CD177. also known as human neutrophil antigen-2a (HNA-2a), is a glycosylphosphatidylinositol (GPI)-anchored glycoprotein predominantly expressed on neutrophils. First identified in the 1990s, it plays a role in neutrophil migration to inflammatory sites, potentially mediating interactions with endothelial cells. CD177 expression varies among individuals, with approximately 3-5% of the population lacking it (HNA-2a-negative phenotype), a trait linked to genetic polymorphisms.
CD177 binds proteinase 3 (PR3), a serine protease involved in neutrophil extracellular trap (NET) formation and inflammation. This interaction localizes PR3 to the neutrophil membrane, making CD177 a key autoantigen in ANCA-associated vasculitis (AAV), where anti-PR3 antibodies contribute to vascular damage. CD177-specific antibodies are thus critical in studying AAV pathogenesis and diagnostics.
Clinically, anti-CD177 antibodies are used to detect HNA-2a antigens in blood typing, particularly in cases of neonatal alloimmune neutropenia (NAN) or transfusion-related acute lung injury (TRALI). They also serve as research tools to explore neutrophil heterogeneity, as CD177+ and CD177− subsets exhibit functional differences in inflammation and infection. Recent studies suggest CD177 may influence tumor microenvironments, with its expression observed in certain cancers, though its role remains unclear.
Overall, CD177 antibodies are vital for understanding neutrophil biology, immune disorders, and developing targeted diagnostics or therapies.