Self recognition in allogeneic thymic chimeras. Self recognition by T helper cells from thymus-engrafted nude mice is restricted to the thymic H-2 haplotype.

To examine the possibility that the thymus determines the I region-restricted self-recognition repertoire expressed by T helper (TH) cells, thymic chimeras were constructed by transplanting allogeneic neonatal thymic lobes into congenitally athymic nude mice. Spleen TH cells from the thymic chimeras were themselves of nude host origin but only cooperated with B+ accessory cells of the thymic haplotype for primary in vitro responses to sheep erythrocytes and trinitrophenyl conjugate of keyhole limpet hemocyanin. Thus, these experiments demonstrate that the self-recognition repertoire expressed by TH cells is determined by the H-2 phenotype of the intrathymic environment in which the TH cells had differentiated.