Low affinity immunoglobulin gamma Fc receptor IIIb (FCGR3B) (FCGR3B)

Low affinity immunoglobulin gamma Fc receptor IIIb (FCGR3B), also known as CD16b, is a glycosylphosphatidylinositol (GPI)-anchored receptor expressed specifically on the surface of neutrophils [1]. It serves as a low-affinity receptor for the Fc region of IgG antibodies, playing a pivotal role in the capture of immune complexes and the initiation of neutrophil effector functions such as the oxidative burst and degranulation [2]. Unlike FCGR3A (CD16a), FCGR3B lacks a transmembrane domain and relies on association with other receptors like CR3 (CD11b/CD18) for signal transduction [3]. Genetic polymorphisms and copy number variations (CNV) of the FCGR3B gene are significantly linked to the pathogenesis of autoimmune diseases, most notably systemic lupus erythematosus (SLE) and rheumatoid arthritis [4]. In therapeutic contexts, FCGR3B is a target for intravenous immunoglobulin (IVIG) therapy, which can modulate its activity to treat inflammatory conditions [5]. Furthermore, emerging cancer immunotherapies are exploring bispecific antibodies that engage FCGR3B to recruit neutrophils for antibody-dependent cellular cytotoxicity (ADCC) against tumor cells [6]. Understanding the unique signaling and expression profile of FCGR3B is crucial for developing precision immunotherapies that leverage the innate immune system [7]. Sources: [1] UniProt (P12318); [2] PubMed (PMID: 25336632); [3] NCBI Gene (ID: 2215); [4] Nature Genetics (PMID: 16474405); [5] Journal of Clinical Investigation (PMID: 21821915); [6] Frontiers in Immunology (PMID: 30804953); [7] StatPearls (Fc Receptors).

Other names

CD16bFc gamma receptor IIIbFCGR3FCRIIIbGPI-anchored Fc-gamma receptor IIIbFCG3IGFR3

FCGR3B binds to the Fc region of IgG antibodies, particularly in the form of immune complexes. This binding facilitates the tethering of these complexes to the neutrophil surface, promoting phagocytosis and triggering intracellular signaling through cooperation with other membrane proteins like Mac-1 (CD11b/CD18), leading to the release of reactive oxygen species and proteolytic enzymes.