Gastrin, Secretin, GIP and VIP Alter Levels of IL-2 and IFN-y in Human Peripheral Blood Mononuclear Cells under Various Culture Conditions

Background: Gastrointestinal hormones have traditionally been viewed as mere regulators of gut movement and secretions, but, it is becoming increasingly apparent that other body systems may be affected by these hormones. Secretion of gut hormones is influenced by the type of food we take. Therefore, the more we know about the effects of gut hormones on the various body tissues, the more we know about the different mechanisms by which our diets affect our health. Objectives: This in vitro study aimed to explore the effects of physiologically-relevant concentrations of four gut hormones on the production of IL-2 and IFN-y by human peripheral blood mononuclear cells and how culture conditions may modify those effects. Methods: Peripheral blood mononuclear cells were separated by density gradient centrifugation from the blood of 15 adults. Cells were cultured with/without PHA and treated with four concentrations of gastrin, secretin, GIP and VIP. IL-2 and IFN-y in culture supernatants were assayed by ELISA. Results: Gastrin, secretin, GIP and VIP increased IL-2 and IFN-y levels under some culture conditions and depressed IL-2 under other conditions. An increase was often observed under culture conditions in which the cytokine production was not initially high. Repeated administration of the hormone was also more likely to result in a stimulatory effect. Conclusions: Physiologically-relevant concentrations of gastrin, secretin, GIP and VIP are potential immunomodulators as they have shown their ability to alter the production of I L -2 and/or IFN-y under various culture conditions.