Brain-associated thymic antigen in chickens.

Sera were produced in rabbits against a saline extract of chicken embryo brain (CBE). The rabbit anti-chicken brain (RACB) sera revealed, in micro-Ouchterlony studies, brain-associated antigens in extracts from the thymus, bursa, spleen and kidney. Absorption of the sera with normal serum (ns) and kidney (K), (RACBns, K), removed all reactivity with tissues other than brain. However, cytotoxic studies demonstrated that the kidney-absorbed serum was toxic to lymphocytes from thymus, bursa and spleen. Proper dilution of the RACBns, K produced a serum which was more cytotoxic for thymic lymphocytes than bursal lymphocytes. This study indicates the presence of brain-associated thymic antigens in the chicken.