Major Blood Group Systems

Question 1

What is the frequency of the D antigen in Blacks and Whites respectively?

Answer 1

92% and 85%

Question 2

What are the antigen frequencies of the C and little c antigens in blacks and whites respectively?

Answer 2

blacks: only 34% big C, but 97% have little c
whites: 70% have big C!, and 80% have little c (compare to blacks! lower)

Question 3

How common is big E in blacks and in whites respectively?

Answer 3

B: only 21% W: only 30%

which is why you will see more antibodies against big E

Question 4

How common is little e in blacks and whites?

Answer 4

very common in both, 99 % and 98 % respectively

Question 5

what is the G antigen? where is it present?

Answer 5

an antigen present on most D positive but ALL big C positive RBCs; In antibody id testing anti-G acts like \anti-D plus anti-C. For transfusion not necessary to discriminate bc pt will receive C-D- blood

Question 6

what is the f antigen?

Answer 6

expressed when both little c and little e are on the same haplotype; only DCE/dce shows positive reactivity

Question 7

is the f antigen clinically significant?

Answer 7

has caused HDFN and transfusion reactions, so give either c or e negative blood bc will automatically be f negative

Question 8

IN what group are the V and VS antigens more prevalent?

Answer 8

African Americans

Question 9

Do common blood bank enzymes enhance or decrease Rh antigen reactivity? Are they saline or AHG reactive?

Answer 9

enhances; sometimes saline but mainly AHG

Question 10

warm-autoantibodies often appear to have what Rh antigen specificity?

Answer 10

little e

Question 11

what are the antigen frequencies of K and k in blacks and whites?

Answer 11

K: rare in blacks, ~9% in whites

little k: 100% in blacks, 98.8% in whites

Question 12

which Kell antigens are high frequency?

Answer 12

little k, Kp^b, Js^b, Kx.

Question 13

how do common enzymes in blood bank affect Kell antigens? what about ZZAP, AET?

Answer 13

common enzymes have no effect; AET and ZZAP decrease reactivity

Question 14

how do enzymes such as ficin and papain modify the RBC surface?

Answer 14

they remove sialic acid residues and denature or remove glycoproteins

Question 15

what is ZZAP and what does it remove or modify?

Answer 15

combo of papain and dithiothreitol; removes antibodies, complement, Kell, M and N, and Duffy a and b. ZZAP used mostly in reference lab warm-auto workups

Question 16

what is DTT ? what other reagents are similar?

Answer 16

dithiothreitol, a sulfhydryl reagent that dissolves disulfide bonds between cysteine amino acids; AET (2-aminoethylisothiouronium bromide ) and 2-ME (2-mercaptoethanol)

Question 17

when is DTT useful?

Answer 17

it eliminates IgM but mostly leaves IgG; can eliminate Kell, and can eliminate panagglutination caused by the anti-CD38 monoclonal therapy daratumumab (called DARA) but must give K- blood since can’t test for it afterwards

Question 18

what are the frequencies of Duffy a and b in blacks and whites?

Answer 18

Duffy a: 65% in whites and only 10% in blacks!

Duffy b: 80% in whites and only 23% in blacks

Question 19

frequencies of the KIdd antigens in whites and blacks

Answer 19

Jka: 77% in whites, 91% in blacks
Jkb: 73% in whites, only 43% in blacks

Question 20

compare enzyme treatment effects on Duffy vs Kidd antibody reactivity

Answer 20

Duffy: destroyed
Kidd: enhanced!!!

Question 21

which antibodies are notorious for causing DHTRs and why

Answer 21

Kidd; they go low-titer quickly, becoming undetectable, but will build up again if patient exposed