Thymosin: an immunomodulator of antibody production in man.

Thymosin (TFX) stimulates polyclonal antibody synthesis of human peripheral blood, lymph node and spleen lymphocytes. This stimulation is observed only with T-cell-dependent polyclonal activators of immunoglobulin production and its mechanism appears to be associated with TFX-induced activation of T-helper cells. On the other hand, antibody production in vitro of lymphocytes already involved in high humoral responses is inhibited by thymosin. TFX has similar activity both in vitro and in vivo.