Abstract: Life history theory predicts that immune function, like other physiological activities such as thermogenesis and reproduction is energetically expensive. However, little experimental evidence for the energy cost to mount an immune response is available, and such costs may be affected by immunological parameters and assays selected. Therefore, the aim of this study was to explore the energetic cost of mounting an immune response in small mammals. We measured body mass and resting metabolic rate (RMR) at days 0 (before injection), and 5 and 10 days post-injection after a keyhole limpet haemocyanin (KLH) antigen challenge in male and female striped hamsters, Cricetulus barabensis. Concentrations of serum anti-IgM and IgG antibodies were measured by an ELISA assay using orbital venous blood samples. The results showed that: (1) Body masses of males were higher than for females, though no significant differences were found between the experimental and control groups by sex and time period after KLH challenge. (2) Concentrations of serum anti-IgM and IgG antibodies were higher in all KLH-challenged groups (i.e. females and males) than those of the controls. (3) RMR did not show apparent differences between control and KLH challenged groups by sex, and before-and-after KLH-challenge or within the different sampling time points (5 and 10 days post KLH injection). These results indicate that a single KLH challenge activated the humoral immunity of striped hamsters, but did not effect changes on body masses or energy expenditure under unlimited food availability. Possible explanations for these findings include that the cost of an enhancement of the humoral immunity may be at the expense of a reduction of another component of the immune system or that striped hamsters can build a humoral response to a mild immunological challenge without simultaneous extra energy cost.

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摘要： 根据生活史理论，免疫功能与产热和繁殖等其他生理学功能类似，具有能量代价。然而，关于提高免疫能力的能量学代价的实验例证很少，且此类代价可能受所选择的免疫学参数和实验测定的影响。为探究提高小型哺乳动物免疫能力的能量学代价，以匙孔血蓝蛋白（Keyhole limpet haemocyanin，KLH）作为外源抗原刺激，在注射前（第0天）、注射后第5天和第10天，分别测定非繁殖期雌、雄性黑线仓鼠（Cricetulus barabensis）体重和静止代谢率（Resting metabolic rate, RMR）的变化，通过眼眶静脉丛采血技术和ELISA分析，分别测定第5天（抗IgM抗体）和第10天（抗IgG抗体）动物血清抗体含量的变化。结果显示：（1）雄鼠的体重高于雌鼠，雌、雄鼠实验组和对照组之间的体重均无差异且不随时间而增加；（2）无论雌鼠还是雄鼠，注射KLH组血清中抗IgM和抗IgG抗体的含量均高于注射生理盐水的对照组动物；（3）注射KLH前后，RMR既无性别差异，也无组间差异，同一组动物的RMR均不随取样时间点而变化（KLH注射后第5天和第10天）。结果表明，单一的KLH刺激激活了黑线仓鼠的体液免疫，但在能量不受限的情况下不影响体重和能量收支的变化。有两种可能的解释：黑线仓鼠增强的体液免疫可能以免疫系统内另一免疫组分活动的降低作为代价，或它对体液免疫应答具有构建能力，温和的免疫刺激不伴随额外的能量学代价。

关键词: 黑线仓鼠, 体液免疫, 匙孔血蓝蛋白, 静止代谢率, 能量学代价