Monoclonal antibodies directed against HLA molecules affect the lytic and proliferative behavior of a cloned line of human natural killer cells.

Monoclonal antibodies with specificity for HLA class I and class II antigens were generated against a cloned line of human natural killer cells (NK 3.3). These antibodies were selected for their ability to either inhibit or enhance the lytic activity of NK 3.3. Antibody pretreatment and binding studies have established that the antibodies act at the level of the killer cell; we show in this paper that the nature of the target cell also plays a role in whether the antibody causes enhancement or inhibition of lysis. We provide evidence that these antibodies act at an early stage of lysis prior to the Ca++ dependent programming for lysis step, and describe the effects of these antibodies on the proliferation of cloned and uncloned lines of natural killer cells.