ABO Blood Groups Flashcards
ABO Allele Theories - Bernstein
3 Allele Theory
A - AA, AO
B - BB, BO
AB - AB
O - OO
ABO Allele Theories -Thompson
4 Allele Theory
A1 - A1A1, A1,O, A1A2
A2 - A2A2, A2O
A1B - A1B
A2B - A2B
ABO Phenotype in Asians
A - ___%
B - ___%
AB - ___%
O - ___%
**ABO Phenotype in Asians
A - 28%
B - 26%
AB - 5%
O - 41%
Attachment of precursor substance
Ceramide
Precursor substance
Paragloboside/Glycan
Composition of Precursor Substance
Glucose - D Galactose - N acetylglucosamine - D Galactose
Precursor Structure
H antigen
Coding of ABO Genes
Long arm of Chromosome 9
Precursor Oligosaccharide Chains in RBCs
Type:
Linkage:
Controlling genes:
Precursor Oligosaccharide Chains in RBCs
Type: Type 2
Linkage: B linkage 1,4
Controlling genes: H, A, B
Precursor Oligosaccharide Chains in Plasma/Proteins
Type:
Linkage:
Controlling genes:
Precursor Oligosaccharide Chains in Plasma/Proteins
Type: Type 1
Linkage: Beta linkage 1,3
Controlling genes: H, Se, Lewis, A, B
Secreted substances are secreted by GLYCOPROTEINS
Dominant Sugars - Type A
N-acetylgalactosamine
Dominant Sugars - Type B
D-Galactose
Dominant Sugars - H gene
L-fucose
Amorph Gene
O gene
H antigen
No. of Subtypes:
Subtypes:
H antigen
No. of Subtypes: 4 subtypes
Subtypes: H1, H2, H3, H4
Amounts of H antigen
O > A2 > B > A2B > A1 > A1B
ABO Antibodies
Group O
Anti-A (IgM)
Anti-B (IgM)
Anti-A,B (IgG - predominant)
ABO Typing Principle
Hemagglutination
Forward Typing (ABO)
Specimen:
Reagent:
Forward Typing (ABO)
Specimen: 1 drop RBC suspension (2-5%)
Reagent: 2 drops Anti-sera
Use of Anti-A,B reagent
- Check anti-A, and anti-B reagents reactions.
- Detect weak subgroups
Test for Determination of Secretor Status
Hemagglutination Inhibition
Positive Reaction: No agglutination
Color Characteristic of ABO Reagents
Anti-A
Anti-B
Anti-A,B
Color Characteristic of ABO Reagents
Anti-A - Blue
Anti-B - Yellow
Anti-A,B - Colorless
Lectins - Ulex Uropaeus
Anti-H
Lectins - Dolichos bilflorus
Anti-A1
Lectins - Griffonia simplicifolia
Anti-B
Grading of agglutination reactions:
Forward: ______
Reverse: ______
Grading of agglutination reactions:
Forward: 3+ - 4+
Reverse: 2+ - 4+
Any reactions weaker than the standard agglutination is a DISCREPANCY
*General rule: Always drop clear solutions first and RBCs second to make
One solid aggregate, Clear background
4+
Several Large aggregate, Clear background
3+
Medium size aggregates, Clear background
2+
Small agglutinates, Turbid background
1+
Tiny agglutinates, Turbid background
w+
No agglutination/Hemolysis
0+
Bombay Phenotype
Type O
Bombay Genotype
hh/Hnull
Confirms Bombay Phenotype
Ulex uropaeus - Anti-H
Para-bombay Phenotype
A bombay phenotype with normal expression of Secretions: hh Sese
A Subgroups
A1
A2
No. of antigens in A1
2 antigens: A, A1
No. of antigens in A2
1 antigens: A
Population Frequency
A1: ___%
A2: ___%
Population Frequency
A1: 80%
A2: 20%
Use to differentiate A1 and A2 subgroup
Anti-H
Anti-A1 lectin (Dolichos biflorus)
Group A subgroup that forms anti-A1
Subgroup A2
Forms anti-A1
A2: ___%
A2B: ___%
Forms anti-A1
A2: 1-8%
A2B: 22-35%
Other A subgroups upon RBC reactions with Anti-A, and Anti-A,B:
Weak agglutination:
No agglutination:
Other A subgroups upon RBC reactions with Anti-A, and Anti-A,B:
Weak agglutination: A3, Ax, Aend
No agglutination: Am, Ay, Ael
Test to perform after no agglutination in RBC reaction with Anti-A, and Anti-A,B to detect other subgroups.
