Activity of natural killer cells after postoperative amino acid infusion

Effects of postoperative infusion of a 3% amino acid solution on natural killer (NK) cell activity were studied in 10 patients undergoing major abdominal surgery. Eight additional patients formed the control group. Preoperative NK cell activity against K562 target cells determined in a short-term 51Cr release assay was similar in patients of both groups. After the operation, in general the patients of both groups showed a decrease in NK cell activity (p less than 0.01) but without differences between the groups. There were no changes in the percentages of Leu-7 positive cells (NK cells) between or within the two groups. However, the number of Leu-7 positive cells in blood was lower in the amino acid than in the control group patients during the postoperative days 3-7 (p less than 0.05 and 0.01). In vitro, the amino acid solution proved to be nontoxic both for effector and target cells and no depression of NK cell activity was observed. A 16-hr preincubation of mononuclear cells with the amino acid solution did not affect NK cell activity. The results suggest that postoperative infusion of an isotonic amino acid solution does not routinely offer any advantages over glucose containing electrolyte solution as to its effects on NK cell activity.