Delayed type hypersensitivity reaction as indicator of cellular immune competence in broiler chickens exposed to dietary corticosterone

Three experiments were performed to evaluate the delayed type hypersensitivity test against keyhole limpet haemocyanin as a parameter to measure stress-induced cellular immune suppression. The test was optimised for broiler chickens and evaluated in a stress model in which plasma corticosterone levels were increased by the administration of 0.5 or 2 mg corticosterone/chicken/day. Keyhole limpet haemocyanin evoked a hypersensitivity type IV response, which was sensitive to increased plasma corticosterone levels. However, the inhibitory effect of 0.5 mg corticosterone/chicken/day was not significantly different from the solvent control (ethanol), because of an inhibitory effect of ethanol itself. The inhibitory effect of 2 mg corticosterone/chicken/day was mainly due to an effect on female chickens, indicating a difference in corticosterone sensitivity between gender. Our data indicate that the delayed type hypersensitivity test against keyhole limpet haemocyanin was sensitive for increased plasma corticosterone concentrations. Therefore this may be an easy and useful test for measuring cell-mediated immunity in corticosterone related immune-suppressed broiler chickens