Tabi Z, McCombe P A, Pender M P
Department of Medicine, University of Queensland, Brisbane, Australia.
Eur J Immunol. 1994 Nov;24(11):2609-17. doi: 10.1002/eji.1830241107.
A CD4+V beta 8.2+ T cell clone specific for the peptide 72-89 of guinea pig myelin basic protein (GMBP) was used to induce acute experimental autoimmune encephalomyelitis (EAE) in Lewis rats. To assess apoptosis in inflammatory cells infiltrating the central nervous system (CNS), we extracted cells from the spinal cord, enriched them for T cells and performed flow-cytometric analysis of their DNA stained with propidium iodide. The presence of apoptosis was confirmed by the demonstration of DNA fragmentation on gel electrophoresis. A gradual increase in the proportion of apoptotic cells was observed between 4 and 7 days after the transfer of the encephalitogenic T cells. The highest frequency of apoptotic cells (9.2 +/- 1.2%) was observed 7 days after cell transfer, when clinical recovery commenced. Passive transfer of ovalbumin-specific cells resulted in only a background level (0.8%) of apoptosis in the CNS. We conclude that the apoptotic process selectively eliminates autoreactive T cells from the CNS as: (a) there was a selective disappearance of disease-relevant CD5+V beta 8.2+ cells from the CNS during the course of EAE; (b) there was a decrease in the frequency of CNS-infiltrating T cells reactive to the GMBP 72-89 peptide during the course of EAE, and in a standard proliferation assay there was a loss of in vitro reactivity of CNS-infiltrating cells to this peptide, but not to a non-CNS antigen (ovalbumin); (c) simultaneous surface labeling and DNA analysis of CNS-infiltrating cells revealed that the frequency of V beta 8.2+ cells was about sevenfold higher in the apoptotic T cell population than in the normal (non-apoptotic) T cell population; and (d) we were unable to detect recirculation of the V beta 8.2+ cells to lymphoid organs after their frequency decreased in the CNS. The selective apoptotic elimination of autoreactive T cells from the target organ of this spontaneously resolving autoimmune disease may have implications for the understanding of the mechanism by which an autoimmune attack is terminated and for the design of therapeutic strategies to facilitate this process.
利用针对豚鼠髓鞘碱性蛋白（GMBP）72 - 89肽段的CD4 + Vβ8.2 + T细胞克隆，在Lewis大鼠中诱导急性实验性自身免疫性脑脊髓炎（EAE）。为了评估浸润中枢神经系统（CNS）的炎性细胞中的细胞凋亡情况，我们从脊髓中提取细胞，富集T细胞，并对用碘化丙啶染色的DNA进行流式细胞术分析。通过凝胶电泳显示DNA片段化来确认细胞凋亡的存在。在致脑炎性T细胞转移后4至7天，观察到凋亡细胞比例逐渐增加。细胞转移7天后，当临床恢复开始时，观察到凋亡细胞的最高频率（9.2±1.2%）。卵清蛋白特异性细胞的被动转移仅导致CNS中背景水平（0.8%）的细胞凋亡。我们得出结论，凋亡过程选择性地从CNS中清除自身反应性T细胞，原因如下：（a）在EAE病程中，与疾病相关的CD5 + Vβ8.2 +细胞从CNS中选择性消失；（b）在EAE病程中，对GMBP 72 - 89肽段有反应的CNS浸润T细胞频率降低，并且在标准增殖试验中，CNS浸润细胞对该肽段的体外反应性丧失，但对非CNS抗原（卵清蛋白）没有丧失；（c）对CNS浸润细胞进行同时的表面标记和DNA分析显示，凋亡T细胞群体中Vβ8.2 +细胞的频率比正常（非凋亡）T细胞群体高约7倍；（d）在CNS中Vβ8.2 +细胞频率降低后我们无法检测到它们再循环至淋巴器官。从这种自发缓解的自身免疫性疾病的靶器官中选择性凋亡清除自身反应性T细胞，可能对理解自身免疫攻击终止的机制以及设计促进该过程的治疗策略具有启示意义。
