The IgG Fc receptor family.

IgG immune complexes are of central importance in the humoral immune system and strongly implicated in the pathogenesis of hematologic and rheumatic autoimmune disorders. Cross-linking of receptors for the Fc domain of IgG antibodies (FcγRs) triggers a wide variety of effector functions including phagocytosis, antibody-dependent cellular cytotoxicity, and release of inflammatory mediators, as well as immune complex clearance and regulation of antibody production. In this way, FcγR provide an essential feedback between the humoral and cellular immune response. In the past, significant advances have been made in the molecular dissection of FcγR function using cellular transfection systems. Current approaches designed to target and change individual FcγR genes in mice have given further insight into their specific contributions to systemic processes, also indicating them to be important immunoregulatory receptors involved in various disease states of allergy, autoimmunity, and inflammation. Future work on targeting FcγR binding sites in combination with humanized FcγR mouse models will lead to novel therapeutic strategies in the treatment of IgG-mediated human disease in which FcγR activation plays an integral part.