Motz Victoria L, Lewis William D, Vardo-Zalik Anne M
The Pennsylvania State University, York Campus, 1031 Edgecomb Avenue, York, Pennsylvania 17403. Correspondence should be sent to:
J Parasitol. 2014 Oct;100(5):592-7. doi: 10.1645/13-371.1. Epub 2014 Jun 19.
Plasmodium mexicanum is a malaria parasite that naturally infects the western fence lizard, Sceloporus occidentalis , in northern California. We set out to determine whether lizards naturally infected with this malaria parasite have different leukocyte profiles, indicating an immune response to infection. We used 29 naturally infected western fence lizards paired with uninfected lizards based on sex, snout-to-vent length, tail status, and the presence-absence of ectoparasites such as ticks and mites, as well as the presence-absence of another hemoparasite, Schellackia occidentalis. Complete white blood cell (WBC) counts were conducted on blood smears stained with Giemsa, and the proportion of granulocytes per microliter of blood was estimated using the Avian Leukopet method. The abundance of each WBC class (lymphocytes, monocytes, heterophils, eosinophils, and basophils) in infected and uninfected lizards was compared to determine whether leukocyte densities varied with infection status. We found that the numbers of WBCs and lymphocytes per microliter of blood significantly differed (P < 0.05) between the 2 groups for females but not for males, whereas parasitemia was significantly correlated with lymphocyte counts for males, but not for females. This study supports the theory that infection with P. mexicanum stimulates the lizard's immune response to increase the levels of circulating WBCs, but what effect this has on the biology of the parasite remains unclear.
墨西哥疟原虫是一种疟疾寄生虫，它自然感染加利福尼亚北部的西部围栏蜥蜴（侧斑鬣蜥）。我们着手确定自然感染这种疟疾寄生虫的蜥蜴是否具有不同的白细胞谱，这表明对感染有免疫反应。我们使用了29只自然感染的西部围栏蜥蜴，并根据性别、吻肛长度、尾巴状况以及蜱和螨等外寄生虫的有无，还有另一种血液寄生虫——西方谢尔拉克虫的有无，将它们与未感染的蜥蜴配对。对用吉姆萨染色的血涂片进行全白细胞（WBC）计数，并使用禽类白细胞分类法估计每微升血液中粒细胞的比例。比较感染和未感染蜥蜴中各类白细胞（淋巴细胞、单核细胞、嗜异性粒细胞、嗜酸性粒细胞和嗜碱性粒细胞）的丰度，以确定白细胞密度是否随感染状态而变化。我们发现，每微升血液中的白细胞和淋巴细胞数量在两组雌性蜥蜴之间有显著差异（P < 0.05），而在雄性蜥蜴中没有差异，而疟原虫血症与雄性蜥蜴的淋巴细胞计数显著相关，但与雌性蜥蜴无关。这项研究支持了这样一种理论，即感染墨西哥疟原虫会刺激蜥蜴的免疫反应，以增加循环白细胞的水平，但这对寄生虫生物学有何影响仍不清楚。
