The role of human chorionic gonadotropin and its peptide fragments in the regulation of IDO expression by human monocytes

The role of human chorionic gonadotropin (hCG) and its peptide fragments of β-subunit (LQGV, AQGV, VLPALP) in the regulation of indolеamine-2,3-dioxygenase (IDO) expression in human monocytes was studied in vitro. It is elucidated, that a high concentration of hCG (20 μg/ml) had an independent stimulatory eff ect on the expression of IDO in LPS -, and the IFN-γ – induced monocytes. Peptides AQGVand LQGV (20 μg/ml) also stimulated LPS-induced expression of IDO, but had no eff ect on IFN- γ-induced expression of the enzyme. At the same time, peptide VLPALP (20 μg/ml) provided the stimulatory eff ect only on the IFN-γ-induced expression of IDO. Simultaneously, peptides AQGV and VLPALP increased the production of IL-1β monocytes under LPS-stimulation, while hCG did not exert any independent eff ect. Generally, hCG and oligopeptides of β-hCG subunit enhance the expression of IDO by monocytes, which eventually contributes to peripheral immune tolerance development.