Glycyl-L-Glutamine-Enriched Total Parenteral Nutrition Maintains Small Intestine Gut-Associated Lymphoid Tissue and Upper Respiratory Tract Immunity

ABSTRACT. Background: IV administration of a total parenteral nutrition (TPN) solution results in small intestinal gut-associated lymphoid tissue (GALT) atrophy, lowers small intestinal immu-noglobulin A (IgA) levels, and impairs upper respiratory tract secretory IgA-mediated mucosal immunity; isonitrogenous supplementation of TPN with 2 % glutamine attenuates these changes. This experiment examines whether a 2 % glycyl-L-glutamine-enriched TPN solution reverses IV TPN-induced changes as effectively as L-glutamine. Methods: Male Institute of Cancer Research (ICR) mice underwent intranasal inoculation with H1N1 influenza virus to establish immunity. After 3 weeks, mice were randomized to chow, IV feeding of a TPN solution, glutamine-enriched TPN, or glycyl-L-glutamine-enriched TPN. After 4 days of feeding, mice were challenged intranasally with influenza virus and killed at 40 hours to determine viral shed