Immunomodulating activity of pidotimod.

Experiments were performed to analyze the effect of the immunomodulating agent pidotimod ((R)-3-[(S)-(5-oxo-2-pyrrolidinyl) carbonyl]-thiazolidine-4-carboxylic acid, PGT/1A, CAS 121808-62-6) on the mouse splenic proliferative response to Con-A and IL-2, natural killer (NK) cell activity and thymocyte apoptosis. The results indicate that in vivo treatment with pidotimod (200 mg/kg i.p. for 5 days) causes a significant increase in the proliferative response to mitogens (including Con-A and IL-2) and the cytotoxic activity mediated by NK cells. Pidotimod inhibits in vitro thymocyte apoptosis caused by other inducing agents such as protein kinase C activator 12-O-tetradecanoyl-phorbol-13-acetate, Ca(++)-ionophore A23187, genistein and interleukin-2 (IL-2).