MECHANISMS OF ANTIGEN INDUCED NONRESPONSIVENESS IN MATURE CD8+ T CELLS

该项目将继续研究导致 外周成熟CD8+T细胞的抗原特异性耐受性 关注激活诱导细胞死亡和非激活诱导细胞死亡的作用 响应性。与CD4+细胞相比，相对较少的是 已知CD8+T细胞中的这些机制。具体的 目标包括：(目标1)。为了进一步表征激活诱导的 CD8+T细胞体外无能与死亡实验将是 这样做是为了检验两个假设：(I)诱发的无反应性 CD8+T细胞对抗原的初始反应依赖于 主要共刺激配体的性质(B7与ICAM-1) 和(Ii)CD8应答后死亡和无能的平衡 增加细胞对抗原的作用取决于数量上的“强度”和 初始信号的持续时间(抗原剂量/持续时间、共刺激 配基密度等)。(目的2)确定其体外作用机制 诱导CD8T细胞无能和死亡。对B7和 将进一步检查ICAM-1共刺激配体以确定 Bc l-xl和Bc l-2生存蛋白的表达和作用 CTLA-4在诱导死亡和无反应中的作用 Fas/Fas-L和肿瘤坏死因子-α在细胞凋亡死亡中的作用(目标3)定义 活体诱导激活性无能的要求 和CD8T细胞的死亡。一个被采纳的转移系统已经被 建立用于研究TCR中CD8+细胞反应的方法 转基因小鼠允许这样的数量、位置和表型 这些细胞将在体内反应过程中被确定。 根据AIMS 1和AIMS 2进行的体外研究做出的预测将是 使用具有明确定义的抗原的微球进行体内测试 共刺激配体组合物为“人造APC”。结果 在这个研究项目中获得的成熟CD8+T细胞将 补充在其他计划项目审查中获得的结果 在CD4+细胞和I类限制胸腺细胞中也存在类似的问题。

This project will continue studies of the mechanisms that lead to antigen-specific tolerance of mature CD8 plus T cells in the periphery, focusing on the roles of activation-induced cell death and non- responsiveness. In comparison to CD4 plus cells, relatively little is known about these mechanisms in CD8 plus T cells. The Specific Aims include: (Aim 1). To further characterize activation-induced anergy and death in CD8 plus T cells in vitro. Experiments will be done to test two hypothesis: (I) Induction of non-responsiveness in CD8 plus T cells following an initial response to antigen depends upon the nature of the primary costimulatory ligands (B7 versus ICAM-1) and (ii) The balance of death and anergy following response of CD8 plus cells to antigen depends upon the quantitative "strength" and duration of the initial signals (antigen dose/duration, costimulatory ligand density, etc). (Aim 2) To determine the mechanisms of in vitro induction of anergy and death in CD8 T cells. Responses to B7 and ICAM-1 costimulatory ligands will be further examined to determine the expression and roles of Bcl-xL and Bcl-2 survival proteins, the role of CTLA-4 in induction of death and non-responsiveness, and the roles of Fas/Fas-L and TNF-alpha in apoptotic death. (Aim 3) To define the requirements for in vivo induction of activation -induced anergy and death in CD8 T cells. An adoptive transfer system has been established for studying the responses of CD8 plus cells from TCR transgenic mice that allows that number, locations and phenotype of the cells to be determined during the course of an in vivo response. Predictions made by the in vitro studies under Aims 1 and 2 will be tested in vivo using microspheres having well defined antigen and costimulatory ligand compositions as "artificial APCs". Results obtained in this project studying mature CD8 plus T cells will complement those obtained in the other Program projects examining similar issues in CD4 plus cells, and class I restricted thymocytes.