title: Costs of immune response in cold-stressed laboratory mice selected for high and low basal metabolism rates.
abstract: To study whether mounting an immune response is energetically costly, mice from two lines divergently selected for high (H-BMR) and low (L-BMR) basal metabolic rate (BMR) were immunized with sheep red blood cells. Their energy budgets were then additionally burdened by sudden transfer from an ambient temperature of 23 degrees C to 5 degrees C. We found that the immune response of H-BMR mice was lower than that of L-BMR mice. However, the interaction between line affiliation and ambient temperature was not significant and cold exposure did not result in immunosuppression in either line. At 23 degrees C the animals of both lines seemed to cover the costs of immune response by increasing food consumption and digestive efficiency. This was not observed at 5 degrees C, so these costs must have been covered at the expense of other components of the energy budget. Cold exposure itself elicited a considerable increase in food intake and the mass of internal organs, which were also heavier in H-BMR than in L-BMR mice. However, irrespective of the temperature or line affiliation, immunized mice had smaller intestines, while cold-exposed immunized mice had smaller hearts. Furthermore, the observed larger mass of the liver and kidneys in immunized mice of both lines kept at 23 degrees C was not observed at 5 degrees C. Hence, immunization compromised upregulation of the function of metabolically active internal organs, essential for meeting the energetic demands of cold. We conclude that the difficulties with a straightforward demonstration of the energetic costs of immune responses in these animals stem from the extreme flexibility of their energy budgets.
authors.affiliation: Institute of Biology, University of Białystok, Swierkowa 20b, 15-950, Białystok, Poland. anetak@uwb.edu.pl
authors.forename: Aneta
authors.initials: A
authors.lastname: Ksiazek
authors.forename: Marek
authors.initials: M
authors.lastname: Konarzewski
authors.forename: Magdalena
authors.initials: M
authors.lastname: Chadzińska
authors.forename: Mariusz
authors.initials: M
authors.lastname: Cichoń
mesh_terms: D000818:Animals; D001481:Basal Metabolism / Q000502:physiology*; D001824:Body Constitution / Q000502:physiology; D003080:Cold Temperature; D004734:Energy Metabolism / Q000502:physiology; D007165:Immunosuppression Therapy; D051379:Mice / Q000276:immunology* / Q000378:metabolism / Q000502:physiology; D013312:Stress, Physiological / Q000276:immunology*