Department of Biology, Hamilton College, Clinton, NY, USA.
Academy for the Environment, University of Nevada Reno, NV, USA.
J Exp Zool A Ecol Integr Physiol. 2017 Jun;327(5):243-253. doi: 10.1002/jez.2081. Epub 2017 Jul 25.
An individual's investment in constitutive immune defenses depends on both intrinsic and extrinsic factors. We examined how Leucocytozoon parasite presence, body condition (scaled mass), heterophil-to-lymphocyte (H:L) ratio, sex, and age affected immune defenses in golden eagle (Aquila chrysaetos) nestlings from three regions: California, Oregon, and Idaho. We quantified hemolytic-complement activity and bacterial killing ability, two measures of constitutive immunity. Body condition and age did not affect immune defenses. However, eagles with lower H:L ratios had lower complement activity, corroborating other findings that animals in better condition sometimes invest less in constitutive immunity. In addition, eagles with Leucocytozoon infections had higher concentrations of circulating complement proteins but not elevated opsonizing proteins for all microbes, and eagles from Oregon had significantly higher constitutive immunity than those from California or Idaho. We posit that Oregon eagles might have elevated immune defenses because they are exposed to more endoparasites than eagles from California or Idaho, and our results confirmed that the OR region has the highest rate of Leucocytozoon infections. Our study examined immune function in a free-living, long-lived raptor species, whereas most avian ecoimmunological research focuses on passerines. Thus, our research informs a broad perspective regarding the evolutionary and environmental pressures on immune function in birds.
个体对固有免疫防御的投资取决于内在和外在因素。我们研究了莱氏血变原虫的存在、身体状况（体质量指数）、嗜中性粒细胞与淋巴细胞（H:L）比值、性别和年龄如何影响来自加利福尼亚州、俄勒冈州和爱达荷州三个地区的金雕雏鸟的免疫防御能力。我们量化了溶血补体活性和细菌杀伤能力，这两个都是固有免疫的衡量指标。身体状况和年龄并不影响免疫防御。然而，H:L 比值较低的雕体内的补体活性较低，这与其他研究结果一致，即身体状况较好的动物有时会较少地投资于固有免疫。此外，感染莱氏血变原虫的雕具有更高浓度的循环补体蛋白，但并非所有微生物的调理蛋白都升高，而且来自俄勒冈州的雕比来自加利福尼亚州或爱达荷州的雕具有更高的固有免疫能力。我们推测，俄勒冈州的雕可能具有更高的免疫防御能力，因为它们比加利福尼亚州或爱达荷州的雕暴露于更多的内寄生虫，而我们的结果也证实了 OR 地区的莱氏血变原虫感染率最高。我们的研究检验了一种自由生活的、长寿猛禽物种的免疫功能，而大多数鸟类生态免疫学研究都集中在雀形目鸟类上。因此，我们的研究为鸟类免疫功能的进化和环境压力提供了广泛的视角。
