日本血吸虫22.6kDa膜相关蛋白Th1型表位的免疫学鉴定

目的鉴定日本血吸虫22.6 kDa膜蛋白（Sj22.6）的Th1型表位,为构建短肽疫苗奠定基础。方法采用合成肽Sj22.6-P4、无关肽（对照）及PBS免疫C57BL/6小鼠2次（间隔7 d）,末次免疫后7～10 d取脾分离单个核细胞,用合成肽Sj22.6-P4、无关肽及PBS刺激培养,3H-TdR掺入法检测淋巴细胞的增殖效果,酶联免疫吸附试验（ELISA）检测其细胞培养上清中IFNγ-、IL-4及IL-2水平。运用流式细胞技术三色标记法检测经合成肽Sj22.6-P4、无关肽及PBS免疫2次的C57BL/6小鼠脾淋巴细胞内的Th1、Th2细胞因子。结果合成肽Sj22.6-P4可刺激经该抗原肽免疫2次的C57BL/6小鼠淋巴细胞增殖,与PBS组相比,增殖指数（SI）均〉2。与无关肽对照组相比,细胞培养上清中IL-2、IFN-γ分泌水平增高,其中IL-2分泌水平差异有统计学意义（P〈0.05）,IFN-γ差异无统计学意义（P〉0.05）,而IL-4分泌水平明显降低（P〈0.05）。合成肽Sj22.6-P4免疫组小鼠脾脏CD4＋T细胞中分泌IFN-γ细胞的百分比显著增高,分泌IL-4细胞的百分比显著降低（P均〈0.05）。结论合成肽Sj22.6-P4是C57BL/6小鼠特异的Th1型表位。

Immunological identification of Th1-type epitope in tegumental membrane-associated antigen Sj22.6 of Schistosoma japonicum

Objective To identify the T cell epitope Sj22.6-P4 in 22.6 kDa antigen of Schistosoma japonicum as a Th1-type epitope.Methods The synthetic peptide Sj22.6-P4,synthetic control peptide or PBS were used to immunize C57BL/6 mice twice（seven days interval）,respectively,and 7 days after the last vaccination,spleen mononuclear cells of the vaccinated mice were separated and stimulated with Sj22.6-P4,control peptide or PBS,respectively.The proliferation of spleen lymphocytes was detected by the 3H-thymidine assay,and the levels of IL-2,IFN-gamma and IL-4 in the cultural supernatant were detected by the ELISA assay.The spleen cells of vaccinated mice were separated for detecting the intracellular cytokines IFN-gamma and IL-4 by three-color flow cytometry.Results Compared with the control peptide or PBS groups,Sj22.6-P4 was able to effectively stimulate the lymphocyte proliferation（SI〉2）,and the high-level secretions of IL-2（P〈0.05） and IFN-gamma,and low level of IL-4（P〈0.05） of spleen lymphocytes in the Sj22.6-P4-immunized mice.In CD4＋T cells,the percentage of IFN-gamma-producing cells showed significantly higher while the proportion of IL-4-producing cells significantly lower in the Sj22.6-P4-immunized group,when compared with the control peptide-or PBS-immunized group（P〈0.05）.Conclusion Sj22.6-P4 is a Th1-type epitope specific for C57BL/6 mice.