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目的 :探讨重症肌无力 (MG)胸腺细胞凋亡异常、Fas表达异常在自身免疫应答形成中的作用。方法 :用手术切除的MG患者的胸腺 ,制备胸腺提取液和胸腺细胞悬液 ,用MTT比色法测定胸腺细胞的增殖 ;用DNA电泳及细胞形态学观察细胞凋亡 ;用流式细胞仪检测细胞表面Fas的表达 ,用RT PCR结合单链多态构象性分析 (SSCP) ,探讨Fas基因的转录及可能存在的Fas基因突变。结果 :MG患者的胸腺提取液 ,能抑制正常胸腺细胞增殖 ,但不能抑制MG患者胸腺细胞增殖。在地塞米松作用下 ,正常人及患者胸腺细胞的增殖均可被抑制 ,细胞增殖抑制率分别为 5 8.33%和 5 4 .2 6 %。MG患者胸腺细胞的DNA电泳可见梯状条带 ,并且胸腺细胞上Fas的表达百分率增加 [(2 0 .38± 6 .0 7) % ],与空白对照组 [(12 .4 3±4 .32 ) % ]相比较P <0 .0 5。对MG患者胸腺细胞FasmRNA进行RT PCR SSCP分析 ,部分MG患者出现异常电泳条带。结论 :MG患者胸腺细胞的凋亡及Fas分子表达均异常 ,而且存在Fas基因突变 ,提示与本病的发生发展有关。
Objective: To investigate the abnormal apoptosis of myasthenia gravis (MG) and the abnormal expression of Fas in the formation of autoimmune response. Methods: Thymus of thymic gland and thymus cell suspension were prepared by surgical excision. Thymocyte proliferation was measured by MTT colorimetric assay. Cell apoptosis was detected by DNA electrophoresis and cell morphology. Flow cytometry The expression of Fas on the cell surface was investigated by RT PCR combined with single strand polymorphism (SSCP) to investigate the transcription of Fas gene and possible Fas gene mutation. Results: Thymus extract of MG patients can inhibit normal thymocyte proliferation, but can not inhibit the proliferation of thymocytes in MG patients. Under the action of dexamethasone, the proliferation of thymocytes in both normal and patient can be inhibited, and the inhibition rates of cell proliferation were 5 8.33% and 54.26% respectively. The DNA ladder of MG patients’ thymocytes showed ladder-like bands, and the percentage of Fas expression in thymocytes increased ([20.38 ± 6.77]%], compared with that in the blank control group [(12.3 ± 4) 32)%] compared P <0. RT PCR SSCP analysis of Fas mRNA in MG patients showed abnormal electrophoresis bands in some MG patients. Conclusion: The apoptosis of thymus cells and the expression of Fas molecules in patients with MG are abnormal, and the mutation of Fas gene exists, suggesting that it is related to the occurrence and development of this disease.