Low affinity immunoglobulin gamma Fc receptor IIIb (CD16b)

Fcγ receptor CD16B, also known as FCGR3B, is a low-affinity receptor for the Fc region of immunoglobulin G (IgG) that is uniquely and abundantly expressed on human neutrophils [1.3.1, 1.3.5]. Unlike its isoform CD16A, CD16B is anchored to the cell membrane via a glycosylphosphatidylinositol (GPI) linker and lacks a transmembrane or intracellular signaling domain [1.1.3, 1.3.3]. It primarily functions as a decoy receptor that captures IgG-containing immune complexes, thereby modulating the intensity of the immune response and preventing excessive neutrophil activation [1.1.3, 1.3.2]. CD16B also synergizes with other Fc receptors, such as CD32A, to facilitate the phagocytosis of opsonized pathogens [1.1.1, 1.3.2]. Genetic polymorphisms and copy number variations in the FCGR3B gene are associated with susceptibility to autoimmune diseases like systemic lupus erythematosus and rheumatoid arthritis [1.1.1, 1.3.5]. In the context of cancer immunotherapy, CD16B can compete with the activating receptor CD16A for binding to therapeutic monoclonal antibodies, potentially reducing their efficacy in inducing antibody-dependent cellular cytotoxicity (ADCC) [1.1.3, 1.3.3].

Other names

FCGR3BFCG3FCGR3IGFR3Fc-gamma RIIIbCD16B antigen

CD16b binds to the Fc region of IgG antibodies, primarily acting as a decoy receptor on neutrophils to sequester immune complexes and modulate the availability of IgG for activating receptors like CD16a and CD32a [1.1.3, 1.3.2].