Duffy Flashcards
Duffy antigen location
Atypical chemokine receptor 1
Binds cytokines, especially IL-8; role in inflammation
Duffy gene (ACKR1) location
Chromosome 1q21-q22
How many Duffy antigens
5
Fya/b, Fy3, Fy5, Fy6
(Fy4 is obsolete)
Duffy phenotype frequency
Whites
Fy(a+b-): 20%
Fy(a+b+): 48%
Fy(a-b+): 32%
Fy(a-b-): 0%
Duffy phenotype frequency
African Americans
Fy(a+b-): 10%
Fy(a+b+): 3%
Fy(a-b+): 20%
Fy(a-b-): 67%
Duffy phenotype frequency
Asia
Fya is high prevalence
Fy(a+b-): 81%
Fy(a+b+): 15%
Fy(a-b+): 4%
Duffy antigen characteristics
Well developed at birth
Found on rbcs as well as endothelial cells, brain, colon, lung, spleen, kidney, etc
Weaken with storage
Duffy a/b antigen on treated RBCs
Destroyed by enzymes (bromelin, ficin, papain, pronase, a-chymotrypsin) and ZZAP
Resistant to trypsin
Fy(a-b-) in whites
Uncommon
Usually true null
No expression on RBCs or tissues
Can make anti-Fy3
Fy(a-b-) in blacks
Usually Arises from silencing mutation in the promoter region of the Fyb allele
Prevents expression on RBCs but still present on other tissues
Rarely make anti-Fyb or -Fy3
Anti-Fya/b
Usually IgG
Do not bind complement well
Show dosage
Clinically significant
Fy3, Fy5, Fy6 reactivity with enzyme treatment
Fy3 resistant
Fy5 resistant
Fy6 destroyed
Anti-Fy3
Found in Fy(a-b-) individual
Reacts as inseparable anti-Fya and -Fyb but enzymes don’t eliminate reactions
Acute and delayed HTRs
Anti-Fy5
Doesn’t react with Fy(a-b-) RBC or Rh null (regardless of their Duffy typing)
Delayed HTRs
Anti-Fy6
Not found in humans
