Cellular and molecular interactions of thymus with endocrine organs and nervous system

T-cell ontogenesis has been disclosed to depend on the interactions of thym us with endocrine glands and nervous system as follows: i/ Thymic deprivati on not only impaired the immunological development but also brought about t he dysgenesis of pituitary anterior lobe. Conversely, hypophysectomy result ed in thymus atrophy with the disturbed immune responses, ii/ Binding of pi tuitary acidophilic cell hormones to their receptors on thymus epithelial c ells (TECs) augmented the release of thymic hormonal peptides (THPs) in vit ro. iii/ Elevation of blood glucocorticoid level after stress caused atroph y of thymus cortex through double positive thymocyte apoptosis. Morpho-mole cular alterations of cytoplasm preceded nuclear damage in the apoptotic thy mocytes. iv/ Administration of thymosin to the streptozotocin-induced diabe tic mice repressed mononuclear cell infiltration to the pancreatic islets. v/ Autonomic nerve fibers innervate thymic parenchyma. Binding of acetylcho lines (Achs) to Ach receptors on TECs enhanced protein synthetic activity w hich seemed to connect with THP production, vi/ Thymectomy not only depress ed the immune responses but also accelerated the reduction of learning and memory ability with aging. The operation appears to disturb the brain adren oceptor functions and to suppress the regulatory roles of hypothalamus to o ther nervous tissues. viii Several kinds of THPs, separated from the cultur e supernatant of TEC line by high performance liquid chromatography, showed a favorable effect on the thymocytes at different stage of differentiation and maturation. viii/ Thymosin, thymulin and THPs were capable of prolifer ating and differentiating thymocytes in vitro. However, the administration of each thymic product to the thymus-deprived animals could not restore fro m their "wasting disease". Since TECs are composed of a heterogeneous popul ation, it would be one of essential ways for isolating "true thymus hormone " (TTH) to use the material which consists of functionally homogeneous subs et of TECs. ix/ An additional grafting of pituitary gland to the thymus-gra fted nude mice improved the disturbed T-cell ontogeny. Accordingly, the adm inistration of "TTH" and pituitary acidophilic cell hormones might be more hopeful procedure for rescuing the thymus-deprived animals from "wasting di sease".