Introduction, ABO, RH Flashcards
1
Q
What are the primary immunological components?
A
antigens & antibodies
2
Q
Provides basis for blood bank testing and reactions
A
antigens & antibodies
3
Q
Cardinal rule in blood bank
A
The antigens are found on the surface of red blood cells and the antibodies are found in serum or plasma
4
Q
Substances that have the capability to stimulate the production of an antibody
A
Antigens
4
Q
Characteristics of an antigen
A
- Chemical nature
- Molecular weight
- Complexity
- Stability
- Foreign
4
Q
Chemical composition of antigens:
A
- Glycoproteins
- Glycolipids
- Pure Polysaccharides
- Pure lipids & Nucleic acids
5
Q
Immunogenicity of Blood Group Antigens (from most immunogenic to least)
A
- A, B, and D (Rho)
- Kell (K)
- Duffy: Fya and Fyb
- Kidd: Jka and Jkb
6
Q
Not immunogenic but
can be antigenic; serve as haptens
A
Pure lipids & nucleic acids
7
Q
Not immunogenic except in humans and mice
A
Pure polysaccharide
8
Q
Also called immunoglobulins, agglutinins
A
Antibodies
9
Q
Characteristics of an antibody
A
- Protein
- Produced in response to stimulation by an antigen
- Specific for the stimulating antigen
10
Q
Antibodies consist of 2 heavy chains & 2 light chains held together by?
A
disulfide bonds
11
Q
Three fragments of antibodies produced when cleaved by enzymes
A
2 Ag binding fragments (Fab) & 1 crystallizable fragment (Fc)
12
Q
Classification of Blood Group Antibodies
A
Alloantibodies and Autoantibodies
13
Q
Reacts with foreign Ag not present on patient’s own RBC
A
Alloantibodies
14
Q
Most produced as result of immune stimulation via transfusion or pregnancy (usually during delivery)
A
Alloantibodies
15
Q
Reacts with an Ag on patient’s own cells & with the same Ag on the same Ag on the cells of other individuals
A
Autoantibodies
16
Q
Single most important blood group for the selection and transfusion of blood
A
ABO blood group
17
Q
Who discovered ABO blood group?
A
Karl Landsteiner
18
Q
ABO blood group is expressed/found in?
A
tissues & body fluids including red cells, platelets & endothelial cells
19
Q
What are the three antigens of ABO blood group?
A
A, B, H
20
Q
What are the two major antibodies of ABO?
A
Anti-A and Anti-B
21
Q
What are the four phenotypes of ABO?
A
A, B, AB, O
22
Q
Present on the surface of red cells as well as tissue and endothelial cells in the body
A
ABO Antigens
23
Found in soluble form in plasma & other body secretions in people known as secretors
ABO Antigens
24
ABO Antigens are inherited in simple _______ from individual's parents
Mendelian fashion
25
3 possible ABO genes that can be inherited
A, B, O
26
These genes produce a detectable product
A and B genes
27
This gene does not produce a detectable product
O gene
28
A and B genes do not directly produce antigens, instead they produce an enzyme called
transferase
29
Attaches a sugar molecule to the chemical structure of the antigen
Transferase
30
The only ABO antigen that has no transferase, thus does not produce an antigen
O gene
31
Protrude from outermost layer of cell membrane
A and B antigens
31
Enumerate the immunodominant sugar for each antigen under the ABO blood group (A, B, H)
* H antigen: fucose/ fucosyl
* A antigen: N-acetylgalactosamine/ N-acetylgalactosaminyl
* B antigen- D-galactose/ D-galatosyl
32
To produce either A or B antigen this is required
H antigen
33
Possible genetic combinations of H antigen
HH, Hh, hh
34
Genetic combination that produce H Ag (99.99% of
Caucasians)
HH or Hh (+)
35
Genetic combination that does not produce H Ag
hh
36
hh genetic combination is found in people who have?
Bombay phenotype (Oh)
37
Found only in individuals
with Bombay phenotype
anti-H
38
Frequencies of ABO Blood Groups
O- 45%
A- 41%
B- 10%
AB- 4%
39
Enumerate the ABO Subtypes
1. A variants (A1, A2)
2. Weak A and weak B phenotypes
3. Null phenotypes: a) Bombay (Oh) b) Para-Bombay
40
No A, B or H Ag on red cells & secretions. With anti-A, anti-B & anti-H in their sera
Bombay (Oh)
41
Absent or only trace A,B & H Ag’s detected
on rbc w/ normal expression in secretions & body fluids
Para-Bombay
41
Natural antibodies, antigenic stimulus is environmental, exposure occurs from birth
ABO Antibodies
41
Newborns are born without ABO antibodies of their ow, only begin to produce Ab with detectable titer at?
6 months of age
42
Other characteristics of ABO antibodies:
1. IgM
2. Reacts at room temp. after an immediate spin
43
Test for antigens, patient’s cells containing unknown antigens tested with known antisera
Direct or Forward Typing
44
In Direct or Forward Typing, the antisera is manufactured from?
