title: Effects of food restriction in military training on T-lymphocyte responses.
abstract: In a stress model which included food restriction, we examined the effects of physically rigorous military training and increased caloric intake on T-lymphocyte responses and lymphocyte subsets. T-lymphocyte proliferation and release of soluble receptor for interleukin-2 (slL-2R) in vitro were measured in two separate training classes of male U.S. Army ranger course (RC) trainees at the start and during the RC. Trainees in group 1 (n = 55) and 2(n = 50), respectively, had mean (+/- SD) energy intakes of 11.8 +/- 7.0 and 13.6 +/- 6.7 MJ/d, averaged total daily energy expenditures of 16.7 and 17.6 MJ/d, and experienced body weight losses of 15.]% and 12.6%. Both groups showed decreases T-lymphocyte responses in vitro: proliferation to phytohemagglutinin (PHA) and tetanus toxoid (TT), and released slL-2R to PHA. Group 2 with an intended 15% increase in energy during the RC over group 1 showed 22% and 26% less severe suppressions of T-lymphocyte proliferation and released slL-2R, respectively, in vitro. Group 2 also showed that short-term (9 days) removal of the food restriction stressor allowed for corrected body weight, total lymphocyte and T-lymphocyte subset counts but not suppressed T-lymphocyte responses in vitro. These results demonstrate that soldiers in physically rigorous military training are at risk of suppressed T-lymphocyte immunocompetence, and this is greater if they also experience inadequate energy intake.
authors.affiliation: USDA Carotenoid Research Unit, Beltsville Human Nutrition Research Center, MD, USA.
authors.forename: T R
authors.initials: TR
authors.lastname: Kramer
authors.forename: R J
authors.initials: RJ
authors.lastname: Moore
authors.forename: R L
authors.initials: RL
authors.lastname: Shippee
authors.forename: K E
authors.initials: KE
authors.lastname: Friedl
authors.forename: L
authors.initials: L
authors.lastname: Martinez-Lopez
authors.forename: M M
authors.initials: MM
authors.lastname: Chan
authors.forename: E W
authors.initials: EW
authors.lastname: Askew
mesh_terms: D000328:Adult; D002149:Energy Intake / Q000276:immunology*; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology*; D006801:Humans; D007108:Immune Tolerance / Q000502:physiology; D066298:In Vitro Techniques; D008213:Lymphocyte Activation; D016131:Lymphocyte Subsets; D008297:Male; D008889:Military Personnel; D015375:Receptors, Interleukin-2 / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D015375:Receptors, Interleukin-2