Fc receptor (FcR)

Fc receptors are a family of cell surface proteins found on various immune system cells—including B cells, T cells, macrophages, dendritic cells, neutrophils, natural killer (NK) cells and other leukocytes—that bind to the constant region (Fc) portion of antibodies attached to pathogens or infected host targets. This interaction enables these effector immune cells to recognize antibody-coated targets for elimination through processes such as phagocytosis and antibody-dependent cell-mediated cytotoxicity. Different classes exist based on immunoglobulin specificity—such as IgG-binding Fc gamma receptors (FcγRs), IgA-binding alpha receptors (FcαRs), IgE-binding epsilon receptors (FcεRs), among others—with distinct activating or inhibitory functions mediated by intracellular signaling motifs like ITAMs. Dysregulation or genetic variation in these pathways is implicated in infection susceptibility and a range of inflammatory and autoimmune diseases; thus they represent important therapeutic targets both for enhancing immunity against infections/cancer and suppressing harmful autoimmunity. Monoclonal antibodies and engineered antibody therapeutics often target or exploit Fc receptors for their mechanism of action.

Other names

Fc gamma receptor (FcγR)Fc alpha receptor (FcαR)Fc epsilon receptor (FcεR)Immunoglobulin Fc receptorIgG/IgA/IgE/IgM receptors (depending on subclass)

Modulation of immune cell activation or inhibition via antibody-Fc binding to the respective receptors on effector cells such as macrophages, neutrophils, NK cells, dendritic cells, B cells, etc. Induction of phagocytosis or ADCC by crosslinking with immune complexes bound to pathogens or target cells. Down-regulation or blockade of specific FcRs to reduce pathological inflammation in autoimmune diseases.