Flashcards in 6. ABO and Rh Discrepancies Deck (23):
Most common ABO discrepancy?
No reverse typing rxns
May be seen in bone marrow or transplant recipients
4 'B' subgroups
B3, Bx, Bm, Bel
What reagent is used to distinguish A1 from A2 red cells?
Dolichos biflorus lectin (=anti-A1)
Strong rxn w/ _____ proves that it is not Bombay phenotype
2 possible causes of additional antibodies in serum/plasma?
Reasons for A1 reverse reacting positively discrepancy?
Probable A2 subgroup with anti-A1
% of A1 and A2 individuals?
80% A1 or A1B
20% A2 or A2B
Cause of B(A) phenotype
Group B individuals have trace amounts of A antigen
What change causes acquired B phenotype?
Bacterial enzyme alters A sugar to resemble B sugar = cross-rxn
This subgroup has strong agglutination reactions w/ anti-H
Other A subgroups (A3,Ax, Aend, Am, Ay, Ael)
How to resolve a positive Rh control?
Repeat w/ washed patient cells
Most likely reason for no reverse typing rxns?
Patient - old age
Why does A2 subgroup have less A antigen than A1?
A2 gene's transferase is less efficient at converting H to A substance
Associated w/ multiple myeloma and Waldenstrom's macroglobulinemia
Seen in group A1 individuals with diseases of the lower GI tract, Ca of the
colon or rectum, intestinal obstruction, or gram-neg septicemia
Acquired B phenotype
What are ABO subgroups?
Phenotypes that show weaker variable serological reactivity with the commonly used human polyclonal Anti-A, Anti-B, and Anti-A,B reagents
Subgroup suggested by seeing mixed field
What characterizes mixed field rxns?
Fwd grouping is weak and mixed field; reverse is fine
What is used to agglutinate B cells?
Bandeiraea simplicofolia (anti-B)
Resolution for cold autoantibody or alloantibodiy
Perform antibody screen w/ autocontrol