Effects of aflatoxin B1 on murine lymphocytic functions

We recently reported on the immunotoxic effects of Aflatoxin B1 (AFB1), a secondary fungal metabolite of Aspergillus flavus in mice. The present paper describes the effect of AFB1 on cellular functions in lymphocytes after in vivo or in vitro exposures. Male BALB/c mice received 0, 0.03, 0.145 or 0.7 mg/kg body weight of AFB1 for 4 weeks. A dose-related decrease in DNA synthesis in lymphocyte cultures with or without the mitogens (lipopolysaccharide, phytohemagglutinin, pokeweed mitogen and concanavalin A) was observed. No effects on protein or ribonucleic acid synthesis were observed. There were dose-dependent decreases in peripheral leucocyte counts and natural killer cell function. Splenic lymphocytes from normal mice cultured with 10(-6) to 10(-4) M AFB1 had decreased DNA synthesis at greater than 1 X 10(-5) M, a decreased protein synthesis at 10(-4) M and decreased RNA synthesis at greater than 2.5 X 10(-5) M. In vitro addition of AFB1 (greater than 50 microM) reduced generation of concanavalin A-induced suppressor cells. The results suggest that AFB1 had a direct and complex effect on lymphocytes and there is a differential sensitivity of various subpopulations.