Experimental Study Of Selected Modification Of NK Cells Function By Blockade Of Killer-cells Inhibitory Receptors

Natural killer (NK) cells, which are non-specificity immunity cells, have the ability to kill some virus and tumor cells, and not to host normal cells. This suggest that NK cells can recognize host normal tissues. NK cells express two different receptors.-killer cells activating receptors (KARs) and killer cells inhibitory receptors (KIRs), both of which determine cytotoxic activity. KIRs play an dominant role in regulating cytotoxic activity.Objective: This subject discusses the regulation mechanism of the cytotoxic activity of NK by means of the histocompatibility of KIRs and their ligands and the killing effects of NK cells against tumor cells with KIRs blockade.Methods: The KIRs of NK cells were blockaded by the monoclonal antibody CD158a and CD158b. The NK cells, which are blockaded by monoclonal antibody CD158a, CD158b, are cocultured with K562(susceptible to NK cells) or Raji (insusceptible to NK cells) at different E/T ratios in vitro. The E/T ratios were 5: 1, 10: 1 and 20: 1. The cytotoxic activity of NK-92MI against cancer cells in different E/T ratios are examined with flow cytometry.Results: The best cytotoxicity appears in 4-hour coculture. The killing effects is enhanced by the elevation of E/T ratios. The cytotoxic activity of NK-92MI treated by CD158 were significantly higher than untreated cells (P<0.05). The cytotoxic activity of NK-92MI with KIRs selected blockade is enhanced by 7%-8%.Conclusions: The cytotoxic effects of KIRs blockade NK-92MI against tumor cells were significantly enhanced in comparison with that of untreated cells.