Immunotoxicological investigation of the effects of a pesticide; cypermethrin.

The effects of a synthetic pyrethroid pesticide cypermethrin on the immune system were studied. The effect of a daily oral administration of 1/40, 1/20 and 1/10 of LD50 was studied in rabbits for its influence on the humoral immune response after vaccination with Salmonella typhi, as well as on cell-mediated immunity. The two higher doses induced a significant dose-dependent decrease of serum antibody titers. The skin redness measured in the tuberculin skin test showed the same dose-dependent tendency. In subacute experiments with rats, a significant dose-dependent decrease was observed both in the anti-ovalbumin titer of blood sera measured in passive hemagglutination test and in the autologous rosette-formation of T-lymphocytes in groups fed the higher doses.