Low affinity immunoglobulin gamma Fc region receptor III-A （FCGR3A） is a receptor for the Fc portion of immunoglobulin G， and is involved in the elimination of antigen-antibody complexes from the circulation， as well as other antibody-dependent responses. FCGR3A needs to associate with the gamma subunit of Fc epsilon. The FCGR3A receptor is expressed on natural killer （NK） cells as an integral membrane glycoprotein anchored through a transmembrane peptide， while FCGR3B is expressed on polymorphonuclear neutrophils （PMN） where the receptor is anchored through a phosphatidylinositol （PI） linkage. In addition， FCGR3A is expressed on macrophages， subpopulation of T-cells， immature thymocytes and placental trophoblasts. FCGR3A mediates antibody-dependent cellular cytotoxicity （ADCC） and other antibody-dependent responses， such as phagocytosis. FCGR3A gene mutations are linked with susceptibility to recurrent viral infections， susceptibility to systemic lupus erythematosus， and alloimmune neonatal neutropenia.
