Duffy Blood Group Antigen and White Blood Cells
The Fya (FYA) Duffy blood group antigen does not directly affect white blood cells themselves, but the Duffy glycoprotein (ACKR1) that carries these antigens is expressed on both erythrocytes and endothelial cells where it functions as an atypical chemokine receptor that modulates leukocyte trafficking and inflammatory responses.
Expression Pattern and Function
The Duffy glycoprotein is a seven-transmembrane protein that serves dual roles:
On erythrocytes: It carries the Fya and Fyb blood group antigens, which differ by a single nucleotide polymorphism (125G>A) resulting in a Gly42Asp amino acid change 1, 2.
On endothelial and epithelial cells: The same glycoprotein functions as an atypical chemokine receptor (ACKR1) that binds both C-X-C and C-C chemokines, thereby regulating leukocyte and chemokine trafficking 2, 3.
Impact on Leukocyte Function
The Duffy glycoprotein modulates the intensity of inflammatory responses by regulating chemokine availability, which indirectly affects white blood cell behavior:
Vascular endothelial cells can induce Duffy protein expression (5-8 fold increase) in response to tumor necrosis factor-alpha treatment, suggesting a role in regulating leukocyte trafficking during inflammation 3.
The protein is constitutively expressed on endothelial cells throughout the body, where it likely serves as a chemokine sink or presenter, affecting how white blood cells respond to inflammatory signals 2, 3.
Clinical Relevance for Transfusion
For patients with sickle cell disease requiring transfusions, those with the GATA mutation (FY*B-33 allele) that prevents erythroid expression of Duffy antigens are not at risk for anti-Fyb alloimmunization and do not require Fyb-negative red cells 4.
Key Points About the GATA Mutation:
The -33T>C SNP in the promoter region suppresses Duffy expression only on erythrocytes, while expression continues on endothelial and other non-erythroid tissues 1, 2.
This Fy(a-b-) phenotype is predominant in individuals of African descent (78.32% in some populations) 5.
The mutation does not eliminate the protein's chemokine receptor function on endothelial cells, so leukocyte-related functions remain intact 2.
Important Caveats
The Duffy antigen's effect on white blood cells is indirect and mediated through its chemokine receptor function on endothelial cells, not through direct interaction with leukocytes themselves. The primary clinical significance of Duffy antigens relates to: