The clone 3G8, a mouse monoclonal antibody, binds to the 50-65 kDa transmembrane protein of IgG Fc?RIII known as CD16, a surface antigen commonly associated with human NK cells. In addition to surface expression on NK cells, CD16 is expressed on activated monocytes, macrophages, neutrophils, and placental trophoblasts in humans. 3G8 binds either with the aggregated IgG or IgG-antigen complex which functions in NK cell activation, phagocytosis, and antibody-dependent cell-mediated cytotoxicity (ADCC).