The effects of nickel on immune function in the rat

The immunotoxic potential of NiCl2 was evaluated in Fischer 344 rats following a single intramuscular injection at doses ranging from 10 to 20 mg/kg. Twenty-four hours following treatment, selected cellular and humoral immune function parameters were examined. Significant (P less than 0.05) decreases in body weights were observed in rats injected with 15 and 20 mg/kg NiCl2 as were decreases in spleen weights of rats receiving 20 mg/kg. The lymphoproliferative responses of splenocytes to the T cell mitogens concanavalin A (Con A), phytohemagglutinin (PHA), the T and B cell mitogen pokeweed mitogen (PWM) and the B cell mitogen Salmonella typhimurium mitogen (STM) were not significantly different from controls. No significant differences were observed between control and Ni-treated rats in the primary antibody response to sheep red blood cells (SRBC). On the other hand, natural killer (NK) cell activity was significantly (P less than 0.05) suppressed in rats injected with 10, 15, or 20 mg/kg NiCl2. NK cell suppression was observed in both male and female rats and for both allogeneic W/Fu-G1 target cells as well as xenogeneic YAC-1 target cells. Ni-induced suppression of NK activity was transient, with levels returning to control values within three days following treatment. Ni-induced suppression of NK activity was also manifested by an increase in mortality of rats injected with MADB106 tumor cells. These results extend to a second species our earlier findings that Ni suppresses NK activity.