CD16b; low affinity immunoglobulin gamma Fc region receptor III-B; IgG Fc receptor III-1; Fc-gamma RIII-beta; Fc-gamma RIIIb; FcRIIIb; Fc-gamma RIII; FcRIII; FcR-10 (FCGR3B CD16B FCG3 FCGR3 IGFR3)

Function

• low affinity receptor for the Fc region of IgG
• binds complexed or aggregated IgG & also monomeric IgG
• contrary to CD16a, is not able to mediate antibody-dependent cytotoxicity & phagocytosis
• may serve as a trap for immune complexes in the peripheral circulation not activating neutrophils
• interacts with INPP5D/SHIP1 (putative)

Structure

• monomer
• glycosylated; glycosylation plays an inhibitory role in the interaction with IgG3
• soluble form is produced by a proteolytic cleavage
• contains 2 Ig-like C2-type domains (immunoglobulin-like)

Compartment

• cell membrane; lipid-anchor, GPI-anchor
• secreted, after cleavage

Expression

• expressed specifically by neutrophils
• also expressed by stimulated eosinophils

Pathology

• more active FCGR3B*01 allele has been associated with severe renal disease in some systemic vasculitides

Genetics

• encoded by one of two nearly indentical genes: FCGR3A & FCGR3B with tissue-specific expression:
• Phe-203 in FCGR3A determines the transmembrane domains
• Ser-203 in FCGR3B determines the GPI-anchoring

Polymorphism

• 3 allelic forms of FCGR3B:
  • FCGR3B*01 (NA-1)
  • FCGR3B*02 (HNA-1b, NA-2)
  • SH
• FCGR3B*01 & FCGR3B*02 are detectable with antibodies against the biallelic neutrophil-specific antigen system NA

More general terms

• CD16, Fc gamma receptor III or Fc gamma receptor (low affinity)
• glypiated protein

Database

• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:2215
• OMIM: https://mirror.omim.org/entry/610665
• UniProt: http://www.uniprot.org/uniprot/O75015.html