Fcreceptor

An Fc receptor is a protein found on the surface of certain immune cells that binds to the Fc portion of antibodies. Antibodies are proteins produced by the immune system that mark pathogens for destruction. The Fc portion is the tail end of the antibody molecule. By binding to antibodies, Fc receptors allow immune cells to target and eliminate antibody-coated pathogens or cells.

There are several types of Fc receptors, classified based on the type of antibody they bind to, such as Fcγ receptors for IgG antibodies, Fcε receptors for IgE antibodies, and Fcα receptors for IgA antibodies. These receptors are expressed on various immune cells, including phagocytes like macrophages and neutrophils, as well as natural killer cells, mast cells, and B cells.

When an Fc receptor binds to an antibody that is already attached to a target, it triggers a signal within the immune cell. This signaling can lead to a variety of responses, such as phagocytosis (engulfing and destroying the target), degranulation (releasing cytotoxic molecules), or the release of inflammatory mediators. Fc receptors play a crucial role in both innate and adaptive immunity, contributing to defense against infections and in allergic responses. They are also involved in antibody-dependent cell-mediated cytotoxicity (ADCC), where immune cells kill antibody-coated target cells.