抗體恆定區接受器(Fc receptor)

Fc受體是某些細胞的表面上發現的一種蛋白質 - 包括B細胞(B cell)、濾泡狀樹突細胞(Follicular dendritic cells)、自然殺手細胞(Nature killer cell)、巨噬細胞(Macrophage)、嗜中性球(neutrophil)、嗜酸性球(eosinophil)、嗜鹼性球(basophil)和肥大細胞(Mast cell) - 這有助於免疫功能的維持

Receptor name	Principal antibody ligand	Affinity for ligand	Cell distribution	Effect following binding to antibody
FcγRI (CD64)	IgG1 and IgG3	High (Kd ~ 10⁻⁹ M)	巨噬細胞(Macrophage) 嗜中性球(neutrophil) 嗜酸性球(eosinophil) 樹突細胞(Dendritic Cells)	Phagocytosis Cell activation Activation of respiratory burst Induction of microbe killing
FcγRIIA (CD32)	IgG	Low (Kd > 10⁻⁷ M)	巨噬細胞(Macrophage) 嗜中性球(neutrophil) 嗜酸性球(eosinophil) Platelets Langerhans cells	Phagocytosis Degranulation (eosinophils)
FcγRIIB1 (CD32)	IgG	Low (Kd > 10⁻⁷ M)	B細胞(B cell) 肥大細胞(Mast cell)	No phagocytosis Inhibition of cell activity
FcγRIIB2 (CD32)	IgG	Low (Kd > 10⁻⁷ M)	巨噬細胞(Macrophage) 嗜中性球(neutrophil) 嗜酸性球(eosinophil)	Phagocytosis Inhibition of cell activity
FcγRIIIA (CD16a)	IgG	Low (Kd > 10⁻⁶ M)	NK cells 巨噬細胞(Macrophage) (certain tissues)	Induction of 抗體依賴型細胞介導的細胞毒性作用(antibody-dependent cell-mediated cytotoxicity, ADCC) Induction of cytokine release by macrophages
FcγRIIIB (CD16b)	IgG	Low (Kd > 10⁻⁶ M)	嗜酸性球(eosinophil) 巨噬細胞(Macrophage) 嗜中性球(neutrophil) 肥大細胞(Mast cell) Follicular dendritic cells	Induction of microbe killing
FcεRI	IgE	High (Kd ~ 10⁻¹⁰ M)	肥大細胞(Mast cell) 嗜酸性球(eosinophil) 嗜鹼性球(basophil) Langerhans cells	Degranulation
FcεRII (CD23)	IgE	Low (Kd > 10⁻⁷ M)	B細胞(B cell) 嗜酸性球(eosinophil) Langerhans cells	Possible adhesion molecule
FcαRI (CD89)	IgA	Low (Kd > 10⁻⁶ M)	Monocytes 巨噬細胞(Macrophage) 嗜中性球(neutrophil) 嗜酸性球(eosinophil)	Phagocytosis Induction of microbe killing
Fcα/μR	IgA and IgM	High for IgM, Mid for IgA	B細胞(B cell) Mesangial cells 巨噬細胞(Macrophage)	Endocytosis Induction of microbe killing
FcRn	IgG		單核球(Monocyte) 巨噬細胞(Macrophage) 樹突細胞(Dendritic Cells) Epithelial cells Endothelial cells Hepatocytes	Transfers IgG from a mother to fetus through the placenta Transfers IgG from a mother to infant in milk Protects IgG from degradation