Synthetic peptide, a fragment of the β-subunit of chorionic gonadotropin, inhibits mitogen-stimulated proliferation of human lymphocytesin vitro

Abstract

Similar to chorionic gonadotropin, synthetic fragment of the 13-subunit of chorionic gonadotropin (128th-145th amino acid), inhibits mitogen-stimulated proliferation of human lymphocytes in vitro and binds to membrane receptors of human peripheral blood monocytes. Key Words: chorionic gonadotropin; peptide; lymphocytes; proliferation, inhibitionHuman chorionic gonadotropin (HCG), a gonadotropic glycoprotein, is a protein factor emerging in pregnancy [9]. It was reported that HCG not only fulfils the luteinizing function and stimulates production of steroid hormones but also possesses immunomodulating activity. However, there is controzversy over the effect of HCG on immunocompetent cells [6,10], and the mechanisms of HCG action are unclear.Since the C-terminal sequence of HCG [3-subunit is unique for this hormone [2] it seems reasonable to study the contribution of this fragment to biological activity of HCG. Previously, it was shown that this fragment is not necessary for the interaction between HCG and the gonad cell receptors, intracellular cAMP increase, and induction of steroid hormone synthesis in vitro [7]. However, the significance of this fragment for immunomodulating activity of HCG is unclear.The aim of the present study was to examine the in vitro effects of synthetic fragment of the C-terminal sequence of HCG 13-subunit (128th-145th amino