Study on the Regulation of Thymic Hormone Secretion by Neural and Endocrine System-Using Primary Culture System of the Thymic Hormone-Secreting (Thymus Epthelial) Cells-

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(1) Separation of biologically active polypeptides (BAPs) from the culture supernatant of thymus epithelial cells (TEC).We tried to separate BAPs from the culture supernatant of TEC line, IT-45R1. The polypeptide fraction with 2.5kD in molecular weisht possessed the capacity to induce the responsiveness of rat thymic lymphocytes (TLs) against concanavalin A and phytohemagglutinin. By further separation using reversed-phase column, the former was found in the hydrophobic fraction and its target cells were enriched in lighter TLs, while the latter was detected in the hydrophilic fraction and its target was heavier TLs. About 80% of tat TLs bind to guinea pig erythrocytes and from rosettes (RFC), whereas other TLs (non-RFC) do not. The 3kD fraction possessed the capacity to endow non-RFC with resette forming activity. Furthermore, rosette formation-inducing activity was found in the two different fractions separated by reversed-phase column method. By the same methods described above, the … More activity to induce proliferation of TLs was recognized in 10kD fraction from the culture supernatant of TAD3, derived from lymphocyte dominant thymoma. It is assumed that the target cells for 10kD fraction bear CD4-8- phenotype, observed in the most immature TLs and that the adherent cells in thymus take, also, an role in the proliferation system.(2) Effects of neurotransmitter and hormone on the function of thymus epithelial cells.The effect of cholinergic agonists on TEC was examined by using TAD3. It is revealed that cholinergic agonists stimulate TEC to proliferate at preconfluent state. On the other hand, at confluent state, the agonists stimulate TEC to synthesize proteins. These activities were possibly induced by the signal through nicotinic acetylcholine receptor on TEC surface. Furthermore, the effect of growth hormone on TEC was examined. It is suggested that the hormone enhances the mitotic index of the TAD3 cells at preconfluent state and enhances the protein synthesis of IT-45R1 cells at confluent. Furthermore, growth hormone is detected to increase thymosin alpha 1 aynthesis of IT-45R1 cells at confluent state by using anti-synthetic thymosin alpha 1 antibody, prepared by us. Less