EN
Lindane, chlorphenvinphos, and carbaryl when administered to chickens in subtoxic doses for 90 days had no depressive effect on immune reactions expressed by haemagglutinin and haemolysin titres, the number of splenic. plaque-forming cells (PFC) and splenic lymphatic tissue reaction. In chickens treated with chlorphenvinphos the haemagglutinin titres and lymphatic tissue reaction were even increased as compared to controls. The possible reasons and mechanisms of immunostimulation observed in insecticide treated animals were discussed.