【摘要】 目的:利用北京大学基础医学院免疫学系T细胞室建立的小鼠髓质区CD4单阳性(single positive,SP)胸腺细胞的发育程序,观察超抗原葡萄球菌肠毒素B(staphylococcal enterotoxin B,SEB)对髓质区CD4SP胸腺细胞各亚群的克隆清除情况,从而了解胸腺细胞阴性选择的阶段特异性。方法:从尾静脉注射SEB后,检测小鼠胸腺细胞表面分子的表达及凋亡情况,并根据细胞计数计算髓质区CD4SP胸腺细胞各亚群的减少情况。结果:注射SEB后,胸腺细胞凋亡明显增加,CD4SP细胞数减少显著,约减少了43.8%。进一步分析T细胞受体(T cell receptor,TCR)Vβ8+CD4+细胞后发现,6C10+CD69+Qa-2-的细胞(SP1)的比例减少了近2/3,而Qa-2+的细胞(SP4)比例相对增加。计算TCRVβ8+CD4+细胞各亚群的绝对细胞数,结果发现,SP1、SP2、SP3均减少80%以上,而SP4减少50%左右。结论:胸腺阴性选择发生在SP阶段,并贯穿SP胸腺细胞的整个发育过程,而处于发育成熟阶段的SP4细胞对凋亡较不成熟的SP1~SP3耐受。更多还原

【Abstract】 Objective:To investigate the clonal deletion of medullary CD4SP thymocyte subgroups induced by superantigen SEB,and to understand the stage specificity of thymic negative selection based on the developmental pathway of medullary CD4SP thymocytes we established previously.Methods:SEB was intravenously injected into C57BL/6 mice,and then the expression of surface molecules and apoptosis of thymocytes were detected by FACS.The reduction of each subgroup of medullary CD4SP thymocytes was analyzed by FACS assay and cell counting.Results:The percentage of apoptotic CD4SP thymocytes significantly increased after the intravenous injection of SEB.The cell number of CD4SP decreased about 43.8%.Among TCR Vβ8+CD4SP thymocytes,the percentage of 6C10+CD69+Qa-2-thymocytes(SP1) was reduced by two thirds and the percentage of Qa-2+ thymocytes(SP4) was comparatively increased,while the cell numbers of SP1 to SP3 decreased over 80% and that of SP4 decreased about 50%.Conclusion:Thymic negative selection occurs during the stage of SP and goes through the whole developmental progress from SP1 to SP4.The thymocytes in the stage of SP1 to SP3 are more sensitive to apoptosis than those in the stage of SP4.更多还原