中文摘要：

目的探讨转染可溶性CD40（sCD40）基因的树突状细胞（DC）在体外对T淋巴细胞增殖和细胞毒性T淋巴细胞（CTL）的细胞毒活性的影响。方法采用脂质体转染法，将携带鼠CD40胞外区和绿色荧光蛋白的融合基因的质粒pEGFP-N1／sCD40转染小鼠DC细胞株（DC2．4）。以Balb／c小鼠淋巴细胞为反应细胞，分别以转染组DC、空载体转染组（空载体组）DC和未行转染处理的DC（空白DC）作为刺激细胞，进行单向混合淋巴细胞培养，四唑氮化合物比色法检测细胞增殖情况。用乳酸脱氢酶释放试验和流式细胞术检测转染组DC及其培养上清液对CTL细胞毒活性及其凋亡的影响。结果转染组DC及其培养上清液对同种细胞刺激的淋巴细胞增殖反应有显著的抑制作用（P〈0．05），并对特异性CTL的细胞毒活性具有明显的抑制作用（P〈0．05）；转染组DC可诱导CTL凋亡（P〈0．05）。结论稳定表达sCD40-EGFP融合蛋白的DC，在体外对T淋巴细胞的增殖和CTL的细胞毒活性具有明显的抑制作用，并可诱导CTL凋亡。

英文摘要：

Objective To study the effect of dendritic cells （DCs） transfected with sCD40- EGFP on T-cell proliferation and the cytotoxic T lymphocyte cytotoxic activity. Methods The expressing vector pEGFP-N1/sCD40 was transfected into DCs via lipofectamine reagent mediation. Peripheral blood mononuclear cells （PBMCs） from Balb/c mice as reaction cells and DCs from sCD40 transfection group, empty vector transfection group and non-transfection group as stimulation cells were subjected to mixed lymphocyte culture （MLC）. MTS colorimetry was used to detect lymphocyte proliferation. Lactate dehydrogenase release method and flow cytometry were used to detect the effect of DCs in sCD40 transfection and the culture supernatants on cytotoxic activity of specific cytotoxic T lymphocytes and T-cell apoptosis. Results DCs and the culture supematants in sCD40 transfection group could significantly inhibit lymphocyte proliferation response stimulated by allogenic cells and cytotoxic activity of specific cytotoxic T lymphocytes, and could induce CTL apoptosis. Conclusion The DCs stably expressing sCD40-EGFP fusion protein could not only significantly inhibit T-cell proliferation and cytotoxic activity of CTL, but also induce CTL apoptosis.