[4] CHAPTER II LESSON 2 Flashcards
2Represents phenotypes that show weaker variable serologic reactivity with the commonly used human polyclonal anti-A, anti-B, and anti-AB reagents.
ABO SUBGROUPS
The weaker serologic reactivity of ABO subgroups is attributed to the decreased number of [?] on their red cells.
A and B antigen sites
In 1911, [?] descried two different A antigens based on reactions between group A RBCs and anti-A and anti-A1.
von Dungern
Cause discrepancies in [?].
ABO testing and cross matches
Group A RBCs that react with both [?] are classified as A1
anti-A and anti-A1
Those that react with [?] and not anti-A1 are classified as A2.
anti-A
Classification into A1 and A2 cells account for [?] of all group A individuals
99%
BLOOD GROUP A1 ANTI-A REAGENT
+
BLOOD GROUP A1 ANTI-A1 LECTIN REAGENT
0
BLOOD GROUP A2 ANTI-A REAGENT
+
BLOOD GROUP A2 ANTI-A1 LECTIN REAGENT
+
Differences in the precursor oligosaccharide chains
↓ Number of antigen sites
Subtle differences in transferase enzymes
↓ Amount of transferase enzyme
Formation of anti-A1, in a percentage of some subgroups
↓ Amount of branching
The immunodominant sugar on both A1 and A2 RBCs is
N-actylD-galactosamine
Differentiation of A1 and A2 phenotypes can be determined by using a reagent made from the seeds of the plant
Dolichos biflorus
is found in greatest concentration on the RBCs of O individuals
H antigen
Reactivity of anti-H antisera or anti-H lectin with ABO blood groups:
O > A2 > B > A2B > A1 > A1B
- agglutinates A1 or A1B
- Dolichos biflorus
agglutinates B cells
- Bandeiraea simplicifolia
- agglutinates O cells (H specificity) and other ABO blood groups depending on the amount of H antigen available
- Ulex europaeus
In accordance with Landsteiner’s rule for expected ABO antibodies, sera from group O and B individuals contain
anti-A antibodies.
The anti-A produced by group O and B individuals can be separated by adsorption and elution techniques into two components:
anti-A and anti-A1
is specific for the A1 antigen and does not agglutinate A2 red cells
Anti-A1
The optimal reactivity of this antibody is at room temperature or lower.
AntiA1
is not considered clinically significant for transfusion purposes
AntiA1
becomes a concern when it causes problems with ABO phenotyping results and incompatible crossmatches on immediate spin
AntiA1
does not exist because the A2 phenotype possesses the same A antigens as A1 phenotype but in reduced quantities.
Anti-A2
Individuals with A1 phenotype do not respond immunologically when exposed to
A2 red cells.