Adsorption and Elution Test
A3
mf agglutination
Ax
w+ agglutination with anti-A,B only
Aend
<10% rbc show mf agglutination
Am
Quantities of A substance in saliva
Ay
Small quantities of A substance in saliva
Ael
Secretors contain H substance only
No A substance in saliva
B3
mf agglutination
Bx
Agglutination with Anti-A,B
Weak agglutination or 0+ with anti-B
Most common Technical Error in ABO Discrepancies
Clerical errors
Group 1 Discrepancies
Weak/Missing ANTIBODIES
Group II Discrepancies
Weak/Missing ANTIGENS
Group III Discrepancies
Increase Plasma Proteins resulting to Rouleau Formation
Group IV Discrepancies
Abnormal antigens (extra antigens) and presence of autoantibodies or alloantibodies both in F/R typing
Identify Discrepancy
Patient cells: Anti-A, neg Anti-B, 4+
Patient serum: A1 cells, neg B cells, neg
Group I Discrepancy
Causes of Group 1 Discrepancy
Newborn
Elderly
ABO subgroups
Immunodeficiency
Identify the discrepancy:
Anti-A 4+, anti-B 1+
A1 cells neg, B cells 4+
Group II Discrepancy: Acquired B Phenomenon
Causes of Group II Discrepancy
Acquired B phenomenon
Leukemia
Hodgkin’s disease
Subgroups A or B
Group with presence Acquired B phenomenon
Group A
Acquired B phenomenon
Phenotype:
- Forward:
- Reverse:
Acquired B phenomenon
Phenotype:
- Forward: AB
- Reverse: A
Mechanism of Acquired B Phenomenon
Modification of N-acetylgalactosamine by bacterial enzyme “deacetylase” removing acetylgalactosamine and converting to D-galactosamine that is similar to B antigen which cross-react with anti-B antisera
Remedy of Acquired B phenomenon
Use Monoclonal Ab (ES4)
Treat RBCs with Acetic Anhydride
Workup for Group I and Group II Discrepancies
Incubate Serum with A1 and B cells at RT (15-30 minutes) > No Reaction (ALL NEGATIVE) > Incubate at 4C
Identify the Discrepancy?
anti-a: 4+ anti-b: 2+
a1cells: 2+ b cells:4+
Group III Discrepancy
Causes of Group III discrepancy
High Globulins, Fibrinogen
Plasma Expanders
Wharton’s Jelly in Cord Blood
Remedy - Group III Discrepancy
Saline Replacement Technique
Causes of Group IV Discrepancy
Polyagglutination
Cold Reactive autoantibodies
Cis AB Phenotype
Unexpected ABO isoagglutinins
Polyagglutination: T activation, Tn, and HEMPAS
Nonspecific agglutination of RBcs with all anti-sera due to altered RBCs from bacterial enzymes that exposes antigens that are normally hidden.
Confirmation of Polyagglutination
- Agglutination with most ALL ADULT SERA
- NO agglutination in CORD SERA
Remedy for Group IV - Cold Reactive Autoantibodies
Case: All forward and reverse ABO results as well as the autocontrol are positive
RBC sample
1. Incubate for 37C
2. Wash with warm saline
3. Retype
Serum sample - PREWARMING Technique
1. Warm at 37C
2. Read
3. if NEG > Cold autoadsorption
Cis AB Phenotype
anti-A: w+
anti-B: w+
Inheritance of an AB Mother and O Father.
Genotype: A, B, O
Phenotype - AB