性滥交会增加机体免疫力吗？

  研究者们推测，性滥交导致性传播疾病传播率的提高会影响哺乳动物免疫系统的重塑过程，近日一篇发表于国际杂志Functional Ecology上的研究报告中，来自德国莱布尼兹动物园等处的研究人员则表示，上述理论或许并不适用于啮齿类动物，对于啮齿类动物而言，生存情况和居住环境是决定其免疫力变化的关键因素。

  免疫系统可以保护有机体免于疾病，因此检测可以重塑免疫系统的因子对于人类和动物医学研究而言非常重要，其中一个主要的问题就是是否性传播疾病的暴露是引发哺乳动物免疫力改变的驱动因素；有证据表明，对于灵长类动物和肉食动物而言上述理论是成立的，目前研究人员认为这在哺乳动物体内也是成立的，如今研究人员利用啮齿类动物进行研究，其可以代表40%的所有生存的哺乳动物。

  文章中，研究人员对145篇涉及啮齿类动物的研究进行分析，从中收集数据，研究者利用白细胞和其两种主要组分：中性白细胞和淋巴细胞的总数量来作为检测免疫力的依据，通过测定睾丸质量来对研究对象患性传播疾病的风险进行定量，睾丸质量是一种检测啮齿类动物交配对象数量的预测子。在研究的同时研究人员也将机体质量差异和生存条件作为因素考虑了进去，结果显示，大型的啮齿类动物机体中的免疫细胞数量会增加，相比“放养”的动物而言，圈养的动物淋巴细胞计数水平较高；然而睾丸质量并不会因免疫力而改变，这就表明，性传播疾病在啮齿类动物机体免疫系统中并没有发挥重要作用。

  研究者Jundong Tian说道，我们都知道，性传播病原体的流行同免疫参数一样在不同的哺乳动物群体中发生着改变，而性传播疾病引发的压力并不是驱动所有哺乳动物免疫功能的决定子。

  最后研究者指出，鉴别出哺乳动物机体中可以重塑免疫力的关键因子或许可以帮助改进当前治疗疾病的疗法，而对啮齿类动物进行的研究结果也表明其同样适用于小鼠和大鼠中。（转化医学网360zhyx.com）

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转化医学网推荐的原文摘要：

Circulating white blood cell counts in captive and wild rodents are influenced by body mass rather than testes mass, a correlate of mating promiscuity
Functional Ecology Jundong Tian1,2,*, Alexandre Courtiol3, Karin Schneeberger4, Alex D. Greenwood1,2 andGábor Á. Czirják
Comparative studies of captive primates and carnivores have shown a positive correlation between total white blood cell (WBC) counts and the level of inferred mating promiscuity (e.g. using testes mass). This correlation has been interpreted to support the ‘sexually transmitted diseases (STDs)’ hypothesis, which states that differential spread of STDs is caused by variation in mating behaviour which shapes baseline aspects of the immune system in mammals.
In the present study, we tested the STDs hypothesis in rodents using 28 species from free-ranging and 9 species from captive populations. We compiled data set for the 9 studies of captive rodent populations from the International Species Information System (ISIS) and gathered 136 studies of wild populations from the literature.
Using phylogenetic generalized least-squares statistical models considering non-independence resulting from shared ancestry, we confirmed that species with greater adult body mass averaged across sexes had elevated total WBC and differential WBC (neutrophils and lymphocytes) counts and that captive animals presented higher lymphocyte counts than free-ranging ones.
However, we found that the total and differential WBC counts did not covary with the residual testes mass – a correlate of mating promiscuity. The results suggest that selection pressures caused by STDs may strongly vary among taxonomic groups. In order to determine the drivers of immunological variation among mammals, further comparative immunological studies including a wide range of taxonomic groups and socio-ecological variables should be performed and we recommend doing so by primarily focusing on free-ranging animals.