Human CD16 as a lysis receptor mediating direct natural killer cell cytotoxicity.
In addition to their role in peptide antigen presentation, class I MHC proteins also play a critical role in inhibiting natural killer (NK) cytotoxicity through interaction with NK inhibitory receptors. Thus, NK cells are cytotoxic to virus-infected and tumor cells that have lost class I MHC protein expression. However, the nature of the receptors involved in the triggering of lysis of target cells is poorly understood. CD16 (Fcgamma receptor III) has been described as a receptor expressed on NK cells that facilitates antibody-dependent cellular cytotoxicity (ADCC) by binding to the Fc portion of various antibodies. However, we show here that CD16 has a broader function and is directly involved in the lysis of some virus-infected cells and tumor cells, independent of antibody binding. The presence of a putative CD16 ligand on appropriate target cells has also been demonstrated by the use of a CD16-Ig fusion protein.
D000911:Antibodies, Monoclonal / Q000276:immunology; D000920:Antibody-Dependent Cell Cytotoxicity; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000276:immunology; D007141:Immunoglobulin Fc Fragments / Q000276:immunology; D007136:Immunoglobulins / Q000235:genetics / Q000276:immunology; D007694:Killer Cells, Natural / Q000276:immunology*; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000276:immunology*; D017452:Receptors, IgG / Q000235:genetics / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology; D014407:Tumor Cells, Cultured