The action of calcium antagonists in the human natural killer cell-mediated cytotoxicity.

The Ca2+-channel blocker Nifedipine and the Calmodulin inhibitor Prothazin suppressed the human NK-mediated cytolysis. Both drugs exerted the same dose-dependent effect. The inhibition was partially reversible after withdrawing of the Ca2+-antagonists. There exists evidence that neither effector-target cell binding, nor effector cell function, but the initiation of the target cell lysis was affected by these inhibitors. Hence, the Ca2+-requirement of the NK cytotoxic reaction seems to be due to an essential Ca2+-influx into the target cell.