【摘要】 目的:探讨小鼠髓系DCs表面PD- L1分子在树突状细胞介导T细胞免疫应答中的作用。方法:采用流式细胞术分别检测未成熟DCs和凋亡肿瘤细胞负载并经CD4 0配基化的成熟DCs表面免疫分子的表达;混合淋巴细胞反应(MLR)和抗PD- L1单抗阻断试验分析未成熟DCs和成熟DCs表达的PD L1分子对T淋巴细胞的协同刺激 抑制效应;3H -TdR掺入试验检测未成熟DCs和成熟DCs对T淋巴细胞的促增殖效应;ELISA测定各组MLR反应上清中IL -10、IFN- γ的分泌水平;MTT比色法检测成熟DCs激发的肿瘤抗原特异性CTL对肿瘤细胞的杀伤效应。结果:未成熟DCs表面高表达PD- L1,负性调节未成熟DCs对自体T淋巴细胞的促增殖作用,抑制T细胞分泌IL -10、IFN -γ;凋亡肿瘤细胞负载并经CD4 0配基化的成熟DCs中等水平表达PD- L1,具有显著增强对自体T细胞的体外激发、扩增和细胞毒效应的作用,并可增加T细胞的IFN γ分泌。结论:未成熟DCs高表达PD -L1抑制了对T细胞共刺激效应;CD4 0配基化成熟的DCs中度表达PD -L1有助于激发T细胞介导免疫应答。更多还原

【Abstract】 Objective:To study the role of PD-L1 on the surface of mouse myeloid DCs(CD8α -) in the dendritic cell mediated T cell immune response.Methods:Expressions of PD-L1 and other phenotypes of immature dendritic cells (imDC) and CD40 ligation mature dendritic cells(mDC) were analyzed by FCM. 3H-thymidine incorporation test was used to detect the T cell proliferation stimulated by imDC and mDC with or without blocking PD-L1 by mAb respectively. The concentrations of IL-10 and IFN-γ in supernatants of MLR from distinct groups were analyzed by ELISA. MTT assay was used to detect the cytolytic activity of CTL stimulated by DCs.Results:Blockade of PD-L1 on imDC expressing high levels of PD-L1 promotes T cell proliferation and enhances IL-10 and IFN-γ secretion. Loaded by apoptotic tumor cells, CD40 ligation mDC expresses low levels of PD-L1, and blockade of PD-L1 on mDC inhibits T cell proliferation and cytolytic effect of CTL and downregulates IFN-γ secretion.Conclusion:High level of PD-L1 on imDC might contribute to its immunoinhibitory, however, with expressing intermediate levels of PD-L1, CD40 ligation mDCs would induce efficient immune response.更多还原