RECEPTORS FOR THE FC FRAGMENT OF IGG ON NATURAL-KILLER-CELLS

Natural killer (NK) cells are capable of binding to immune-complexed I gG via CD16-Fc(gamma)RIIIA molecules on their surface. This interactio n activates the NK cell lytic mechanism and induces production of lymp hokines by the activated cells. The exact molecular basis for CD16-med iated NK cell activation remains unclear; however, a number of recent studies have provided a framework for future research. It has been sho wn that CD16 perturbation on NK cells evokes a variety of early signal transduction events in these cells, such as polyphosphotidylinositol hydrolysis, [Ca2+]i increases and protein tyrosine kinase activation. Furthermore, the identification, of CD3-zeta/eta and/or Fc(epsilon)RI- gamma polypeptides complexed with CD16 in NK cells suggests a signal t ransduction mechanism analogous to those studied for the T cell recept or and Fc(epsilon)-receptor complexes. Therefore, research on each of these receptor complexes should now be viewed in light of a potential common signal transduction mechanism. Comparison of the similarities a nd differences observed should yield valuable insight into the complex network of molecular interactions apparently necessary for CD16-media ted NK cell activation.