FCGR2A

FCGR2A, also known as CD32, is a protein encoded by the FCGR2A gene. It is a low-affinity receptor for the Fc portion of immunoglobulin G (IgG). FCGR2A is a transmembrane protein that plays a crucial role in the immune system, particularly in innate immunity and antibody-dependent cellular cytotoxicity (ADCC). It is expressed on a variety of immune cells, including neutrophils, monocytes, macrophages, and some B cells.

The primary function of FCGR2A is to bind to IgG antibodies that have already attached to target cells or pathogens. This binding can trigger several downstream cellular responses. For example, when FCGR2A on phagocytic cells binds to IgG-opsonized particles, it promotes phagocytosis, the engulfment and destruction of the foreign material. Furthermore, FCGR2A can activate immune cells to release inflammatory mediators and cytotoxic molecules, contributing to the elimination of infected or cancerous cells through ADCC.

Variations in the FCGR2A gene have been associated with differences in immune responses and susceptibility to certain diseases. These genetic polymorphisms can affect the expression levels or binding affinity of the FCGR2A protein, influencing how effectively individuals mount immune responses against pathogens or respond to therapeutic antibodies. Research into FCGR2A continues to explore its involvement in autoimmune diseases, infectious diseases, and cancer immunotherapy.