CD16 is a cluster of differentiation molecule found on the surface of natural killer (NK) cells, monocytes and macrophages. It can be used to isolate populations of NK cells by antibodies directed towards CD16, using fluorescent-activated cell sorting or magnetic-activated cell sorting. CD16 has been identified as Fc receptors FcγRIIIa (CD16a) and FcγRIIIb (CD16b). The two isoforms of the CD16a stimulatory receptor found on NK cells and macrophages differ by one amino acid at codon 158 (V/F) and are important for antibody-dependent cell-mediated cytotoxicity (ADCC). The high affinity 158 V/V homodimer of CD16A is present on approximately 20% of the population and the lower affinity F/F homodimer and F/V heterodimer are present in the remaining 80%.