HUMAN-IGG FC RECEPTOR HETEROGENEITY - MOLECULAR ASPECTS AND CLINICAL IMPLICATIONS

Receptors for the Fc domain of IgG (FcgammaR) provide a critical link between specific humoral responses and the cellular branch of the immune system. When hFcgammaR interact with immunoglobulin, a variety of biological responses are triggered. These include phagocytosis, endocytosis, antibody-dependent cellular cytotoxicity (ADCC), release of inflammatory mediators, and enhancement of antigen presentation. In the last few years our understanding of the Fcgamma receptor structure has increased dramatically, due to the availability of monoclonal antibodies (mAb) and cDNA probes. FcgammaR are members of the immunoglobulin superfamily and three main classes, hFcgammaRI, hFcgammaRII, and hFcgammaRIII are recognized in man1-3 generating at least 12 different isoforms. A further level of complexity is introduced by various genetic polymorphisms and, importantly, recent evidence points at the relevance of this FcgammaR heterogeneity.