[Cytotoxic action of natural killer cells on human tumor cells]

Natural killer cell cytotoxicity was studied in a 18-hour 51Cr-release assay in the cultures of human tumor target cells: K562 leukemia and lung adenocarcinoma (LAC) cells. The mean cytotoxic value was similar for K562 and LAC cells: 36.13 +/- 3.23% and 40.78 +/- 3.43%, respectively, although significant individual variability was recorded. The similar cytolytic action of blood mononuclear cells (MNC) on the two tumor lines was observed in 30% of normal donors. MNC from 30% donors produced more pronounced lytic action on K562 cells while MNC from other 30% donors lysed mainly LAC cells. In the competitive inhibition test cold K562 cells more effectively than cold LAC cells suppressed the MNC-induced lysis of both K562 and LAC cells.