Cytotoxic activity of various LAK cells against autologous lung cancer, K-562 and Daudi cells.

Comparative cytotoxic activity and specificity studies of lymphokine activated killer (LAK) cells from different sources and preparations were carried out. Cytotoxic studies of lymphocytes from regional lymph nodes (Rn-LAK), peripheral blood (Pb-LAK) and those stimulated by autologous tumor cells and then activated by recombinant interleukine 2 (St-LAK) against autologous lung cancer cells, were conducted using the 51Cr-releasing test. The cytotoxic activities of these three LAK cells against autologous fibroblasts, allogeneic tumor cells, K-562 and Daudi cells were also compared. A time course experiment disclosed that the cytotoxic activity of Pb-LAK cells against autologous tumor cells reached a maximum on day 3 and declined shortly after the peak while that of Rn-LAK cells gradually increased to a maximum on day 7 and remained at a high titer for at least two weeks. The cytotoxic activity of Rn-LAK cells was significantly higher than that of Pb-LAK cells in seven out of 10 individual experiments and that of stimulated LAK (St-LAK) cells was higher than the cytotoxic activities of the other LAK cells in eight out of nine experiments. A specificity study showed that Rn-LAK cells possessed a higher cytotoxic activity against autologous tumor cells and a lower cytotoxic activity against autologous fibroblasts and allogeneic tumor cells than Pb-LAK cells. A comparative study of cytotoxic activities against K-562, Daudi cells and autologous tumor cells between St- and Rn-LAK cells demonstrated that although there was no difference in natural killer activity, cytotoxic activity against autologous tumor cells as well as the LAK activity of St-LAK cells were higher than that of Rn-LAK cells. These results indicate that the activities and specificities of LAK cells differ according to their source and preparation.