Regulation of in vitro generation of cell-mediated cytotoxicity. II. Characterization of thymosin-induced suppressor T cells.
Thymosin fraction 5 can induce the appearance of suppressor T cells capable of regulating the in vitro generation of cytotoxic T lymphocytes (CTL) in a 5-day allogeneic or syngeneic mixed lymphocyte-tumor culture (MLTC). Characterization of the suppressor cell population demonstrated it to be a nonadherent, cyclophosphamide-sensitive T cell. In addition, adult thymectomy (Tx) eliminated suppressor cell precursors in spleen, pointing to a direct thymic dependence of the population. Kinetic studies showed that the thymosin influence was necessary for at least the first 12 hr of culture in order for optimal suppression to occur. The in vitro-generated suppressor T cells were antigen specific and could be generated with spleen, thymus, or lymph node cell preparations, suggesting the widespread existence of a regulatory T-cell population under direct humoral thymic control.
D000818:Animals; D000918:Antibody Specificity; D003520:Cyclophosphamide / Q000494:pharmacology; D007104:Immune Adherence Reaction; D007700:Kinetics; D008297:Male; D051379:Mice; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects*; D013934:Thymectomy; D013947:Thymosin / Q000494:pharmacology*; D013951:Thymus Hormones / Q000494:pharmacology*
D013951:Thymus Hormones; D013947:Thymosin; D003520:Cyclophosphamide