CD16 (FcgammaRIII) is a 50-65 kDa glycoprotein serving as a low affinity IgG receptor. Unlike human, the murine protein is expressed only as a transmembrane isoform. Also CD32 (FcgammaRII) is a low affinity receptor for IgG, but its affinity is lower than that of CD16. These receptors are expressed on monocytes/macrophages, NK cells, granulocytes, mast cells, dendritic cells, and B cells. Their role is to mediate adaptive immune responses through binding the antibody-antigen immunocomplexes, but their effect on the particular cell differs according to the cell type.