Author:
Lalezari Parviz,Bayat Behnaz
Abstract
Neutrophils are the most abundant nucleated cells in blood circulation and play important roles in the innate and adaptive immune responses. Neutrophil-specific antigens, only expressed on neutrophils, are glycoproteins originally identified in studies on neonatal neutropenia due to fetal-maternal incompatibility and autoimmune neutropenia of infancy. The most investigated neutrophil–specific antigens are the NA and NB antigens that their incompatibilities also cause transfusion-induced febrile reactions and acute lung injury, a potentially fatal reaction, and in bone marrow transplantation, causing graft rejection. NA antigens are members of the immunoglobulin superfamily and are low-affinity Fc-receptors FcγRIIIb (CD16b). Fc receptors connect the F(ab), the antigen-binding fragment of the antibody molecules, to neutrophils and lead them to recognize and phagocytize the targeted antigens. The NB (CD177) antigen belongs to the urokinase-type Plasminogen Activator Receptor Superfamily (uPAR, CD59, Ly6), but its specific functions have not been fully determined. It is known, however, that NB antigen binds proteinase-3 (PR3 to the neutrophil membrane), a serine protease. In clinical studies, it was also demonstrated that NB expression is highly elevated in Polycythemia Vera and is unexpectedly expressed in some cancer tissues. Neutrophil-specific antigens are examples of antigens that have important biological and clinical activities beyond antigenicity.