A<unk>  is a protein found on the surface of certain cells – including, among others, B lymphocytes, follicular dendritic cells, natural killer cells, macrophages, neutrophils, eosinophils, basophils, human platelets, and mast cells – that contribute to the protective functions of the immune system. Its name is derived from its binding specificity for a part of an antibody known as the<unk>  (fragment crystallizable) region.<unk> s bind to antibodies that are attached to infected cells or invading pathogens. Their activity stimulates phagocytic or cytotoxic cells to destroy microbes, or infected cells by antibody-mediated phagocytosis or antibody-dependent cell-mediated cytotoxicity. Some viruses such as flaviviruses use<unk> s to help them infect cells, by a mechanism known as antibody-dependent enhancement of infection.
Fc receptor
Thromboxane receptor
Co-receptor
Interleukin-3 receptor
IL-2 receptor
Type I cytokine receptor
Complement receptor 1
Interleukin-7 receptor