Duffy Blood Group System

• Duffy Blood Group System has an ISBT no. 008 and symbol FY
• Duffy (Fy) System Antigens the gene ACKR1 (atypical chemokine receptor 1) is located on chromosome 1
• 5 Fy system antigens:

  • Fya,
  • Fyb,
  • Fy3
  • Fy5
  • Fy6
• Fy (a-b-) resists infection in vitro by the monkey malaria organisms Plasmodium knowlesi and resist infection by Plasmodium vivax
• Fy (a-b-) are also Fy:-3,-5
• Fy5 is also not present on Rh null RBCs, regardless of Fya and Fyb status
• Duffy Antigens (Fya and Fyb) can be identified on fetal RBCs as early as 6 weeks gestational age; well developed at birth.
• Duffy Antigens are not found on platelets, lymphocytes, monocytes or granulocytes, but they have been identified in other body tissues (brain, colon, endothelium, lung, spleen, thyroid, thymus, and kidney cells)
• Duffy Antigens are destroyed by common proteolytic enzymes such as ficin, papain, bromelin, chymotrypsin and ZZAP (contains papain or ficin in addition to DTT)
• Duffy Antigens are not affected by DTT alone, AET, or glycine-acid EDTA treatment
• Fy3 and Fy5 are resistant to proteolytic enzymes
• Anti-Fya and Anti-Fyb are usually IgG and generally, react only at the AHG phase
• Anti-Fya and Anti-Fyb often bind complement and activity is enhanced in low-ionic strength medium (LISS)
• Anti-Fya and Anti-Fyb some shows dosage effect, but both are destroyed by enzyme treatment and heating to 56C and occur more commonly in combination with other RBC antibodies
• Anti-Fya and Anti-Fyb Has been associated with acute and delayed hemolytic transfusion reactions but Anti-Fya has occasionally been implicated in HDN
• Fya – encodes the antigen Fya
• Fyb – encodes the antigen Fyb
• Fy – silent allele (Fya-b-)
• Fy(a-b-) blacks do not express Fyb on their RBCs but express Fyb in other tissues.
• Fyx - An inherited weak form of Fyb that reacts with some examples of anti-Fyb