中文摘要：

目的 研究约氏疟原虫（Plasmodium yoelii）感染早期小鼠调节性T细胞（Treg）/辅助性T细胞17（Th17）比值变化。 方法 20只6～8周龄雌性BALB/c小鼠经腹腔注射1×106个约氏疟原虫17XL感染的红细胞，其中10只小鼠分别于感染前、后1 d注射1 mg CD25单克隆抗体（7D4），建立约氏疟原虫感染小鼠模型和Treg消除小鼠模型。于感染后1～7 d采小鼠尾静脉血，计数红细胞感染率，统计小鼠存活率。另取两模型组小鼠各10只，于感染前（0 d）、感染后3 d和5 d分别取3只小鼠脾组织，制备脾细胞悬液，流式细胞仪分别检测脾细胞中Treg和Th17数量占CD4＋ T细胞的百分比，计算Treg/Th17比值，分析Treg数量百分比与Th17数量百分比的相关性。 结果 约氏疟原虫17XL感染后2 d，感染组小鼠外周血中出现疟原虫感染的红细胞；感染后5 d，红细胞感染率上升至（49.8±4.7）%，小鼠存活率降至60.0%（6/10）；感染后6 d，小鼠全部死亡。Treg消除组小鼠也于感染后2 d外周血中出现疟原虫感染的红细胞，至感染后5 d红细胞感染率仅为（10.0±3.5）%，于感染后7 d上升至60.0%，感染后8 d小鼠全部死亡。感染后3 d，感染组小鼠Treg和Th17数量百分比分别为（11.1±1.3）%和（16.7±3.3）%，感染后5 d增加为（26.1±4.5）%和（19.6±2.6）%，均显著高于感染前［（5.0±0.7）%和（2.4±0.3）%］（P＜0.01）；感染后3 d和5 d 的Treg/Th17比值分别为0.7±0.1和1.3±0.4，均低于感染前（2.1±0.5）（P＜0.01，P＜0.05）；Treg消除组小鼠Treg和Th17数量于感染后3 d和5 d分别为（2.4±1.3）%、（4.3±2.9）%和（26.1±2.2）%、（6.5±2.1）%；Treg/Th17比值分别为0.1±0.1和0.7±0.4，均低于感染前（3.6±0.4）（P＜0.01）。相关性分析结果显示，Treg数量百分比与Th17数量百分比呈正相关（r=0.8166，P＜0.01）。 结论 约氏疟原虫17XL感染早期小鼠Tregs/Th17比值明显降低。

英文摘要：

Objective To investigate the change of Treg/Th17 cell ratio in mice infected with Plasmodium yoelii 17XL in the early stage of infection. Methods Forty 6-8 week-old female BALB/c mice were randomly divided into infection group and Treg blockade group. All the mice were infected by intraperitoneal injection with 1×106 P. yoelii 17XL-parasitized erythrocytes. Mice in Treg blockade group were intraperitoneally injected with 1 mg CD25 mAb before infection and on day 1 post-infection， respectively. Three healthy mice served as control. Tail vein blood samples were collected in two groups each with 10 mice during day 1-7 post-infection. The parasitemia was monitored daily by examining Giemsa-stained thin film. The survival rate of infected mice was calculated. Before infection, on day 3 and 5 post-infection， the spleen was aseptically removed from each mouse in infection group （n=3） and Treg blockade group （n=3）， and splenocyte suspensions were prepared. The proportion of Treg and Th17 cells were analyzed by flow cytometry. The ratio of Treg/Th17 cells was calculated and the relative analysis of the percentage of Treg and Th17 cells was conducted. Results Parasitemia appeared on day 2 post-infection in infection group. On day 5， the infection rate of P. yoelii in erythrocytes increased to （49.8±4.7）% with a survival rate of 60.0%. All mice died on day 6 post-infection. In Treg blockade group， P. yoelii 17XL-parasitized erythrocytes appeared on day 2 post-infection; the parasitemia was（10.0±3.5）% on day 5， and increased rapidly to 60.0% on day 7; all mice died on day 8. The percentages of Treg and Th17 cells reached（11.1±1.3）% and （16.7±3.3） % respectively on day 3 post-infection in infection group， and increased to（26.1±4.5）% and （19.6±2.6） % on day 5， considerably higher than that of the control（P＜0.01）. The ratio of Treg/Th17 cells was 0.7±0.1， 1.3±0.4 on day 3 and 5 post-infection in infection group， respectively， which was much lower than that of