Effect of two Thymosin Fraction 5 Polypeptides on Human Peripheral Blood Lymphocytes

Abstract

Thymosin fraction 5 polypeptides β4 and αl were tested for their ability to affect certain immunological parameters of human peripheral blood lymphocytes (PBL). PBL were cultured with various concentrations of the peptides for 24 hours.

Thymosin β4 was found to induce a significant decrease in the expression of the Fc receptors of PBL, as well as in their ability to express antibody dependent cellular cytotoxic (ADCC) activity. In addition, this peptide had the ability to increase the percentage of T4 lymphocytes in normal and immunosuppressed donors and to decrease the percentage of T8 positive cells in normal donors. Finally, β4 peptide caused a small increase in the capacity of peripheral blood lymphocytes to form sheep red blood cell (SRBC) rosettes (E_R). In parallel experiments thymosin αl was found inactive. The results presented here indicate that thymosin β4 may be used as an immunoregulatory molecule in patients with immunodeficiencies.