The effect of glutamine-enriched TPN on gut immune cellularity

Abstract

Prolonged parenteral feeding with standard nutrient solutions results in significant alteration in the structural, hormonal, and immunological composition of the intestinal tract. The purpose of the following study was to evaluate the effect of glutamine-supplemented parenteral nutrition on the immune cellularity of the gut. Twenty-one Fischer rats were randomized to three groups of seven animals each. Group I was fed rat chow and water ad lib, Group II was fed a standard solution of total parenteral nutrition (TPN) (D25/4.25% amino acids) via a central venous catheter, and Group III was fed the standard solution of TPN with 2% glutamine which was isonitrogenous and isocaloric to Group II. Animals were fed their respective diets for 1 week and bile was collected and assayed for secretory IgA (s-IgA) and IgM. The terminal ileum was stained and assayed for IgA+, IgM+, IgG+, CD4+, and CD8+ plasma cells and lymphocytes. Results indicate that the feeding of a standard parenteral diet results in a significant decrease in biliary s-IgA and IgA+ plasma cells in the gut lamina propria compared to chow-fed animals (S-IgA: chow, 858 ± 23 μg/ml; TPN, 494 ± 41 μg/ml; IgA cells: chow, 35.7 ± 1.8; TPN, 8.6 ± 0.9 cells/hpf). In addition a marked depletion of CD4+ and CD8+ lymphocytes was observed with standard solutions of parenteral nutrition compared to chow (CD4+: chow, 36.8 ± 6.6; TPN, 14.9 ± 6.0; CD8+: chow, 18.8 ± 5.6; TPN, 5.7 ± 2.7 cells/hpf). The addition of glutamine to the standard TPN solution maintained both B and T cell populations at levels similar to chow-fed animals. Glutamine may be an important nutrient for gut immune function during prolonged parenteral feeding.