Activation and phenotyping of LAK generated by exposure to product of cells transformed by interleukin 2 cDNA.

It has been previously found that local administration of X63-m-IL-2 cells transformed by interleukin 2 (IL-2) cDNA and constitutively producing large quantities of IL-2 mediated regressions of murine plasmacytomas and 3-methyl-cholanthrene-induced sarcomas transplanted in syngeneic mice. Here we show that killer cells generated by cultivation of spleen cells in supernatants from X63-m-IL-2 cultures (LAK) or by co-cultivation of murine splenocytes with X63-m-IL-2 cells were cytolytic for natural killer (NK)-sensitive as well as NK-resistant target cells, including the IL-2-producing X63-m-IL-2 cells. Spleen cells cultured in X63-m-IL-2 supernatants or co-cultivated with X63-m-IL-2 cells yielded predominantly Thy 1.2+, CD3+, LFA-1+ lymphocytes. The in vitro results suggest that the LAK cells generated due to the IL-2 production by genetically engineered cells probably help to terminate the treatment by killing the IL-2 producers.