Biology of human immunoglobulin G Fc receptors.

A heterogeneous group of receptors binding the Fc region of Ig, Fc receptors, provides important links between the cellular and humoral branches ofthe immune system. The members of this receptor group, specific for essentially all the Ig isotypes, are expressed on a variety of cells and mediate multiple important functions. Receptors for IgG (Fc’yR) , a subgroup within the larger group of FcR, were recently shown to belong to the Ig supergene family . Three major classes of leukocyte Fc R are currently recognized, all of which contain several members. Although rapid progress has been made in elucidating the structure of Fc’yR and organization of their genes [see 107] , many questions about the functions of these Fc’yR remain unanswered. In this review we focus on the various biological functions mediated by the different human Fc’yR. We utilize a new nomenclature for these receptors recently proposed by other workers (Kinet, J.-P. and Ravetch, J. , personal communication).