Basal metabolic rate and the evolution of the adaptive immune system.
Vertebrates have evolved an adaptive immune system in addition to the ancestral innate immune system. It is often assumed that a trade-off between costs and benefits of defence governs the evolution of immunological defence, but the costs and benefits specific to the adaptive immune system are poorly known. We used genetically engineered mice lacking lymphocytes (i.e. mice without adaptive, but with innate, immunity) as a model of the ancestral state in the evolution of the vertebrate immune system. To investigate if the magnitude of adaptive defence is constrained by the energetic costs of producing lymphocytes etc., we compared the basal metabolic rate of normal and lymphocyte-deficient mice. We found that lymphocyte-deficient mice had a higher basal metabolic rate than normal mice with both innate and adaptive immune defence. This suggests that the evolution of the adaptive immune system has not been constrained by energetic costs. Rather, it should have been favoured by the energy savings associated with a combination of innate and adaptive immune defence.
Råberg
Lars
L
Department of Animal Ecology, Lund University, Ecology Building, S-223 62 Lund, Sweden. lars.raberg@zooekol.lu.se
Vestberg
Mikael
M
Hasselquist
Dennis
D
Holmdahl
Rikard
R
Svensson
Erik
E
Nilsson
Jan-Ake
JA
D000222:Adaptation, Physiological; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology; D001481:Basal Metabolism; D005075:Biological Evolution; D004734:Energy Metabolism; D007109:Immunity; D008231:Lymphopenia / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D018448:Models, Immunological; D011947:Receptors, Antigen, B-Cell / Q000235:genetics; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics; D013601:T-Lymphocytes / Q000276:immunology
D011947:Receptors, Antigen, B-Cell; D016693:Receptors, Antigen, T-Cell, alpha-beta