Immunoglobulin gamma Fc receptor (FcγR)

Immunoglobulin gamma Fc receptors (FcγRs) are a family of cell surface receptors that bind the Fc region of immunoglobulin G (IgG) antibodies[1][8][4]. They serve as a crucial interface between humoral and cellular immunity by enabling leukocytes (such as macrophages, neutrophils, natural killer cells, and B cells) to recognize and respond to antibody-tagged pathogens or cells[1][7][8]. FcγRs are divided into three main classes in humans—FcγRI (CD64), FcγRII (CD32), and FcγRIII (CD16)—which differ in their structure, affinity for IgG, signaling motifs, and functional roles[4][8]. These receptors can be activating (containing immunoreceptor tyrosine-based activation motifs, ITAMs) or inhibitory (such as FcγRIIB, containing immunoreceptor tyrosine-based inhibitory motifs, ITIMs), allowing for tight regulation of immune cell responses[1][4][7]. The interaction of IgG antibodies with FcγRs triggers diverse effector functions, including phagocytosis, cytotoxicity, inflammatory mediator release, and modulation of the immune response[4][1][7]. FcγRs play important roles in protection against infection, clearance of immune complexes, the therapeutic action of many antibody drugs, and pathogenesis of autoimmune and inflammatory diseases[1][4][7][8].

Other names

Fc gamma receptorFcγ receptorIgG Fc receptorCD64 (FcγRI)CD32 (FcγRIIa, FcγRIIb, FcγRIIc)CD16 (FcγRIIIa, FcγRIIIb)

Engagement of FcγR mediates clearance of antibody-coated cells via phagocytosis or ADCC[7][4]. Modulation of immune activation (either activating or inhibitory signaling depending on receptor subtype)[1][7]. Cytokine release and enhanced antigen presentation.