Summary
A skin test to assess T-cell mediated delayed hypersensitivity (dh) and cutaneous basophil hypersensitivity (cbh) was evaluated in the interdigital skin of young chickens. Three-day-old chickens were sensitized with Mycobacterium tuberculosis, and the dh reaction was elicited in the interdigital skin in 10-, 17-, 24-, and 31-day-old chickens by intradermal injection of tuberculin. Cutaneous basophil hypersensitivity was elicited in the interdigital skin of 10- and 14-day-old chickens by a single intradermal injection of phytohemagglutinin-P (200 μg). The effect of immunosuppression on the results of interdigital skin test for dh and for cbh was evaluated in chickens that were treated with dexamethasone daily for 4 days before testing.
The dh reaction, as indicated by a significant (P < 0.01) increase in the mean interdigital skin thickness, was detectable in 10-day-old chickens and was consistently evident in 17-, 24-, and 31-day-old chickens. The dh response in the interdigital skin of 24-day-old chickens was comparable with that elicited in the standard wattle test. The cbh reaction, as indicted by a significant increase (P < 0.005) in skin thickness, was evident in the interdigital skin of 10- and 14-day-old chickens. Treatment with dexamethasone significantly decreased (P < 0.01) the dh and cbh reactions. Results of the study indicated that the interdigital skin test may be used to evaluate normal and suppressed cell-mediated dh and cbh reactions in chickens as young as 10 and 14 days old.