ABO subgroups Flashcards
ABO subgroups represent:
Phenotypes showing weaker and variable serologic reactivity with anti-A, anti-B, and anti-A,B reagents
Cause of ABO subgroups:
Result of less effective enzymes that convert H antigens to A or B antigens
Key difference in ABO subgroups:
Amount of antigen present on the red blood cell membrane
Phenotype A1: Antigens present and population frequency
Antigens: A, A1; Frequency: 80%
Phenotype A2: Antigens present and population frequency
Antigens: A; Frequency: 20%
Reactivity of A1 individuals with anti-A (B sera) and anti-A1 lectin
Positive for both anti-A and anti-A1 lectin
Reactivity of A2 individuals with anti-A (B sera)
Positive for anti-A only
Frequency of anti-A1 formation in A2 individuals
1-8%
Frequency of anti-A1 formation in A2B individuals
0.25
Anti-H lectin reactivity comparison: A1 vs A2 RBCs
A2 shows increased reactivity with anti-H lectin compared to A1
Weak A subgroup characteristics: Antigen sites per RBC
Decreased number of A antigen sites per RBC
Weak A subgroup characteristics: Agglutination with human anti-A, B
Variable degrees of agglutination
Weak A subgroup characteristics: Detectability of H antigen
Strong reactions with anti-H due to variability in detectability
Weak A subgroup characterization methods
Secretor studies, adsorption studies, and molecular testing
Subgroups of A showing mixed-field reactions
A3, Ax, Aend
Subgroups of A with no reaction with anti-A and anti-AB
Am, Ay, Ael
Subgroup of B with mixed-field agglutination with anti-B and/or anti-A,B
B3
Subgroup of B with agglutination only with anti-A,B (weak/none with anti-B)
Bx
Subgroup of B with no agglutination with anti-B and anti-A,B
Bm, Bel
Subgroup of B with secretors demonstrating quantities of B substance in saliva
Bel
Subgroup of B with secretors containing only H substance and no B substance in saliva
Bel
Year and location of first reported H-deficient case (Bombay phenotype)
1952, Bombay, India