Ficin treated donor cell with phenotype: k+, Jka-, Fya-, S-, C- c. ZZAPP treated donor cell with phenotype: k+, Jka+, Fya+, S+, C+ d. Untreated donor RBC with phenotype: k-, Jka+, Fya+, S+, C+

Answer 83

Correct: Ficin treated cell with phenotype: k+, Jka-, Fya-, S-, C- When we wish to adsorb out an antibody, we choose a cell that is POSITIVE for the corresponding antigen, and negative for all antigens corresponding to the other antibodies present. So in this case we choose a cell that is only positive for k, and negative for Jka, Fya, S, C. So that rules out any cell that is positive for antigens other than k. Next, we need to think about whether or not we should treat the adsorbing cells with a chemical to enhance antibody uptake. So we look for chemicals that will help to make antigen sites more accessible. In the case of Kell, the antigens are destroyed by AET (note AET and DTT are equivalent) treatment, so although the phenotype matches, the k+ antigen will be destroyed by AET. Ficin really does not enhance the reactivity or antibody uptake for Kell system antibodies, but in this scenario, it is the only viable option. SBB exam: Know which antigens are affected by which chemicals/enzymes. We will go into more detail on chemical/enzymes during the Blood Groups review.

Question 84

When performing an elution, what is the purpose of testing the last wash? a. To determine that antibody coated cells were prepared properly b. To check the pH of the eluting fluid c. To assure that all unbound antibodies were removed by washing d. To verify that bound antibodies remain on the patient cells.

Answer 84

Correct : To assure that all unbound antibodies were removed by washing In an elution procedure, we first wash the sensitized RBCs to remove any unbound antibodies that may interfere with the eluate. We test the last wash against (usually) screening cells to make sure that there are no remaining unbound antibodies. One of the choices, " To determine that antibody coated cells were prepared properly " is not fully correct. That answer is too vague when compared to the one above, which describes a more exact reason for testing the last wash.

Question 85

A cell separation is performed in a patient who is recently transfused as part of antibody ID testing. The microhematocrit tubes are spun and the top layer of cells harvested. Theoretically, which cells will be in the top layer of the microhematorcit tube? a. Older Donor Cells b. Older Patient Cells c. Donor Reticulocytes d. Patient Reticulocytes

Answer 85

Correct: Patient Reticulocytes In cell separation, the goal is to harvest only patient cells. Reticulocytes are less dense than older cells, so they will rise to the top of the hematocrit tubes when they are centrifuged. In a normal individual, the mature RBC has a lifespan in the peripheral circulation of 120 days, as opposed to the reticulocyte which will only appear in the peripheral circulation for about 1 day. In a donated unit of blood, any reticulocytes would have broken down before transfusion. Additionally, a patient who requires transfusion is likely to be anemic, and therefore likely to have a higher than normal reticulocyte count.

Question 86

An antibody ID investigation is being performed on a sample from a 40 year old female who received 4 units of RBCs one year ago. The antibody ID panel is 2+ with all cells tested, and the autocontrol is positive 2+. The DAT is 2+ with polyspecific and anti-IgG reagents. A technologist opts to treat the patient cells with chloroquine disphosphate as part of the antibody ID procedure. Which choice below represents what she is most likely trying to accomplish? a. Remove and concentrate bound antibody from the RBCs b. Phenotype the patient RBCs c. Separate patient RBCs from transfused RBCs d. Prepare the patient RBCs for autoadsorbing.

Answer 86

Correct: Phenotype the patient RBCs Choloroquine disphosphate breaks the bonds between bound antibody and the RBC membrane antigens to remove antibody off sensitized RBCs without damaging the cells. The antibodies get destroyed and you are able to antigen type the RBCs. This procedure may be performed on patients who have not been recently transfused. If someone was transfused recently, you would have to go on to perform cell separation to harvest only patient cells after treatment. Since this patient was not recently transfused, we can rule out that option. While you could use choloroquine to prepare cells for autoadsorbing, we would more likely use ZZAP which is cheaper, faster, and less complicated to perform. Again, the SBB exam is asking you to pick the BEST answer, not just a correct one.

