中文摘要：

目的：探讨大肠杆菌（E.coli）感染与人巨噬细胞系U937细胞凋亡的关系.方法：以Annexin V FITC/PI双染流式细胞仪检测及Hoechst 33258荧光染色,Giemsa染色等细胞形态学观察为指标,研究E.coli感染对U937细胞凋亡的诱导作用.结果：Giemsa染色：E.coli感染10,20 min（U937：E.coli=1：20）后偶见细胞凋亡,感染30,60及90min时可见许多细胞有典型的凋亡形态学改变,并可见凋亡小体;Annexin V FITC/PI双染可见U937细胞凋亡百分率随E.coli感染时间的延长而增高.感染30,60及90min时,细胞凋亡率与对照组相比明显增高,有显著性差异（P＜0.001）.Hoechst 33258荧光染色结果表明当细胞与细菌浓度比较低时（1：10）即可引起部分U937细胞发生凋亡,U937细胞凋亡百分率随E.coli感染剂量的增加而增加,且Hoechst 33258荧光染色及流式细胞仪二种方法所得结果一致.结论：E.coli以时间和剂量依赖方式诱导U937细胞凋亡.

英文摘要：

Objective： To study the relationship between Escherichia coli （ E. coli ） infection and cell apoptosis of human macrophage cell line U937. Methods： The U937 apoptosis induced by E. coli infection was detected with Annexin V FITC/PI assay, Hoechst 33258 fluorochrome staining, and Giemsa staining. Results： Giemsa staining showed that few apoptotic U937 cells were found 10 and 20 minutes after E. coli infection （ U937 ： E. coli = 1 ： 20） , and U937 cells underwent typical apoptotic changes including karyopyknosis, condensation, swelling, and apoptotic bodies 30, 60 and 90 minutes later. Annexin V FITC/PI assay showed that the percentage of apoptotic U937 cells increased with the progression of the E. coli infection. Hoechst 33258 fluorochrome staining and Annexin VFITC/PI assay showed that the percentage of apoptotic U937 ceils increased with the concentrations of E. coli. Conclusion： E. coli could induce U937 apoptosis in a dose-and time-dependent manner.