CD32 is a 40 kD polymorphic transmembrane glycoprotein also known as FcgammaRII and FCRII. It is an immunoglobulin superfamily member expressed on monocytes/macrophages, granulocytes, platelets and B cells. There are at least 6 isoforms of CD32 resulting from alternative mRNA splicing. CD32 mediates phagocytosis and oxidative burst in granulocytes, as well as platelet aggregation and immunomodulation. The extracellular domain of CD32 binds to polymeric and aggregated IgG and immune complexes, while the intracellular domain has been reported to associate with SHP-1 (B1 isoform).