Influence of the thymus-corticothropin-growth hormone interaction on the rejection of skin allografts in the rat.

Skin allograft rejection was noticeably delayed in rats following hypophysectomy. Daily injections of hypophyseal growth hormone restored the normal reaction. Additional thymectomy had no influence on the rejection of hypophysectomized rats. In these animals growth hormone by itself had no significant influence on the graft rejection. It only restored a normal reaction when given together with thymic hormone. Corticotropin injections accelerated the allograft rejection. On this action of corticotropin thymic hormone has shown a significant inhibitory influence. The thymus was thus proved to be a synergist to growth hormone and an antagonist to corticotropin. Previous observations made with usual endocrinological test- are thus confirmed with an immunological test.