Råberg Lars, Vestberg Mikael, Hasselquist Dennis, Holmdahl Rikard, Svensson Erik, Nilsson Jan-Ake
Department of Animal Ecology, Lund University, Ecology Building, S-223 62 Lund, Sweden.
Proc Biol Sci. 2002 Apr 22;269(1493):817-21. doi: 10.1098/rspb.2001.1953.
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.
除了祖先的固有免疫系统外，脊椎动物还进化出了适应性免疫系统。人们通常认为，防御的成本和收益之间的权衡支配着免疫防御的进化，但适应性免疫系统特有的成本和收益却鲜为人知。我们使用缺乏淋巴细胞的基因工程小鼠（即没有适应性免疫但有固有免疫的小鼠）作为脊椎动物免疫系统进化中祖先状态的模型。为了研究适应性防御的强度是否受到产生淋巴细胞等的能量成本的限制，我们比较了正常小鼠和缺乏淋巴细胞的小鼠的基础代谢率。我们发现，缺乏淋巴细胞的小鼠比具有固有免疫和适应性免疫防御的正常小鼠具有更高的基础代谢率。这表明适应性免疫系统的进化并没有受到能量成本的限制。相反，它应该受到与固有免疫和适应性免疫防御相结合相关的能量节省的青睐。
