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被充分记录。我们实验室和其他实验室最近的研究表明，CTL的功能亲合力（由对肽抗原的敏感性定义）是体内病毒清除功效的主要决定因素。控制单个CTL的亲合力以及体内高亲合力CTL的活化和扩增的机制是免疫学中的基本问题，其对疫苗构建体和免疫治疗剂的设计具有重要意义。目前，在单个T细胞中建立亲合力的机制在很大程度上是不确定的。此外，亲合力是固有性质还是可以响应于环境信号而被调节是未知的。在我们的分析中， 在从TCR转基因小鼠产生的低亲合力系中，我们令人惊讶地观察到低亲合力细胞除了表达CD 8 α/β异源二聚体之外还表达CD 8 α/β同源二聚体。CD 8 α a/α的表达可能降低这些细胞抑制TCR信号的效率，因为CD 8 α/α及其相关激酶Lck对脂筏驻留TCR的定位降低。使用来自TCR转基因小鼠的分选的细胞群，我们发现细胞表面的CD 8 β表达作为肽水平的结果而受到调节。 这与抗原接触调节亲合力的假设一致。在目标一中，我们将解决一些关键问题，包括如何CDSalpha和β表达的抗原遇到调制，当亲合力成为固定在效应细胞，肽抗原的水平如何改变与TCR复合物的CDS的协会，以及记忆细胞是否能够CDS调制的水平提出的肽抗原。α和/或β的进一步表达 将被逆转录病毒转导改变，并将研究CDS蛋白表达以确定CDS表达如何被控制及其对功能的影响。在第二个目标中，我们将我们的差异抗原呈递的影响，在体内激活的CD 8 + T细胞病毒感染后，在体外研究。这将通过使用导致高、中或低水平呈递抗原的一组牛痘病毒来实现。来自这些研究的结果将显著增加对体内功能性亲合力的控制和高亲合力细胞的活化/扩增的理解，并且可以提供新的免疫调节剂。 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.