Question 87

A patient with Multiple Myeloma is unable to be tested for ABO due to rouleaux reactions. Which technique below will be the best choice to resolve the testing problems due to rouleaux? a. Pre-warm technique b. Saline replacement c. Use of high protein reagents d. Perform the testing at 4oC

Answer 87

Correct: Saline replacement Rouleaux occurs because of serum abnormalities, and can be seen in patients with Multiple Myeloma. Saline replacement removes the extra proteins from the test systems and allows the cell button to be resuspended without the presence of the large proteins. Therefore the red cells won't artificially adhere to each other. Rouleaux could initially be confused for a cold agglutinin. A pre-warm technique will not disperse the reactivity. High protein reagents would exacerbate the problem since the rouleaux is due to an already high protein environment. Performing the testing at 4oC would not resolve the issue.

Question 88

A serologic phenotype was performed on a patient and it was determined the patient lacked the antigen. However, when the patient's DNA was analyzed by a DNA array, it indicated the patient had the genetic change associated with the antigen. Which of the following are possible causes of this discrepancy? **Select ALL possible correct answers. -Variation in DNA regions not tested by the array - Insufficient DNA sample tested - Weak antigen expression - Positive direct antiglobulin test (DAT)

Answer 88

Correct: Variation in DNA regions not tested by the array AND weak antigen expression In general, DNA arrays only evaluate known common polymorphisms and do not analyze the entire DNA sequence. These methods are well suited to detect new variations in the DNA sequence or to detect the present of novel changes in inhibitor or precursor genes that could impact the ability of the antigen to be present phenotypically. However, weak, modified and partial phenotypes can cause false negative serologic testing results. This is especially true of weak Fyb for Caucasians and weak/partial Rh antigens for those of African ancestry. AABB Technical Manual 20th ed. Chapter 8 Reliability of labeling red cell units with minor antigen historical results and process considerations - DePalma - 2020 - Transfusion - Wiley Online Library

Question 89

Select the complimentary base pair in RNA to adenine? a. Thymine b. Uracil c. Cytosine d. Guanine

Answer 89

Correct: Uracil In DNA, the four nucleotides are adenine, guanine, cytosine, and thymine. Complementary pairs are adenine and thymine, guanine and cytosine. In RNA, the four nucleotides are adenine, guanine, cytosine, and uracil. Adenines complementary nucleotide is uracil.

Question 90

Homozygosity for a mutation in GATA-1 upstream from the Duffy gene is commonly found in African Americans. This inherited mutation results in what kind of effect on patient cells? a. No Duffy antigens expressed on any of patient’s cells b. Both Duffy antigens expressed on patient cells c. No effect on the expression of Duffy antigens d. No Duffy antigens expressed only on patient’s red cells

Answer 90

Correct: No Duffy antigens expressed only on patient’s red cells This mutation disrupts binding of the erythroid-specific GATA-1 transcription factor and prevents expression of the gene in red cells, but not in other cells, e.g. tissue endothelium. Individuals that are Fy(a-b-) due to this SNP also lack DARC on their red cells and are resistant to malaria.

Question 91

The postzone effect is due to excess ____________. a. Antigens b. Protein c. Antibodies d. Agglutination

Answer 91

Postzone effect is due to excess antigens and will cause a false-negative reaction, just like in the prozone effect. Each antibody binds to different epitopes on the red cells and prevents crosslinking and agglutination.

Question 92

A group O person is transfused with group A red cells. Which type of hemolysis will occur? a. Delayed b. Extravascular c. Intravascular d. Hyperhemolysis

Answer 92

Correct: Intravascular In cases of ABO incompatible transfusions, the MAC quickly assembles and lyses red cells before C3b/IgG opsonization can occur and induce phagocytosis. When the red cells lyse in circulation, it is called intravascular hemolysis. Clinical signs and symptoms will be acute due to the high toxicity of free hemoglobin in circulation.

Question 93

A pregnant woman is found to have hemolytic anti-Lea in her serum. The husband types Le(a+). This is her third child. What is the chance that the fetus will develop HDFN? 0% 50% 75% 100%

Answer 93

Correct: 0% Lewis antigens are not well developed on cord cells and most newborns type Le(a-b-). As children grow, they may transiently type Le(a+b+) but reliable Lewis phenotyping is not developed until age 5 or 6. T Lewis antibodies are predominantly IgM and not a cause of HDFN. Even if the anti-Lea is hemolytic and has an IgG portion, the antibody will not bind to the fetus/newborn's red cells. SBB Exam: This is a common question that presents with the Lewis antigens and the above explanation is what they're looking for. In the 20th Edition of the AABB Manual (Page 315), it mentions that approximately 50% of newborns will type Le(a+) after enzyme treatment. This means the antigens may be extremely weak but does not change the history of Lewis antibodies not causing HDFN.

