Animals in the temperate zones face seasonal variations in environments and hence their immune responses change seasonally. In the current study, seasonal changes in hematological parameters and cytokines in striped hamsters (Cricetulus barabensis) were examined to test the winter immunoenhancement hypothesis, which states that immune function tends to increase in fall and winter compared with other seasons. Male and female hamsters were captured from the wild in the fall and winter of 2014 and in the spring and summer of 2015. Maximum body mass in both sexes and relative fatness in female hamsters occurred in the summer, indicating that body condition was the best during this season. All hematological parameters were not different between male and female hamsters, and were also not affected by the interaction of season and sex except neutrophil granulocytes (GRAN). Red blood cells (RBC) and haematocrit (PCV) were higher in the fall and winter, and hemoglobin concentration (HGB) was the highest in winter in hamsters compared with the spring and summer, implying that their oxygen-carrying capacity and oxygen affinity of the blood increased during these seasons. Compared with other seasons, the number of white blood cells (WBC) was higher in winter than in summer, intermediate granulocytes (MID), the percent of MID (MID%), GRAN and the percent of GRAN (GRAN%) were the highest in winter, which all supported the winter immunoenhancement hypothesis. However, the count of lymphocytes (LYMF) was the highest in spring, being inconsistent with this hypothesis. IL-2 levels, but not TNF-α, were influenced by seasons, sex and their interaction in hamsters. Regardless of sex, IL-4 titres were higher in spring and summer than in fall and winter in hamsters. INF-γ titres in male hamsters did not differ between the spring and summer, while its titres in female hamsters was lower in spring in contrast with winter and summer. Higher IL-2 and IL-4 levels during the breeding seasons might be crucial in controlling the increased possibilities of infections in these seasons. In summary, season and sex had disparate effects on different hematological profiles and the levels of cytokines in hamsters.

中文翻译：

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季节和性别对条纹仓鼠（Cricetulus barabensis）血液学和细胞因子的影响不同

温带地区的动物面临环境的季节性变化，因此它们的免疫反应会随季节变化。在目前的研究中，检查了条纹仓鼠（Cricetulus barabensis）血液学参数和细胞因子的季节性变化，以检验冬季免疫增强假说，该假说指出，与其他季节相比，秋季和冬季的免疫功能往往会增加。雄性和雌性仓鼠分别于2014年秋冬季和2015年春夏季从野外捕获。雌性和雌性仓鼠的最大体重和相对肥胖发生在夏季，表明其体况最好这一季。雄性和雌性仓鼠之间的所有血液学参数都没有差异，除中性粒细胞（GRAN）外，也不受季节和性别相互作用的影响。秋季和冬季的红细胞（RBC）和血细胞比容（PCV）较高，仓鼠的血红蛋白浓度（HGB）与春季和夏季相比在冬季最高，说明仓鼠的携氧能力和亲氧性为在这些季节，血液增加了。与其他季节相比，冬季白细胞（WBC）数高于夏季，中间粒细胞（MID）、MID百分比（MID%）、GRAN和GRAN百分比（GRAN%）最高在冬季，这些都支持冬季免疫增强假说。然而，淋巴细胞计数（LYMF）在春季最高，与这一假设不一致。IL-2 水平，但不是 TNF-α，受季节影响，性及其在仓鼠中的相互作用。无论性别如何，仓鼠的 IL-4 滴度在春季和夏季都高于秋季和冬季。雄性仓鼠的 INF-γ 滴度在春季和夏季之间没有差异，而雌性仓鼠的 INF-γ 滴度在春季低于冬季和夏季。繁殖季节期间较高的 IL-2 和 IL-4 水平对于控制这些季节感染的可能性增加可能至关重要。总之，季节和性别对仓鼠的不同血液学特征和细胞因子水平有不同的影响。与冬季和夏季相比，春季雌性仓鼠的滴度较低。繁殖季节期间较高的 IL-2 和 IL-4 水平对于控制这些季节感染的可能性增加可能至关重要。总之，季节和性别对仓鼠的不同血液学特征和细胞因子水平有不同的影响。与冬季和夏季相比，春季雌性仓鼠的滴度较低。繁殖季节期间较高的 IL-2 和 IL-4 水平对于控制这些季节感染的可能性增加可能至关重要。总之，季节和性别对仓鼠的不同血液学特征和细胞因子水平有不同的影响。