Studies of immune function of CD-1 mice exposed to aflatoxin B1.

The immunotoxic potential of aflatoxin B1 (AFB1), a secondary metabolite of Aspergillus flavus and a known animal hepatocarcinogen, was evaluated in CD-1 mice. Male mice received 0, 0.03, 0.145 or 0.70 mg/kg of AFB1 orally every other day for 2 weeks in a corn oil:ethanol vehicle. Splenic lymphocytes were cultured in the presence of lipopolysaccharide (LPS), phytohemagglutinin (PHA), or pokeweed mitogen (PWM). A dose-related inhibition of [3H]thymidine uptake in lymphocyte cultures, with or without the above mitogens, was observed after 2 weeks of AFB1 exposure. Synthesis of DNA was decreased in mixed lymphocyte cultures. Primary antibody production by splenic cells, from animals challenged with a T-dependent antigen (sheep red blood cells), was affected by AFB1. No effects were observed, however, when animals were challenged with a T-independent antigen (LPS). A dose-related suppression of a delayed-type hypersensitivity reaction to keyhole limpet hemocyanin was observed. The results suggested that AFB1 was immunotoxic in CD-1 mice.