蛇源裂头蚴感染小鼠空肠免疫球蛋白A抗体分泌细胞数量及分泌型免疫球蛋白A水平观察

Observation of immunoglobulin A secreting cells and secretory immunoglobulin A in jejunum of mice infected with plerocercoids in snakes

目的 观察蛇源裂头蚴感染小鼠诱导免疫球蛋白A（IgA）抗体分泌细胞（IgASCs）数量及分泌型IgA（sIgA）抗体应答水平，了解IgASCs及sIgA在抗裂头蚴入侵中的作用。方法 选取清洁级昆明小鼠100只，雌雄各半，体重为20 ~ 25 g，按体重采用随机数字表法分为对照组和实验组，每组50只。用蛇源裂头蚴喂饲实验组小鼠，每只喂5条；对照组不感染。分别于感染后1、7、14、28、56 d从2组中各取10只小鼠进行解剖，收集空肠液和空肠段组织。采用免疫组织化学法检测空肠黏膜中IgASCs数量，酶联免疫吸附实验（ELISA）检测空肠液sIgA水平。结果 IgASCs分布于空肠黏膜的固有层中，实验组IgASCs数量（以IgASCs阳性细胞率表示）于感染后1 d达到峰值［（64.24 ± 0.60）%］，随后下降，至感染后14 d［（41.98 ± 0.42）%］低于对照组［（43.52 ± 0.94）%，t = - 4.727，P 〈 0.01］。实验组sIgA水平于感染后7 d达到峰值［（22.05 ± 1.43）mg／L］，随后呈下降趋势，于感染后56 d［（21.26 ± 2.59）mg／L］与对照组［（20.00 ± 0.42）mg／L］比较差异无统计学意义（t = 1.516，P 〉 0.05）。实验组感染后7 d，空肠黏膜IgASCs数量与空肠液sIgA水平呈正相关（r = 0.663，P 〈 0.01），而在感染后14 d，二者呈负相关（r = - 0.542，P 〈 0.05）。结论 小鼠感染蛇源裂头蚴后，可诱导IgASCs高水平的表达及sIgA水平的升高，二者在感染后7 d呈正相关。

Objective To observe the immunoglobulin A secreting cells （IgASCs） and secretory IgA （sIgA） level in jejunum of mice infected with plerocercoids, and to understand the roles of resistance to invasion processes of the plerocercoids. Methods A total of 100 Kunming mice （half males and half females） were chosen, the weight was 20 - 25 g, they were randomly divided into control and experiment groups according to their body weight via the random number table method, 50 per group. Mice of experiment group were fed each with 5 plerocercoids in snakes, and mice of control group were not infected, testing time and methods were the same in the two groups. Ten mice were randomly sacrificed from one group on days 1, 7, 14, 28 and 56 after infection, to collect empty intestinal juice and jejunal segment. The immunohistochemical method was used to examine the quantity of IgASCs in jejunal mucosa, while enzyme-linked immunosorbent assay （ELISA） was applied to test the level of slgA of jejunal fluid. Results The IgASCs were distributed in lamina propria of the jejunal mucosa, and the percentage of positive IgASCs reached the peak value [（64.24 ± 0.60）%] at d 1 after infection in experiment group, then decreased, and it was lower than control group at d 14 [（41.98 ± 0.42）% vs （43.52 ± 0.94）%, t = - 4.727, P 〈 0.01]. The sIgA level reached the peak value [（22.05 ± 1.43） mg/L] at d 7 after infection in experiment group, then decreased, and there was no statistical significant difference between control and experiment groups at d 56 [（20.00 ± 0.42） mg/L vs （21.26 ± 2.59） mg/L, t = 1.516, P 〉 0.05]. There was a positive correlation between the percentage of positive IgASCs in the jejunal mucosa and sIgA level in the jejunal fluid at d 7 after infection （r = 0.663, P 〈 0.01）, and there was a negative correlation between them at d 14 after infection （r = - 0.542, P 〈 0.05）. Conclusion The plerocercoids infection might induce high level expressions of IgASCs and sIgA, they show positive correlation at d 7 after infection.