The effect of thymectomy on immunological tolerance to human serum albumin in chickens.

The effect of thymectomy performed on the day of hatching has been studied in chickens rendered tolerant by 100 mg of HSA injected also on the day of hatching. After challenge at the age of 6 and 9 weeks, no significant difference was observed between the group of tolerant chickens, in which the thymectomy was complete or incomplete, and the non-operated tolerant one. The delayed recovery from tolerance observed in mammals was not seen even in chickens in which thymus was removed completely and no thymic residue remained. The anti-HSA antibodies were even slightly higher in thymectomized birds than in the non-operated ones but the difference was statistically non-significant.