MODIFICATION OF TOLERANT STATE BY NEONATAL THYMECTOMY

Abstract

Immunological tolerance to sheep erythrocytes was induced by repeated antigenic challenge of rats which were thymectomized on the day of birth. Thoracic duct lymphocytes from these thymectomized tolerant rats failed to mount adoptive responses against sheep erythrocytes and interfered with the capacity of normal lymphocytes to mount such responses. In contrast with nonthymectomized tolerant rats, thymectomized animals responded well to sheep erythrocytes if challenge was accompanied by the injection of normal syngeneic lymphocytes. The cells that are lacking from tolerant rats as a consequence of neonatal thymectomy are probably identical with the radiosensitive cells that suppress normal lymphocytes transferred to intact tolerant rats.