HTLA and other blood group systems Flashcards
(14 cards)
Which of the following is true regarding the Yt blood group system?
a. Antigens are destroyed by all common enzymes
b. Not denatured by DTT
c. Antibodies are usually IgM
d. Antibodies are usually IgG
d. Antibodies are usually IgG
Which of the following is true regarding the Xg blood group system?
a. Antibodies are enhanced using enzymes
b. Antibodies are IgM
c. Antibodies react in the AHG phase
d. Xga is clinically significant
c. Antibodies react in the AHG phase
John Milton Hagen (JMH) antigens are destroyed by proteolytic enzymes:
a. True
b. False
a. True
Cromer antibodies are usually:
a. IgM
b. IgG
c. Not neutralized by Cromer positive serum
d. Implicated in HDFN
b. IgG
Which of the following is false regarding the Knops blood group system?
a. Antigens are resistant to ficin
b. Antibodies are not clinically significant
c. Antigens are located on a complement glycoprotein
d. Antigens are destroyed by ficin
d. Antigens are destroyed by ficin
Which of the following is true regarding the Colton system?
a. Antibodies are usually IgG
b. Not implicated in HTR
c. Antibodies are usually IgM
d. Not implicated in HDFN
a. Antibodies are usually IgG
What is unique about the Chido/Rogers system?
a. Antibodies are neutralized by antigen negative plasma
b. Antibodies are neutralized by antigen positive plasma
c. Antigen negative blood is required for transfusion patients with antibodies
d. Antibodies are implicated in HDFN
b. Antibodies are neutralized by antigen positive plasma
How is anti-SC3 produced in patients?
a. Produced in patients with SC1
b. Produced in patients with SC3
c. Produced in patients with Scianna null phenotype
d. Produced in patients with SC2
c. Produced in patients with Scianna null phenotype
Ina and Inb are destroyed by:
a. Papain
b. Ficin
c. DTT
d. all of the above
d. all of the above
What antibody is suspected when all 12 panel cells are reactive at AHG phase and reactions are unaffected by enzymes, DTT, and AET?
a. antibody against Gill
b. anti-k
c. anti-SC1
d. anti-co(a)
a. antibody against Gill
Anti-McCb is suspected in an African American patient. What may be employed to aid in antibody identification?
a. Recombinant CR1 reagent to inhibit reactivity
b. Recombinant CR1reagent to ehance reactivity
c. Chloroquine diphosphate to inhibit reactivity
d. Chloroquine diphosphate to enhace reactivity
a. Recombinant CR1 reagent to inhibit reactivity
An antibody identification panel is performed on the serum of a patient who has a history of previous antibodies. 11 cells and an auto control are tested. 2 of the 11 cells are weakly positive, and the auto control is negative. 5 type specific RBCs were crossmatched, and one unit was weakly positive at the AGT phase of the crossmatch, and the other 4 were compatible.
Which of teh following antibody specificities below is the most likely cause for these results?
a. anti-JMH
b. anti-Bga
c. anti-Cha
d. anti-Yta
anti-Bga
The other antibodies listed or HTLA antibodies, and have higher frequencies.
A Native American woman who is group A Positive delivered a group O Rh positive infant. The baby was noted to be jaundiced 6 hours after birth and had a 3+ DAT. The mother’s antibody screen had been negative before delivery and an eluate prepared form the infant’s cells was also non-reactive with a routine antibody ID panel, A1 and B cells.
Which of of the following cells should be tested to possibly assist in identification of the antibody?
a. Do^a
b. Di^a
c. Ch^a
d. Co^a
b. Di^a
The clues here are as follows: You want to look for an antibody that is capable of causing a significant HDFN.
Anti-CH^a is an antibody with high titer, low avidity (HTLA) characteristics. The antigen is not an integral part of the RBC membrane but rather is formed in the fluids and absorbs onto the RBC. The antibody has weak reactivity and a low binding ability. The antigens are not fully developed at birth and the antibody is weak and not capable of causing HDFN. So you can rule out that antibody right away. In addition, you would likely see weaker reactions at AHG in the mom’s serum tested with the antibody panel, and the infant DAT would be negative.
Do^a is an antigen that is expressed as part of the RBC membrane, anti-Do^a can cause HTR, but does not typically cause HDFN. The antigen is present on about 65% of individuals from Northern European descent, so again, the antibody would likely react in a routine antibody ID panel.
Co^a is a high frequency antigen, so an anti-Co^a in the eluate would have reacted with all panel cells and the A1, B cells as well. IT would also show up in the serum. Anti-Co^a IS capable of causing HDFN, but the pattern of reactivity here does not correspond to the results for this situation.
Di^a is a low prevalence antigen in Caucasians, African Americans, African individuals and European individuals. The antigen is positive in approximately 11% of Native Americans, about 2% in South Americans, 12% in Japanese, 5% in Chinese, and 1% in Hispanic populations. The antibody is capable of causing of causing HDFN. So the pattern displayed in this case is consistent with the antigen and antibody. It is likely that the panel cells are lacking Di^a antigen since the majority of donors (of blood components and reagent RBCs tend to be Caucasian).
In a case like this, you would want to focus on testing cells positive for low prevalence antigens. You could also test the father’s cells to determine if it is in fact an antibody causing hemolysis, but the strong positive DAT (3+) already tells you that there is an antibody present. SO testing the father’s cells in a case where the DAT is so strong is not likely to give you additional information.
What statement is true concerning the Cartwright antigens?
a. The Yt^a antigen is a strong immunogen and examples of Anti-Yt^b are common.
b. Cord blood tests as Yt^a negative
c. The Yt^a is inherited as a dominant allele, and can inhibit the production of the Yt^b antigen.
d. Yt^b is a high frequency antigen.
b. Cord blood tests as Yt^a negative
Yt^a and Yt^b are antigens in the Yt system also known as the Cartwright system. Yt^is the high frequency antigen, and Yt is the low frequency antigen. They are co-dominant which means if inherited, both antigens are expressed. The antigens are developed at birth, but cord cells are much weaker expression than adult cells, and cord cells typically type as antigen negative.
Examples of Yt^a are reported, and can cause shortened RBC survival post transfusion, although the clinical significance varies greatly among examples of anti-Yt^a.
Anti-^b is extremely rare, even in individuals who are transfused with Yt^b cells, so Ytb is not immunogenic.
This is another example of a a typical SBB question. We know that Yt^a is weakly expressed at birth, so we might be thinking that they are serologically Yt+. However, because of the weak expression, cells in the nonate type as Yt+ We need to be able to rule out unlikely answers based on a process of elimination. Because we know the other statements are NOT true, and we know that cord blood reacts weaker, then we are only left with the answer that the cells type as Yt^a-.
