The 3G8 monoclonal antibody specifically reacts with human CD16, the low affinity IgG receptor III (FC gamma RIII). CD16 is expressed on granulocytes, monocytes, macrophages, and NK cells and plays a role in NK activation and signal transduction. CD16 is expressed as either CD16a or CD16b. CD16a is a polypeptide-anchored transmembrane protein and CD16b is a glycosylphosphatidylinositol (GPI)-anchored protein that is expressed exclusively on neutrophils.