Supplemental glutamine augments phagocytosis and reactive oxygen intermediate production by neutrophils and monocytes from postoperative patients in vitro

The energy substrate for neutrophils has been believed to be glucose. Howev er, a recent investigation has demonstrated that neutrophils use glutamine (Gln) as well as glucose. Nevertheless, little is known about the effects o f Gin on neutrophil function. Thus, this study was designed to investigate the effects of Gin on phagocytosis and reactive oxygen intermediate (ROI) p roduction by neutrophils from postoperative patients in vitro. Eleven patie nts who had undergone major gastrointestinal surgery were randomly selected . Peripheral blood was drawn before surgery and on postoperative days (PODs ) 1, 3, and 7. The blood was washed with medium to remove plasma. Washed wh ole blood was incubated in RPMI 1640 medium containing neither Gin nor gluc ose for 24 h at 37 degrees C. The medium was supplemented with Gin at a con centration of 0, 500, 1000, or 2000 mu M. Whole blood was then assessed for phagocytosis by flow cytometry using fluorescent beads. ROI production by phagocytes was measured by flow cytometry using dihydrorhodamine 123. in ea ch assay, the neutrophil population was gated and analyzed. Serum amino aci ds were also measured. Postoperative serum Gin level decreased significantl y until POD 7. Phagocytosis by neutrophils on PODs 3 and 7 was significantl y greater at 2000 mu M Gin than at other Gin concentrations. Neutrophil ROI production was significantly greater at 2000 mu M Gin than at 0 mu M Gin a t each time point. in conclusion, supplemental Gin enhances both phagocytos is and ROI production by neutrophils from postoperative patients in vitro. (C)Elsevier Science Inc. 2000.