title: Carbohydrate intake during endurance exercise increases natural killer cell responsiveness to IL-2.
abstract: The purpose of this study was to evaluate the effect of high-intensity endurance exercise and carbohydrate consumption on in vitro responsiveness of natural killer (NK) to IL-2 (2.5 U/ml for 24 h). Thirteen male subjects (18-26 yr old; peak O2 consumption = 59.79 +/- 5.13 ml.kg-1.ml-1) were recruited to complete two 1-h (75-80% peak O2 consumption) cycling trials in a random counterbalanced order: carbohydrate (CHO) and placebo (Pla). Venous blood samples were collected before (Pre), immediately (Post), 2 h (2H), and 4 h (4H) after exercise. All resting samples were taken after 15 min of seated rest. NK (CD3-/56+), activated NK (CD3-/56+/69+), helper T cell (Th; CD3+/4+), and cytotoxic T cell (Tc; CD3+/8+) number were measured by using flow cytometry. NK cell activity (NKCA) was determined by using both a 51Cr release assay (NKCA-51) and activated NK cell number (NKCA-69). Immune system variables were not different between CHO and Pla, with the exception of NK cell responsiveness to IL-2, where Post (116.2%) and 4H (48.4%) was significantly greater in CHO (P < 0.05). NK, Th, and Tc were significantly higher Post (40.7, 102.7, and 82.0%, respectively) and lower at 2H (-51.9, -53.3, and -53.2%, respectively) than Pre (time effect). 4H was not different from Pre for NK, Th, and Tc. NKCA was significantly lower 2H (NKCA-51, NKCA-69) and 4H (NKCA-69) than Pre. CHO consumption during exercise did not prevent disruptions in unstimulated immune system function, but it did enhance NK responsiveness to IL-2.
authors.affiliation: Wastl Human Performance Laboratory, Department of Health and Kinesiology, Purdue University, West Lafayette, IN 47905, USA.
authors.forename: Brian K
authors.initials: BK
authors.lastname: McFarlin
authors.forename: Michael G
authors.initials: MG
authors.lastname: Flynn
authors.forename: Laura K
authors.initials: LK
authors.lastname: Stewart
authors.forename: Kyle L
authors.initials: KL
authors.lastname: Timmerman
mesh_terms: D000293:Adolescent; D000328:Adult; D015703:Antigens, CD / Q000494:pharmacology; D000945:Antigens, Differentiation, T-Lymphocyte / Q000494:pharmacology; D002860:Chromium Radioisotopes; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D005434:Flow Cytometry; D006339:Heart Rate; D006801:Humans; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000494:pharmacology*; D007694:Killer Cells, Natural / Q000187:drug effects / Q000276:immunology*; D037181:Lectins, C-Type; D007958:Leukocyte Count; D008213:Lymphocyte Activation / Q000187:drug effects; D008297:Male; D010101:Oxygen Consumption; D010807:Physical Endurance / Q000276:immunology*; D000099192:CD69 Antigens
chemical_list: D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D002860:Chromium Radioisotopes; D004040:Dietary Carbohydrates; D007376:Interleukin-2; D037181:Lectins, C-Type; D000099192:CD69 Antigens