Description
FcRII (CD32) is a low affinity receptor for IgG that binds only IgG immune complexes and is expressed on a diverse range of cells such as monocytes, macrophages, neutrophils, eosinophils, platelets, and B cells. There are three main classes of human leucocyte IgG Fc receptor (FcR) : FcRI (CD64), FcRII (CD32), and FcR (CD16) which are distinguished on the basis of molecular weights, cellular distribution, affinity/specificity for ligand and by reactivity with monoclonal antibodies. Many important functions have been attributed to these receptors and they are regarded as providing an essential link between cellular and humoral immune systems. The most ubiquitous of these receptors is FcRII. The extracellular region of FcRII comprises two C2-type Ig-like disulfide-bonded domains which is structurally conserved in all of the Ig superfamily leukocyte FcRs (and represents an Ig-interactive motif. FcRII is involved in a number of immune responses including antibody-dependent cell-mediated cytotoxicity, clearance of immune complexes, release of inflammatory mediators, and regulation of antibody production