In vivo hemopoietic activity of thymic extract 'Thymustimulin' in aged healthy humans.

The in vivo effects of the administration of Thymustimulin (TST), a bovine thymic extract, on the hemopoiesis of healthy elderly subjects were evaluated. Five healthy individuals over 70 years of age were treated with TST for one month. Before and at the end of TST treatment, peripheral blood cell counts were performed and the in vitro growth of peripheral blood erythroid (BFU-E) and granulocyte-macrophage (CFU-GM) progenitor cells was assessed, together with the determination of T-lymphocyte subpopulations. Our results indicate that in elderly subjects, TST significantly (p less than 0.05) enhances the number of BFU-E; furthermore, a slight increase in the hemoglobin levels was observed. BFU-E positively correlated with CD3+ T-lymphocytes (r = 0.84; p less than 0.02), which significantly (p less than 0.01) increased after TST administration. No differences were found after TST treatment in the other parameters considered. TST seems able to exert a stimulatory effect on the erythropoiesis of elderly subjects, probably by its effects on T-lymphocyte functions.