Question 94

The prozone effect is due to excess ___________. a. Antibodies b. Antigens c. Protein d. Agglutination

Answer 94

Correct: Antibodies A prozone may occur with an unusually high antibody concentration that diminishes the chance of antibody binding two separate particles or red cells. No visible agglutination can occur. In serology, this effect is unusual but may occur if the red cell antibody is very high and may cause discrepant reverse typing. Diluting the serum will resolve the prozone issue.

Question 95

A positive agglutination using tube method would appear as: a. Visual adhesion of red cells to one another in a pellet post centrifugation b. Spread pattern of red cells in individualized wells c. Agglutinated red cells retained in a dextran-acrylamide matrix d. Button of red cells at the base of an individual well

Answer 95

Correct: Visual adhesion of red cells to one another in a pellet post centrifugation Spread pattern of red cells in individualized wells = Microtiter Agglutinated red cells retained in a dextran-acrylamide matrix = Gel-based Button of red cells at the base of an individual well = Negative Reaction in Solid Phase All are fluid-phase assays based on agglutination except the button of red cells is a negative reaction for solid phase when no protein adsorbs from the solution to the protein bound to the plastic. When nothing has bound, the red cells cluster together as a “button” in the bottom of the well. A positive reaction would show dispersion of the red cells over the surface of the well.

Question 96

IgG antibodies causing red cell destruction by inducing extravascular hemolysis do so by: (Select all that apply) a. Phagocyte consumption through Fc receptors b. None, IgG antibodies cause intravascular hemolysis c. Phagocyte consumption through complement-based opsonization d. Complement activation and insertion of the membrane attack complex

Answer 96

Correct Answers: Phagocyte consumption through Fc receptors and Phagocyte consumption through complement-based opsonization Extravascular hemolysis usually presents as delayed hemolytic transfusion reactions. IgG antibodies can induce phagocytosis via Fc receptors and/or opsonization. In this method, red cells are destroyed OUTSIDE of their normal compartment (Extra as a prefix means outside or beyond). The red cells are destroyed by phagocytes using the RES system. Remember, the RES system evolved to break down and recycle autologous red cells as part of cell turnover; however, the destruction of incompatible red cells overwhelms the system and can cause substantial morbidity (and occasionally mortality).

Question 97

The development of protein from RNA is referred to as: a. Transcription b. Translation c. Activation d. Recombination

Answer 97

Correct: Translation DNA has to be transcribed to RNA to be translated to protein.

Question 98

If a patient’s serum was adsorbed with allogeneic R1R1 cells that are Jk(a-b+), which alloantibodies would remain behind, if present? a. Anti-C, -e, -Jka b. Anti-c, -E, -Jkb c. Anti-D, -C, -e, -Jkb d. Anti-c, -E, -Jka

Answer 98

Correct: Anti-c, -E, -Jka R1R1 Jk(b+) cells = Rh+, C+, e+, Jkb+ Using R1R1 Jk(b+) red cells to adsorb serum will result in anti-D, -C, -e, and -Jkb being removed from the serum onto the red cells, if present. The red cells cannot remove antibodies to antigens that are not present and therefore would leave behind anti-E, -c, and -Jka.

Question 99

Pretransfusion compatibility testing must include: a. Antibody Screening b. Autocontrol c. Weak D test on the recipient d. DAT

Answer 99

Correct: Antibody screening We are NOT required to perform DAT or an autocontrol as part of routine pretransfusion testing. These two tests are performed to determine if there is in-vivo sensitization of the patient's RBCs or if the patient has an autoantibody. These tests might be included as part of an extended antibody ID workup but are not included in routine pre-transfusion testing. The weak D phase is also not required for patients. If the patient anti-D result is negative at immediate spin then the patient can be called Rh-negative without additional testing. If this was a DONOR, we would need to test for weak D as the D antigen is highly immunogenic and even a weaker expression of D antigen in donor cells can possibly stimulate a patient to produce allo-anti-D