Regulation of T lymphocyte differentiation and proliferation by thymus hormones, Ca2+ and chalone-T.
The regulatory effect on T lymphocyte proliferation of the differentiator thymosin hormone family (thymosin fr. 5, A. L. Goldstein), Ca2+, and purified inhibitory protein fractions prepared from calf thymus was investigated in C57Bl/6 mice. 1.2 mM Ca2+ concentration was the most favourable for murine thymocyte growth in culture. Net protein synthesis was transitorily inhibited by Cu2+ concentrations higher than 2 mM. This inhibition was followed by a marked inhibition of DNA synthesis 2 hrs later. The effect of thymosin fr. 5 was slight, of short duration, and oscillatory in nature; in contrast, chalone-T preparations inhibited thymocyte DNA synthesis permanently up to 12 hrs of cultivation. When spleen cells taken from mice treated with the immunoadjuvant Bacillus Calmette-Guérin (BCG) were exposed to chalone-T in culture, then stimulated with PHA, a reduced proliferative response was measured in chalone-T pretreated cultures compared to controls or spleen cells from normal non-BCG-activated mice. This result had led us to suggest that chalone-T has a dual effect on thymocytes, viz. it inhibits cell cycle progression and induces the phenotypic conversion of suppressor T lymphocytes. The multifactorial concept of T lymphocyte production is discussed.
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D050150:Chalones; D004247:DNA / Q000096:biosynthesis; D006131:Growth Inhibitors / Q000494:pharmacology*; D007700:Kinetics; D051379:Mice; D014176:Protein Biosynthesis; D011506:Proteins; D013601:T-Lymphocytes / Q000187:drug effects / Q000502:physiology*; D013947:Thymosin / Q000494:pharmacology*; D013951:Thymus Hormones / Q000494:pharmacology*
D050150:Chalones; D006131:Growth Inhibitors; D011506:Proteins; D013951:Thymus Hormones; C029299:chalone-T; D013947:Thymosin; D004247:DNA; D002118:Calcium