中文摘要：

目的探讨斯氏艾美球虫（Eimeria stiedai）可溶性蛋白（EsSP）对荷瘤小鼠肿瘤生长、生存率和免疫状态的影响。方法建立小鼠皮下结肠癌（CT26）肿瘤模型，确定最小100％致瘤量肿瘤细胞数。取10^8个斯氏艾美球虫孢子化卵囊．采用超声波间断乳化制备EsSP。105只雄性BALB／c小鼠按随机数表法均分为7组（15只／组）．每组小鼠于右侧腋窝皮下接种CT26细胞5×10^5个，其中6个实验组（A-F组）小鼠分别腹腔注射100．00、50．00、10．00、1．00、0．10、0．01μg／dEsSP，1次／d×5d，对照组腹腔注射等量PBS。于接种后第7、11、13、15、17、19、21、23天测量肿瘤直径，计算相对肿瘤体积和相对肿瘤增殖率（T／C）。接种后第25天每组各处死5只小鼠．称量瘤重．计算抑瘤率。采眼球血，分离小鼠外周血淋巴细胞，MTS比色法检测EsSP对荷瘤小鼠淋巴细胞增殖能力的影响。计算刺激指数（SI）；流式细胞术检测外周血CDg＋／CD8＋T淋巴细胞比值变化。记录各组荷瘤小鼠死亡时间和死亡数量．共观察80d。各组间差异性比较采用单因素方差分析。结果最小100％致瘤量肿瘤细胞数为5×105个。接种结肠癌细胞后第23天，A、B、C组的肿瘤体积为（435．2±41．1）、（366．3±29．2）、（460．2±28．5）mm^3，较E、F和对照组的（761．2±33．2）、（810．4±38．4）、（865．2±35．3）mm^3生长缓慢（P〈0．05）；A、B、C组的T／C分别为（39．0±6．7）％、（33．3±8．9）％、（35．0±8．1）％，均〈40％。B组小鼠瘤重为（1．109±0．432）g，低于对照组的（1．946±0．289）g（P〈0．05），抑瘤率最高，为（43．0±14．6）％。MTS比色法检测结果显示．B、C组小鼠S1分别为1．75±0．15、1．70±0．32，高于对照组的1．38±0．18（P〈0．05）。流式细胞术检测结果显示，A、B、C组小鼠外周血中CD4＋／CD8＋T淋巴细胞亚群的?

英文摘要：

Objective To investigate the effect of soluble protein from Eimeria stiedai （EsSP） on tumor growth, survival and immune status in tumor-bearing mice. Methods The minimum number of tumor cells that caused tumorigenesis was determined to establish a mouse model of subcutaneous colorectal cancer （CT26）. EsSP was prepared from l0s E.stiedai sporulated oocysts by ultrasonic intermittent emulsification. One hundred and five BALB/c mice were randomly assigned into 7 groups, each receiving a subcutaneous injection of 5×10^5 CT26 cells at the right flank. Six experiment groups （A-F） were also injected intraperitoneally with different doses of EsSP （100.00, 50.00, 10.00, 1.00, 0.10, and 0.01 μg） once a day for 5 days, respectively. The control group were injected with the same volume of PBS. The tumor diameter was measured at 7, 11, 13, 15, 17, 19, 21, 23 days after inoculation, and the relative minor volume and relative tumor proliferation rate （T/C） were calculated. Five mice in each group were sacrificed on day 25 after inoculation. The tumor was weighed and tumor inhibition rate was calculated. Orbital blood was collected to isolate peripheral lymphocytes. The effect of EsSP on the proliferation of lymphocytes in tumor-bearing mice was assessed by MTS colorimetric assay, and the stimulus index （SI） was calculated. CD4±/ CD8± T lymphocyte ratio in peripheral blood was determined by flow cytometry. The time and number of death were recorded for 80 days. Data were analyzed by one-way ANOVA. Results The minimum amount of tumor cells for tumorigenesis was 5 × 10^5 cells. At 23 days after inoculation, the tumor volumes in groups A, B and C were （435.2 ± 41.1） mm3, （366.3 ± 29.2） mm3, and （460.2 ± 28.5） mm3, respectively, which were significantly smaller than （761.2± 33.22） mm3, （810.4 ± 38.36） mm3 and （865.2 ± 35.29） mm3 in groups E and F and control group, respectively （P 〈 0.05）. The T/C values in groups A, B and C were （39.0 ± 6.7）%, （33.3± 8.9）%,