Maturational effects of thymic hormones on human helper and suppressor T cells: effects of FTS ('Facteur Thymique Sérique') and thymosin.

Human peripheral blood lymphocytes were isolated from healthy donors and pre-incubated with two thymic factors, FTS, a new synthetic polypeptide originally isolated and purified from serum, and thymosin Fraction V. After 24 hr of pre-incubation, the cells were washed and added to an allogeneic MLR and assayed for their ability to induce a suppressor or helper response. It was found that both factots were capable of inducing both helper and suppressor T cells and that the response was unpredictable. In both instances, more than 50% of the subjects studied responded with a helper effect. The addition of Con A augmented these effects. Since both helper and suppressor T cells can be induced by the factors studied herein, one must be aware of the potential effects on T-T and T-B balances of manipulation in clinical situations such as SLE or cellular immune deficiency states.