Immunoglobulin G Fc receptor IIA (FcγRIIa)

Immunoglobulin G Fc receptor IIa (FcγRIIa, CD32a) is a cell-surface glycoprotein receptor expressed mainly on myeloid cells such as neutrophils, monocytes, and macrophages[1][6]. It belongs to the immunoglobulin superfamily and functions as an activating receptor by binding to the Fc region of IgG antibodies, specifically engaging immune complexes or opsonized pathogens[2][5]. Engagement triggers a signaling cascade via its immunoreceptor tyrosine-based activation motif (ITAM), leading to cellular responses including phagocytosis, oxidative burst, cytokine secretion, and antibody-dependent cellular cytotoxicity[1][5]. Variations (polymorphisms) in FcγRIIa, especially the R131/H131 alleles, modulate binding affinity to IgG subclasses and influence individual susceptibility to infectious and autoimmune diseases, as well as clinical responses to antibody therapies[5][3]. The receptor is an important therapeutic target and effector in monoclonal antibody-based immunotherapies and serves as a key interface between humoral (antibody-mediated) and cellular immunity[1][2][5].

Other names

Fc gamma receptor IIaFcγRIIaCD32aIGFR2FcgR2A

Engages Fc domains of immunoglobulin G (IgG) to trigger downstream immune cell activation through immune receptor tyrosine activation motif (ITAM) signaling Mediates phagocytosis and ADCC by linking IgG-coated targets to effector cell responses