Effect of glutamine on Th1 and Th2 cytokine responses of human peripheral blood mononuclear cells

Decreased glutamine concentrations are found in patients with catabolic str ess and are related to susceptibility to infections. In this study, we eval uated the role of glutamine in Th1/Th2 cytokine responses. Peripheral blood mononuclear cells were stimulated with phytohemagglutinin (PHA), live atte nuated bacillus Calmette-Guerin (BCG), or measles virus in the presence of different glutamine concentrations. We found that glutamine at an optimal c oncentration (0.6 mM) significantly enhanced PHA-stimulated lymphocyte prol iferation as well as Th1 [interferon-gamma (IFN-gamma) and interleukin-2 (I L-2)] and Th2 cytokine (IL-4 and IL-10) production. In the absence of gluta mine, BCG and measles virus elicited minimal lymphocyte proliferation, wher eas BCG enhanced Th1 cytokine response and measles virus promoted Th2 cytok ine response. Interestingly, addition of glutamine promoted the BCG-elicite d Th1 cytokine response (IFN-gamma), but suppressed the measles-induced Th2 cytokine response (IL-10). These results suggest that appropriate glutamin e levels may influence host responses to different antigens and microorgani sms. Furthermore, predominately Th1, but not Th2, cytokine responses requir ed the presence of optimal concentrations of glutamine. (C) 1999 Academic P ress.