human sera
45
Separate Ab that reacts with both A and B antigen
Anti-A,B
46
Anti-A,B is used in forward grouping for two purposes:
1. confirms the results of the anti-A and anti-B
2. will show a (+) reaction with weak subgroups of A and B that do not react with the anti-A and anti-B
46
Known antigen (cell) vs. unknown antibody
(patient’s serum)
Indirect or Reverse Typing
47
Ratio in Indirect or Reverse Typing
2:1 (2 drops of serum/plasma and 1 drop red cells)
48
Uses commercially prepared reagents containing saline-suspended A1 and B cells
Indirect or Reverse Typing
49
Identify the Stage of Hemagglutination: Formation of stable latticework which is the basis of visible reaction
Second stage
50
Identify the Stage of
Hemagglutination: Red cell sensitization
First stage
51
Identify the Stage of Hemagglutination:
- Ag and Ab held by non-covalent interactions
First stage
52
Identify the grading of agglutination: Several large aggregates
3+
53
Identify the grading of agglutination: Few small aggregates visible macroscopically
1+
54
Identify the grading of agglutination: One solid aggregate
4+
55
Identify the grading of agglutination: No clumps or aggregates
Negative (0)
56
Identify the grading of agglutination: Tiny clumps or aggregates barely visible macroscopically or to the naked eye
Weak (+/-)
57
Causes of Discrepancies in ABO Testing: Serum
1. Roleaux formation
2. Anti-A1
3. Unexpected alloantibodies
4. Expected antibody absent
57
Identify the grading of agglutination: Medium-sized aggregates
2+
57
Causes of Discrepancies in ABO Testing: Red Blood Cells
1. Missing or weak A/B antigen
2. Acquired B Ag
3. Polyagglutinable RBC
4. Ab-coated RBC
5. Maternal-fetal agglutination
57
Causes of Discrepancies in ABO Testing: Technical
1. Incorrect ID/recording
2. Patient/donor serum not added
3. Reagent contamination
4. Under-/over-centrifugation
5. Hemolysis
6. Warming of test mixture
57
This discrepancy is caused by the presence of plasma expanders,
monoclonal gamma globulins
Roleaux formation (serum)
58
This discrepancy is caused by hypogammaglobulinemia, extreme ages, immunosuppression
Expected antibody absent (serum)
59
This discrepancy is caused by colon or gastric CA, intestinal obstruction
Acquired B Ag (Red blood cells)
60
This discrepancy is caused by mismatched transfusion
Maternal-fetal agglutination
61
This discrepancy is caused by post-transfusion incompatibility;
autoimmune hemolytic anemia
Ab-coated hemolytic anemia
62
How to remedy when discrepancy arises in ABO testing
1. Wash cells with saline 3-4x and repeat all tests and test for antibodies
2. Test for subgroups of Ausing anti-A1 and anti-A
3. Use cell panels to detect the specificity of abnormal antibodies
63
Discovered in 1940 by Landsteiner & Wiener
Rh Blood Group
64
Rh Blood Group is the **most complex erythrocyte antigen system**;
located on?
chromosome 1
65
Found **exclusively** on surface of rbc
Rh Blood Group
66
What does the Rh blood group lacks that the ABO has?
corresponding naturally-occurring antibodies in serum
67
Integral part of red cell membrane
Rh blood group
68
Classification/Nomenclature System of Rh Blood Group
1.) Wiener
2.) Fischer & Race (most commonly used)
3.) Rosenfeld
69
Identify the Rh classification:
- Multiple allele hypothesis.
- 5 antigens: Rho, rh’, rh”, hr’, hr”
Wiener
70
Identify the Rh classification:
Single locus inheritance system with 8 alternate common alleles coding for agglutinogens. 1 individual produces 2 agglutinogens inherited from both parents
Wiener
71
Identify the Rh classification:
- Numerical system
- Rh1 to Rh5
Rosenfeld
72
Identify the Rh classification:
- Three alleles: D/d, C/c and E/e
- Five antigens: D, C, E, c, e
- d -> no D locus, which means no antigenic products
Fischer & Race
72
What are the three integral membrane proteins of Rh antigens
1. RhD
2. RhCcEe
3. Rh-associated glycoprotein (Rh50, RhAG)
72
Resides in RhD protein, most
immunogenic
D antigen
73
Enumerate the Rh antigens from most to least immunogenic
D, c, E, C, e
74
Weak D Antigen (Du) is also known as?
Rho variant
74
It is a weak or absent red cell agglutination by anti-D, detected only with use of anti-human globulin reagent
Weak D Antigen (Du)
75
Weak D Antigen (Du) is weakened and is caused by 1 of 3 situations:
1. a piece of the D antigen is missing
2. D gene is on a chromosome opposite a C gene
3. Inheritance of a gene coding for less D antigen
76
What reagent is used for testing for Du variant
**bovine or albumin-suspended** anti-D reagent
77
For testing for Du variant how many minutes and at what temperature should it be incubated for?
incubate at **37C for 15-60 minutes** (to facilitate formation of Ag-Ab complex)
77
These people should be proven to be Du (-) before they are considered to
be eligible to receive transfusion
women who appear to be Rh (-)
77
(+) Du is considered to be?
Rh positive (+)
78
Testing for Rho (D) Antigen you should use antisera that has?
high protein media
*(necessary to produce agglutination since antigens are an integral part of the red cell membrane)*
79
These are not naturally occurring immune antibodies that are produced upon sensitization, and has IgG isotype
Rh antibodies
80
Identify:
- Reactive at 37C
- Enhanced with enzyme-treated red cells
- Can cross the placenta
- Associated with hemolytic transfusion reaction
and hemolytic disease of the newborn (HDN)
Rh antibodies
81
Causes of False (+) results in Rh typing include:
1. Drying
2. Roleaux formation
3. Auto-agglutination
4. Patient’s red cells heavily coated with Ab’s
5. Presence of cold agglutinins
82
Causes of False (-) results in Rh typing include:
1. Use of old cells
2. Wrong cell concentration
3. Hemolysis
4. Inadequate mixing of cells
5. Inactive typing sera
6. Incorrect temperature
7. Existence of Du variant
8. High concentration of blocking antibodies
83
Cite the other two rules in blood bank
1. If you have A/B/O blood group, **naturally you do not produce antibody** against the A/B/O antigen
2. If you have A antigen, you **will naturally produce B antibody**
