PROGRAMMED CELL DEATH IN LYMPHOCYTES

我们继续研究程序化细胞的机制 小鼠T细胞受体(TCR)触发的死亡(PCD)途径 功能成熟的T细胞，并定义了三种不同的死亡 小路。第一种是在T杂交瘤中发现的，激活的外周T细胞 细胞，以及来自HIV+捐赠者的血液T细胞，并涉及Fas和Fas 莱兰德。激活通过钙蛋白依赖上调Fas配体 途径，引起由Fas触发的细胞死亡。这条路是 当杂交瘤细胞被钙蛋白特异性基因转染后被阻断 抑制剂卡巴斯丁，以及其他蛋白酶抑制剂。它 在TCR触发的正常的CD4+和CD8+T细胞母细胞中工作， 但并不参与这些细胞的其他凋亡死亡途径。 基于用蛋白水解酶抑制剂阻止细胞死亡，它还运作 当HIV+捐献者的T细胞被超抗原激活时。在这 蛋白水解酶抑制剂阻断TCR诱导的死亡通路 可以允许激活响应，颠倒T辅助功能 上文所述的缺陷。TCR诱导的第二次死亡反应 发生较慢，由肿瘤坏死因子或淋巴毒素介导。我们有 发现激活的T细胞可以在体外死亡，以响应这些 细胞因子，以前被发现只杀死肿瘤细胞。 这种死亡过程是由一种混合的抗体触发的 两种肿瘤坏死因子受体，并被RNA和蛋白质合成所阻断 抑制剂以及细胞因子IL-2和IL-12。第三个TCR- 当严格纯化静息T细胞时发生诱导死亡反应 从血液、淋巴或脾中提取的抗CD3抗体在夜间暴露于 体外培养。这一死亡以前从未见过，因为它被阻止了 通过各种巨噬细胞和T细胞衍生的细胞因子 通常都在现场。这种默认的死亡途径发生在Fas配体中 突变株GLD，且不被抗Fas抗体阻断，提示 一种新的尚未确定的死亡分子途径。这些结果 认为正常的T细胞激活需要生存信号； 除了TCR和TCR，还需要第三个细胞内信号 共刺激作用，尽管它通常是通过IL-2产生的 前两个信号的后果。

We have continued investigating the mechanisms of programmed cell death (PCD) pathway triggered by the T cell receptor (TcR) in functionally mature T cells, and have defined three distinct death pathways. The first is found in T hybridomas, activated peripheral T cells, and blood T cells from HIV+ donors, and involves Fas and Fas Ligand. Activation upregulates Fas Ligand via a calpain-dependent pathway, giving rise to cell death triggered by Fas. This pathway is blocked when hybridomas are transfected by the calpain-specific inhibitor calpastatin, as well as by other protease inhibitors. It operates in normal CD4+ and CD8+ T cell blasts triggered by the TcR, but is not involved in other apoptotic death pathways in these cells. Based on blocking cell death by protease inhibitors, it also operates when T cells from HIV+ donors are activated by superantigen. In this setting blocking this TcR-induced death pathway by protease inhibitors can allow an activation response, reversing the T helper functional deficiency previously described. A second TcR-induced death response occurs more slowly and is mediated by TNF or lymphotoxin. We have found that activated T cell can die in vitro in response to these cytokines, which have previously been found to kill only tumor cells. This death process is triggered by a mixture of antibodies against both TNF receptors, and is blocked by RNA and protein synthesis inhibitors as well as the cytokines IL-2 and IL-12. A third TcR- induced death response occurs when rigorously purified resting T cells from blood, lymph node, or spleen are exposed to anti-CD3 overnight in vitro. This death has not previously been seen because it is blocked by a variety of macrophage- and T cell-derived cytokines which are normally present. This default death pathway occurs in the Fas Ligand mutant strain gld, and is not blocked by anti-Fas antibody, suggesting a new as-yet- undefined molecular pathway of death. These results argue that a survival signal is required for normal T cell activation; this third intracellular signal is required in addition to the TcR and costimulation, although it normally occurs via IL-2 produced as a consequence of the first two signals.