Effects of melatonin on Th1/Th2 balance in thymus cell cultures in rat

EFFECTS OF MELATONİN ON Th1/Th2 BALANCE IN THYMUS CELL CULTURES IN RATZafer ŞAHİNABSTRACTA reciprocal relationship between the pineal gland, the main source of melatonin (MT) and the immune system has beensuggested. It has been reported that MT has immunomodulatory actions in different animal species; however, effects of MT andits main source (the pineal gland) on thymocytes and its cytokine secretion profiles are not well-understood. Therefore, weaimed to investigate the effects of MT on the T helper 1 (Th1) and T helper 2 (Th2) lymphocyte balance in thymocyte culturesprepared from pinealectomized (Pnx) and non-Pnx rats consisting of intact and sham-operated control rats.The experiments were performed in 10 µg/ml concanavalin A (Con A) stimulated and nonstimulated thymocytes fordetermination of cytokine production profiles. Interferon-gamma (IFN-γ) (produced by Th1 cells), interleukin (IL)-4 and IL-10(produced by Th2 cells) concentrations were measured in the supernatants at 0 and 24 h after treatment with two differentconcentrations of MT (10 and 100 µM). IFN-γ levels increased significantly at 24 h in both Con A stimulated andnon-stimulated media prepared from Pnx rats. In contrast, IL-10 levels were sigificantly reduced at 24 h in the culturesbelonging to Pnx rats with and without Con A. While 100 µM concentration of MT adversed the effects of Pnx on IFN-γ andIL-10 levels, the 10 µM dose of MT had no effect. There was no significant differences between the control and MT treatedgroups in terms of IFN-γ and IL-10 levels.Our results show that the cytokine production profile was significantly shifted towards Th1 by Pnx and implicate that 100µM dose of MT treatment can decrease IFN-γ and increase IL-10, which is regarded as a sign of Th2 dominance. This findingcan be attributed to the dose of MT applied.