title: Specific and nonspecific immune responses to fasting and refeeding differ in healthy young adult and elderly persons.
abstract: BACKGROUND
  Undernutrition is a main cause of immunodeficiency. Many confounding factors limit the interpretation of immune function in hospitalized elderly patients.
  
  
  OBJECTIVE
  We compared the effects of short-term fasting and refeeding on lymphocyte subset distribution and neutrophil function in healthy subjects.
  
  
  METHODS
  Seven young adult (x +/- SE age: 24 +/- 2 y) and 8 elderly (71 +/- 3 y) subjects were fed standardized diets (1.6 x predicted resting energy expenditure; 16% protein) for 7 d. They then fasted for 36 h and were refed for 4 h (42 kJ/kg). Lymphocyte subsets were quantified by using fluorochrome-conjugated monoclonal antibodies. Neutrophil chemotactic migration was evaluated by using a 2-compartment chamber. Neutrophil reactive oxygen species production was measured by using a luminol-amplified chemiluminescence assay and oxidation of 2'7'-dichlorofluorescein diacetate.
  
  
  RESULTS
  Baseline total and cytotoxic T lymphocyte subpopulations were lower in elderly than in adult subjects (P < 0.01). Nutritional state had a significant effect (P < 0.05) on total, helper, and cytotoxic T and B lymphocyte counts in all subjects, and the response of lymphocyte subpopulations to nutritional fluctuations was significantly affected by age. The chemotactic index was lowered by fasting in both groups (P < 0.05 compared with basal values). After refeeding, neutrophil migration was restored in adult but not elderly subjects. The superoxide anion production rate increased with fasting and reverted to prefasting values with refeeding in both groups (P < 0.05). Fasting induced a significant decrease in hydrogen peroxide production in stimulated neutrophils that was reversed by refeeding in adult but not elderly subjects.
  
  
  CONCLUSIONS
  The lack of response of lymphocyte subpopulation counts and neutrophil function to nutritional changes may help to explain the proneness of elderly persons to infection.
authors.affiliation: Laboratoire de Biochimie, Biologie Moléculaire et Nutrition, Faculté de Pharmacie, Centre de Recherche en Nutrition Humaine, Clermont-Ferrand, France. stephane.walrand@u-clermont1.fr
authors.forename: S
authors.initials: S
authors.lastname: Walrand
authors.forename: K
authors.initials: K
authors.lastname: Moreau
authors.forename: F
authors.initials: F
authors.lastname: Caldefie
authors.forename: A
authors.initials: A
authors.lastname: Tridon
authors.forename: J
authors.initials: J
authors.lastname: Chassagne
authors.forename: G
authors.initials: G
authors.lastname: Portefaix
authors.forename: L
authors.initials: L
authors.lastname: Cynober
authors.forename: B
authors.initials: B
authors.lastname: Beaufrère
authors.forename: M P
authors.initials: MP
authors.lastname: Vasson
authors.forename: Y
authors.initials: Y
authors.lastname: Boirie
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000276:immunology*; D000911:Antibodies, Monoclonal / Q000032:analysis; D002452:Cell Count; D002634:Chemotaxis, Leukocyte / Q000276:immunology; D005215:Fasting / Q000502:physiology*; D005434:Flow Cytometry; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D007107:Immune System / Q000503:physiopathology*; D007109:Immunity / Q000502:physiology; D008163:Luminescent Measurements; D016131:Lymphocyte Subsets / Q000276:immunology*; D009504:Neutrophils / Q000276:immunology*; D009752:Nutritional Status; D010084:Oxidation-Reduction; D011502:Protein-Energy Malnutrition / Q000276:immunology*; D017382:Reactive Oxygen Species; D013481:Superoxides / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D017382:Reactive Oxygen Species; D013481:Superoxides; D006861:Hydrogen Peroxide