CD16/32 Antibody [93]

The lymphocyte Fcgamma receptors recognize the Fc portion of IgG, presented either as immune complexes or as free antibody. The different classes of receptors are distinct because of varying size, tissue distribution and affinity for IgGs. The Fc type II receptor is expressed on a wide variety of cells including B cells, hematopoietic cells, monocyte/macrophages, neutrophils, platelets, Langerhans cells, eosinophils, basophils, trophoblasts, and endothelial cells of the placenta. The Fcgamma type III receptors are higher affinity than the type II and are expressed on macrophages, NK cells and neutrophils. Both types of receptors can be expressed on the same cell and in varying ratios. The receptors are constitutively expressed, although cytokines and lymphokines can modulate their expression. Besides identifying FcgammaR+ cells, monoclonal antibodies to the FcgammaII/III receptor have been used to block Fc receptor binding of IgG, Fc-mediated signal transduction and effector functions, clearance of immune complexes and to attenuate infection by organisms dependent on FcgammaR for parasitic invasion. The monoclonal antibody 93 recognizes a conformational epitope formed by FcgammaII and FcgammaIII receptors.