Dietary indole-3-carbinol alters immune functions in rats

To further elucidate the physiological mechanisms that may contribute to th e dichotomy of effect of indole-3-carbinol (13C) on cancer development, we examined immune functions representative of the three major branches of the immune system in rats fed either a high (150 mg/kg) or low (50 mg/kg) dose of 13C. Animals fed the high dose of 13C daily for 7 wk had significantly reduced natural killer cell activity. In contrast T-cell-mediated delayed-t ype hypersensitivity was significantly elevated. Antibody production in res ponse to the antigen keyhole limper hemocyanin war not significantly altere d compared to controls. These results indicate that exposure to 13C may hav e differential effects on major immune responses. The significance of these immune function alter aliens in tumor development will require additional investigation of the effects of dietary 13C on immune functions in appropri ate tumor models.