Fc receptor for immune effector cell (FcR)

Fc receptors (FcRs) are a family of cell surface glycoproteins expressed predominantly on hematopoietic cells (such as macrophages, neutrophils, natural killer (NK) cells, and some B cells) that bind the Fc (constant) region of immunoglobulins (antibodies). Their primary function is to translate antibody binding to target antigens into cellular effector functions—such as phagocytosis, antibody-dependent cellular cytotoxicity (ADCC), degranulation, and modulation of cytokine release—thereby linking humoral and cellular immune responses. Fc receptors are subdivided based on the immunoglobulin isotype they bind: FcγRs (bind IgG), FcαRs (bind IgA), FcεRs (bind IgE), among others, each with activating or inhibitory subtypes. Genetic polymorphisms and differential expression among individuals and cell types underlie differences in immune responses and susceptibility to disease, including autoimmune disorders, infections, and cancer. FcR engagement is central to the mechanisms of action of many therapeutic monoclonal antibodies.

Other names

Fc receptorFcRFcγ receptorFc gamma receptorFcα receptorFc epsilon receptorFcγRI (CD64)FcγRII (CD32)FcγRIII (CD16)FcαRI (CD89)FcεRICD16CD32CD64CD89CD23

Engagement of FcR leads to activation or inhibition of immune effector functions (ADCC, phagocytosis, cytokine release, degranulation) Monoclonal antibody-induced cell death through recruitment of NK cells, macrophages, or neutrophils Blockade/inhibition of FcR to dampen immune complex–mediated inflammation