The influence of 7,12-dimethylbenzanthracene on natural killer (NK) cell function in rats.

The administration to 2 strains of rat (Alderley Park and Sprague Dawley) of 40 (2 X 20) mg of 7,12-dimethylbenzanthracene (DMBA) on a single day caused a transient depression of NK cell function. The splenic natural cytotoxic capacity of both DMBA treated and control animals was augmented by inclusion within the assay of interferon (IFN) but IFN failed to restore carcinogen-treated splenocyte cytotoxicity to normal values. Splenocyte populations from DMBA treated animals exhibiting reduced cytotoxic activity possessed normal frequencies of target-binding lymphocytes suggesting that the impairment of reactivity was attributable to a defect in the post-recognitive stage of NK mediated lysis. Administration of DMBA was not associated with a reduction in spleen weight or cellularity or with an impairment of splenic lymphocyte responsiveness to phytohaemagglutinin (PHA) indicating that depressed NK cell function was not a result of general lymphotoxicity. These data confirm previous reports that administration of chemical carcinogens may be associated with a depression of NK cell function.