Effect of glutamine on immune function in the surgical patient

The beneficial effects of glutamine on immune function in vitro have been well described. Severely ill surgical patients undergo glutamine depletion and this has been implicated as a cause of immune dysfunction in vivo. With the introduction of the stable dipeptides of glutamine into total parenteral nutrition (TPN) regimens, the clinical effects of glutamine on the immune system have taken on an increased relevance and importance. In a randomized clinical trial, we have shown that glutamine-supplemented TPN increased the T cell mitogenic response in patients undergoing colorectal resection. This was not associated with an altered production of the pro-inflammatory cytokines interleukin-6 (IL-6) or tumor necrosis factor (TNF). In a subsequent clinical trial comparing glutamine-supplemented TPN with control TPN in patients with severe acute pancreatitis there was a similar modest enhancement of the T cell response in the glutamine-supplemented group. Although Il-6 and TNF production were again unchanged, there was a significant reduction in IL-8 production in the glutamine-supplemented group. Glutamine may exert its immunological effects by a direct action on the cells of the immune system. Possible indirect mechanisms by which glutamine may influence the immune system include the maintenance of gut barrier function, or the preservation of action of the antioxidant glutathione.