FCGR3A

FCGR3A, also known as CD16a, is a low-affinity receptor for the Fc portion of immunoglobulin G (IgG). It is primarily expressed on the surface of natural killer (NK) cells and also on macrophages, neutrophils, and eosinophils. This receptor plays a crucial role in antibody-dependent cell-mediated cytotoxicity (ADCC), a process where immune cells kill target cells that have been coated with antibodies.

When an antibody binds to a target cell, the Fc portion of the antibody can be recognized by FCGR3A on an immune effector cell. This binding triggers the activation of the effector cell, leading to the release of cytotoxic molecules that induce apoptosis (programmed cell death) in the target cell. This mechanism is vital for eliminating virus-infected cells and tumor cells.

The gene encoding FCGR3A is located on chromosome 1q23.3 and is subject to genetic polymorphisms, which can influence the binding affinity of the receptor and consequently affect immune responses. For example, certain FCGR3A variants have been associated with increased susceptibility to autoimmune diseases or variations in response to therapeutic antibodies. Research into FCGR3A and its polymorphisms is ongoing, particularly in the context of immunotherapy and the development of novel treatments for cancer and infectious diseases.