目的探讨肿瘤坏死因子（ＴＮＦ）诱导的Ｕ９３７细胞凋亡与Ｂｃｌ２基因表达的关系。方法首先用ＴＮＦ处理Ｕ９３７细胞，提取小片段ＤＮＡ进行ＤＮＡ断裂分析，并通过ＲＴＰＣＲ检测细胞的Ｂｃｌ２基因ｍＲＮＡ表达；继而以磷酸钙沉淀法将Ｂｃｌ２基因转染到Ｕ９３７细胞，用Ｇ４１８筛选稳定转染子，然后用不同剂量ＴＮＦ处理后观察转染与未转染细胞的存活率。结果ＴＮＦ诱导的Ｕ９３７细胞Ｂｃｌ２基因的ｍＲＮＡ表达下调；用Ｂｃｌ２稳定转染的Ｕ９３７细胞经ＴＮＦ处理，存活率明显高于未转染细胞。结论Ｂｃｌ２基因增强表达阻抑ＴＮＦ诱导的Ｕ９３７细胞凋亡。 Objective To investigate the relationship between apoptosis of U937 cells induced by tumor necrosis factor (TNF) and the expression of Bcl2 gene. Methods U937 cells were first treated with TNF to extract small fragments of DNA for DNA fragmentation analysis. RT-PCR was used to detect the expression of Bcl2 mRNA in the cells. Then, Bcl2 gene was transfected into U937 cells by calcium phosphate precipitation method. Stable transfectants were screened with G418, and the viability of transfected and non-transfected cells was observed after treatment with different doses of TNF. Results The expression of mRNA in Bcl2 gene was down-regulated in TNF-induced U937 cells. The survival rate of U937 cells stably transfected with Bcl2 was significantly higher than that of untransfected U937 cells. Conclusion Bcl2 enhances the expression of Bcl2 gene and inhibits the apoptosis of U937 cells induced by TNF.