Enhancement of murine lymphoma cell lysability by CTL and by LAK cells, after treatments with mitomycin C and with adriamycin.

Murine lymphoma cells (RDM4) were treated, in culture, with adriamycin (ADM) and with mitomycin C (Mit C) at various concentrations for 20 h. They were then used as 51Cr-labelled target cells and tested for their sensitivity to the killing action both of specifically allosensitized cytotoxic T lymphocytes (CTL) and of lymphokine-activated killer (LAK) cells. They were also used as "cold target" inhibitors, in cytotoxicity assays involving CTL or LAK and 51Cr-labelled target cells. The results showed that treatments with different concentrations of Mit C enhanced the sensitivity of RDM4 cells to the killing actions of both CTL and LAK cells. ADM slightly enhanced sensitivity to the killing action by CTL, but to a much lesser extent than Mit C did. However, ADM proved to be almost as efficient as Mit C in its sensitizing action, in the case of lysis by LAK cells. Treatments with both drugs did not seem to modify the capacity of RDM4 cells to act as "cold target competitors" in cytotoxicity assays involving CTL killers, but did so in experiments involving the lytic action exerted by LAK cells.