中文摘要：

目的：了解FasL／Fas途径参与问号钩端螺旋体（简称钩体）诱导细胞凋亡及其FasL／Fas表达水平变化。方法：建立问号钩体黄疸出血群赖型56601株感染小鼠单核一巨噬细胞J774A．1模型。采用DAPI染色法观察问号钩体56601株感染细胞凋亡的形态学特征，流式细胞术定量检测感染细胞的凋亡率及FasL中和抗体对细胞凋亡的阻断作用。PE标记抗小鼠FasL或Fas单克隆抗体染色法，观察问号钩体56601株感染细胞FasL／Fas表达情况。采用流式细胞术定量检测感染细胞的FasL／Fas表达水平。结果：问号钩体56601株感染J774A．1细胞4h时，部分细胞出现染色质浓缩及边缘化现象；感染24h时上述病变现象更加明显且有部分细胞核裂解。问号钩体56601株感染J774A．1细胞4h和24h的凋亡率分别为53．6％和64．31％。FasL中和抗体预处理细胞后，问号钩体56601株感染细胞4h或24h的凋亡率分别为10．27％和15．90％。J774A．1细胞被问号钩体56601株感染后4和24h，FasL表达率分别从感染前的4．19％上升至21．69％和65．70％，Fas表达率分别从感染前的12．88％上升至91．96％和88．01％。结论：诱导细胞凋亡是问号钩体56601株损伤J774A．1细胞的重要机制。问号钩体可上调靶细胞FasI。／Fas表达水平；并通过FasL／Fas途径诱导J774A．1细胞凋亡。

英文摘要：

Objective： To determine the involvement of FasL/Fas pathway in apoptosis of J774A. 1 cells induced by Leptospira interrogans. Methods： The cell infection model was established with mouse monocyte macrophage J774A. 1 cells infected by L. interrongans serogroup Icterohaemorrhagiae serovar lai strain 56601. The morphological characteristics of apoptotic J774A. 1 cells were observed by DAPI staining method,and the apoptosis rate was quantitatively determined by flow cytometry. FasL neutralizing antibody was applied to block the apoptosis. Expression of FasL or Fas in the L. interrongans strain 56601-infected J774A. 1 cells was detected by flow cytometry using PE-conjugated monoclonal antibody. Results： Chromatin condensation and marginalization were found in J774A. 1 ceils infected by L. interrongans strain 56601 for 4 h, which became more predominant for 24 h and karyorrhexis was present in some cells. When J774A. 1 cells were infected for 4 h and 24 h,the apoptosis rates were 53. 6% and 64. 31%, respectively. However,the apoptosis rates were decreased to 10.27% and 15.9% after the cells were pre-treated with FasL neutralizing antibody. When J774A. 1 cells were infected for 4 h and 24 h,FasL expression rates were increased to 21.69% and 65.70% from that of 4.19% before infection,and Fas expression rates were risen to 91.96% and 88.01% from that of 12.88% before infection. Conclusion： Inducement of cell apoptosis is an important mechanism of L. interrogans strain 56601 injuring J774A. 1 cells. The strain of L. interrogans is able to up-regulate FasL/Fas expression levels of host cells and induce apoptosis of the cells via FasL/Fas pathway.