Fc gamma receptors I, IIa, and III (FcγR)

Fc gamma receptors (FcγRs) are a group of cell surface glycoproteins that bind the Fc portion of immunoglobulin G (IgG) antibodies, serving as a critical bridge between the adaptive and innate immune systems. FcγRI (CD64) is a high-affinity receptor primarily expressed on monocytes and macrophages, while FcγRIIa (CD32a) and FcγRIII (CD16) are low-to-medium affinity receptors found on various leukocytes, including NK cells and neutrophils. These receptors trigger essential immune functions such as phagocytosis, degranulation, and antibody-dependent cellular cytotoxicity (ADCC) upon binding to immune complexes. In therapeutic contexts, FcγRs are the primary mediators of the efficacy of monoclonal antibodies used in oncology, where they facilitate the destruction of tumor cells. Conversely, in autoimmune diseases, these receptors can contribute to tissue damage, making them targets for inhibitory strategies or competitive blockade by high-dose immunoglobulin therapy. Genetic polymorphisms in these receptors, particularly in FCGR3A and FCGR2A, are known to influence patient response to antibody-based treatments.

Other names

CD64 (FcγRI)CD32a (FcγRIIa)CD16 (FcγRIII)Receptors for the Fc region of immunoglobulin GIgG receptorsFCGR1FCGR2AFCGR3

Modulation of immune effector functions through binding of the Fc region of IgG antibodies; enhancement of ADCC/ADCP in oncology; competitive inhibition or saturation of receptors in autoimmune therapy.