The in vivo and in vitro Effects of Caffeine on Rat Immune Cells Activities: B, T and NK Cells

The effect of caffeine (naturally occurring plant methylxanthlne) on Immunological cell activities in Sprague-Dawley rat both in vivo and in vitro was studied. A cytotoxic assay was done to study natural killer (NK) cells and a proliferation assay was performed for T and 8 cell activities. Three different doses of caffeine i.e., 2, 8 and 18 mg/kg/day were administered chronically to Sprague-Dawley rats to assess the effects in vivo. 80th NK cell cytotoxicity and 8 cell proliferative response to pokeweed mitogen (PWM) showed significant decreases (P < 0.05) In rats treated with 6 mglkglday, whereas the T cell proliferative response to phy. tohemagglutlnln·P (PHA·P) was significantly increased (P< 0.05) In the rats treated with 18 mg/kglday. In vitro, caffeine significantly decreases (P< 0.05) 8 and T cell proliferative responses to PWM and PHA·P at added caffeine concentrations of 10, 20 and 40jJg/ml. However, no effect was observed on NK cells activity. Furthermore, in vitro, a broader dose range of caffeine (1,10,100 and 1,000 J1g/ml) exhibited dosedependent Inhibition of both 8 and T cell proliferative responses.