MECHANISMS OF ANTIGEN INDUCED NONRESPONSIVENESS IN MATURE CD8+ T CELLS

该项目将继续研究导致 外周成熟CD 8 + T细胞的抗原特异性耐受， 关注激活诱导的细胞死亡和非激活诱导的细胞死亡的作用。 响应能力。与CD 4+细胞相比， 在CD 8 + T细胞中了解这些机制。 具体 目标包括：（目标1）。 为了进一步表征激活诱导的 体外CD 8 + T细胞的无反应性和死亡。 实验将 （一）对被调查人的人身安全造成的损害; 对抗原的初始应答后的CD 8 + T细胞取决于 主要共刺激配体的性质（B7与ICAM-1） 和（ii）CD 8应答后死亡和无反应性的平衡 加细胞抗原取决于定量“强度”， 初始信号的持续时间（抗原剂量/持续时间，共刺激 配体密度等）。 (Aim 2）探讨体外细胞毒作用的机制 诱导CD 8 T细胞无反应性和死亡。对B7和 ICAM-1共刺激配体将进一步检查，以确定 Bcl-xL和Bcl-2存活蛋白的表达和作用， CTLA-4在诱导死亡和无反应性中的作用， Fas/Fas-L和TNF-α在凋亡中的作用。 (Aim 3）定义 体内诱导活化诱导的无反应性的要求 以及CD 8 T细胞的死亡。一个收养转移系统已经 建立用于研究CD 8+细胞对TCR的应答 转基因小鼠，允许数量，位置和表型， 所述细胞在体内应答过程中被测定。 目标1和2下体外研究的预测将是 使用具有明确抗原的微球进行体内测试， 共刺激配体组合物作为“人工APC”。 结果 在这个研究成熟的CD 8 + T细胞的项目中获得的结果将 补充在其他项目中获得的信息， 在CD 4+细胞和I类限制性胸腺细胞中存在类似问题。

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.