Control of cytotoxic T cell differentiation and activity

CDS细胞毒性T淋巴细胞(CTL)对根除病毒感染的贡献已经得到了很好的证明。我们实验室和其他实验室最近的研究表明，CTL的功能亲和力是体内病毒清除效率的主要决定因素，它由对多肽抗原的敏感性定义。控制单个CTL亲和力的机制，以及体内高亲和力CTL的激活和扩增，是免疫学中的基本问题，对疫苗结构和免疫治疗的设计具有重要意义。目前，亲和力在单个T细胞中建立的机制在很大程度上是不确定的。此外，亲和力是一种固有属性，还是可以根据环境信号进行调节，目前尚不清楚。在我们对高和高的分析 对于TCR转基因小鼠产生的低亲和力细胞系，我们进行了令人惊讶的观察，发现低亲和力细胞除了表达CD8α/β异二聚体外，还表达CD8α/β同源二聚体。CD8α/α的表达可能会降低这些细胞转导TCR信号的效率，因为CD8α/α及其相关的激酶Lck对脂筏驻留的TCR的定位减少。利用TCR转基因小鼠的分选细胞群，我们发现CD8P在细胞表面的表达受到多肽水平的调节 抗原相遇，符合亲和力受抗原相遇调节的假说。在第一个目标中，我们将解决一些关于亲和力控制的关键问题，包括CDSalpha和β的表达是如何被抗原相遇调节的，当亲和力在效应细胞中变得固定时，多肽抗原的水平如何改变CDS与TCR复合体的联系，以及记忆细胞是否能够对呈现的多肽抗原水平做出反应来调节CDS。α和/或β的进一步表达 将通过逆转录病毒转导改变CDS蛋白的表达，以确定CDS的表达如何控制及其对功能的影响。在第二个目标中，我们将扩大我们的体外研究，即差异抗原提呈对病毒感染后体内CD8+T细胞激活的影响。这将通过使用一组痘苗病毒来实现，这些病毒会导致高、中或低水平的呈递抗原。这些研究的结果将显著增加对体内功能亲和力的控制和高亲和力细胞的激活/扩张的理解，并可能提供新的 对改进疫苗策略设计的见解。

The contribution of CDS cytotoxic T lymphocytes (CTL) to the eradication of viral infections has been well documented. Recent studies from our lab and others have demonstrated that the functional avidity of a CTL, as defined by the sensitivity to peptide antigen, is a major determinant of the efficacy for viral clearance in vivo. The mechanisms which control the avidity of an individual CTL, as well as the activation and expansion of high avidity CTL in vivo, are fundamental issues in immunology which have important implications for the design of vaccine constructs and immunotherapeutics. Presently, the mechanism by which avidity is established in an individual T cell is largely undefined. Further whether avidity is an inherent property or can be modulated in response to environmental signals is unknown. In our analysis of high and low avidity lines generated from TCR transgenic mice, we made the surprising observation that low avidity cells express CD8alpha/beta homodimers in addition to CD8alpha/beta heterodimers. Expression of CD8alphaa/alpha may reduce the efficiency with which these cells transduce TCR signals, given the reduced localization of CD8alpha/alpha and its associated kinase, Lck, to lipid raft resident TCR. Using sorted populations of cells from TCR transgenic mice, we have found that CD8P expression at the cell surface is regulated as a result of the level of peptide antigen encountered, consistent with the hypothesis that avidity in modulated by antigen encounter. In aim one we will address a number of critical questions regarding the control of avidity including how CDSalpha and beta expression are modulated by antigen encounter, when avidity becomes fixed in effector cells, how the level of peptide antigen alters the association of CDS with the TCR complex, and whether memory cells are capable of CDS modulation in response to the level of presented peptide antigen. Further expression of alpha and/or beta will be altered by retroviral transduction and CDS protein expression will be studied to determine how CDS expression is controlled and its result on function. In aim two we will extend our in vitro studies of the effect of differential antigen presentation to the in vivo activation of CD8+ T cells following viral infection. This will be accomplished through use of a panel of vaccinia viruses which result in high, intermediate, or low levels of presented antigen. The results from these studies will significantly increase of understanding of the control of functional avidity and the activation/expansion of high avidity cells in vivo and may provide novel insights into the design of improved vaccine strategies.