[Thymosin fraction 5. Preclinical study]

Thymosin fraction 5 from the Research Institute for Pharmacy and Biochemistry possessed the immunomodulatory activity in performed tests. The activity is manifested mostly by the induction of the maturation and the differentiation of T cell precursors, which are released from thymus to secondary lymphoid organs. Thymosin fraction 5 causes the expression of the surface membrane markers Thy-1.2, Lyt-2 and L3T4 on the immature T lymphocytes as well. The induced cells are immunocompetent and able to exert the complete functional activity. In the intact mice thymosin fraction 5 had not pronounced effect on the functional potency of mature immunocompetent cells, but in MTA influenced mice its stimulatory effect on the proliferative response to mitogens and on the antibody production against the T-dependent antigen was demonstrated. Thymosin fraction 5 influenced positively not only the components of the specific immunity, but also the functional activity of peritoneal macrophages. The toxicity of thymosin fraction 5 was in the battery of tests in vitro and in vivo very low and therefore it can be considered to be harmless for the clinical practice.