Low affinity immunoglobulin gamma Fc region receptor III-B (CD16b)

The Low affinity immunoglobulin gamma Fc region receptor III-B (CD16b, encoded by the FCGR3B gene) is a cell surface glycoprotein expressed primarily on human polymorphonuclear neutrophils. It binds the constant region (Fc) portion of immunoglobulin G (IgG), exhibiting low affinity compared to other family members. Unlike its close homolog CD16a/FcγRIIIA—which mediates antibody-dependent cellular cytotoxicity—CD16b does not trigger phagocytosis or cytotoxic responses upon binding antibodies. Instead, it acts mainly as a "trap" for circulating immune complexes without activating downstream inflammatory signaling pathways in neutrophils. This unique function helps regulate peripheral immunity and prevent excessive tissue damage from inappropriate activation during normal clearance processes. Variations or deficiencies in FCGR3B have been linked to altered susceptibility to infection and autoimmunity; thus it represents both a biomarker candidate and potential therapeutic target within the broader context of inflammatory disease management.

Other names

Fc-gamma RIII-betaFcR-10IgG Fc receptor III-1CD16bFcgammaRIIIbFCGR3BLow affinity immunoglobulin gamma Fc region receptor III-B (official)Fc Fragment Of IgG, Low Affinity IIIb, Receptor (CD16b)IgG Fc Receptor III-b

For drugs targeting related pathways or using engineered antibodies with altered effector functions: Modulation of immune complex clearance. Potential reduction of inflammation by preventing inappropriate activation of neutrophils. Alteration of antibody effector functions through engineering to avoid binding to this low-affinity receptor.