Spontaneous autoimmune thyroiditis in chickens. II. Evidence for autoresponsive thymocytes.

A major factor involved in the spontaneously occurring autoimmune thyroiditis of OS chickens is the presence of thyroid reactive cells in the thymus of young OS chicks. This was determined by transferring OS and normal strain thymocytes to T cell-depleted histocompatible normal chickens and examining the recipients for thyroiditis. Although both thymocyte populations reconstituted T cell function, only the OS thymocytes induced thyroiditis. Additional evidence for hyperactivity of the young OS thymus was provided by studying the in situ uptake of a radiolabeled thymidine analogue.