Proximity between immune receptors on the cell surface and the sensitivity of Tce

描述（由申请人提供）：包括我们自己的数据在内的几条证据表明，一部分CD 8，p56 lck相关蛋白，标记细胞毒性T淋巴细胞（CTL）群体并与MHC I类（MHC-I）分子的非多态性结构域结合，与CTL表面上的T细胞受体（TCR）形成分子组装体。这些组装体的形成促进了针对靶细胞的CTL应答的敏感性和特异性。我们和其他人已经表明，细胞表面上的MHC蛋白也集中在簇中，并且簇的破坏影响有效地将肽抗原呈递给T细胞的能力。我们最近用一种新的工具，半导体纳米颗粒，量子点（QD），承载控制数量的pMHC复合物模拟MHC簇，并发现QD上的同源和非同源pMHC复合物有效地合作QD/pMHC与活T细胞的结合和T细胞应答的诱导。我们的工作假设是，细胞表面上的免疫受体的聚集导致受体分子之间的接近度增加，这对于它们在下游受体介导的信号传导的诱导中合作的能力是必不可少的。（i）评估初始和抗原经历的CD 8 + T细胞表面上TCR和CD 8之间的接近性，并将CD 8-TCR聚集程度的变化与CTL应答的敏感性和特异性联系起来;（二）为了估计连接到QD的pMHC复合物之间的分离距离，并将它们与上的MHC蛋白之间的相应距离进行比较，活细胞的表面，并评估与QD结合的具有各种生物活性的pMHC之间的接近性对这种QD/pMHC生物传感器引发T细胞应答的效率的影响。所提出的实验预计将产生足够数量的实验参数，然后可以用于建立全面的模型来解释触发的近端信号的机制。理解T细胞和靶细胞上的免疫受体之间的分离距离的作用应该使我们能够在理解控制T细胞活化的分子机制方面取得进展，并最终允许操纵各种T细胞活性以影响T细胞介导的免疫。公共卫生相关性：由于CD 8+细胞毒性淋巴细胞是宿主机体抗病毒和抗癌防御的不可或缺的组分，因此，更好地理解其作用机制（预计将从所提出的研究中出现）将有助于开发新的策略以增强这些淋巴细胞的性能并促进患者对抗病毒感染和癌症的能力。

DESCRIPTION (provided by applicant): Several lines of evidence, including our own data, suggest that a fraction of CD8, p56lck- associated protein that marks a population of cytotoxic T lymphocytes (CTL) and binds to the nonpolymorphic domain of MHC class I (MHC-I) molecules, form molecular assemblies with T-cell receptor (TCR) on the CTL surface. The formation of these assemblies facilitates the sensitivity and the specificity of CTL responses against target cells. We and others have shown that MHC proteins on the cell surface are also concentrated in clusters and that disruption of the clusters affects the ability to effectively present peptide antigens to T cells. We have recently simulated MHC clusters with a novel tool, semiconductor nanoparticles, quantum dots (QD), bearing controlled numbers of pMHC complexes, and found that the cognate and non-cognate pMHC complexes on QDs effectively cooperate in the binding of QD/pMHC to live T cells and in the induction of T cell responses. Our working hypothesis is that clustering of immune receptors on the cell surface leads to increased proximity between the receptor molecules that are essential for their ability to cooperate in the induction of downstream receptor-mediated signaling. The hypothesis will be tested by pursuing 2 specific aims: (i) To evaluate the proximity between TCR and CD8 on the surface of naive and antigen experienced CD8+ T cells and to relate changes in the extent of CD8-TCR clustering to the sensitivity and specificity of CTL responses; (ii) To estimate the separation distances between pMHC complexes attached to QDs and to compare them with corresponding distances between MHC proteins on the surface of living cells and to evaluate the impact of the proximity between pMHC with various biological activities bound to QDs on the efficiency of such QD/pMHC biosensors to elicit T cell responses. The proposed experiments are expected to generate sufficient amount of experimental parameters, which then can be utilized for building comprehensive models to explain mechanisms of triggering of the proximal signaling. Understanding the role of separating distances between immune receptors on T cells and target cells should enable us to make progress in understanding molecular mechanisms controlling T cell activation and will ultimately permit manipulation of various T cell activities to influence T cell-mediated immunity. Public Health Relevance: Inasmuch as CD8+ cytotoxic lymphocytes are indispensable component of anti- virus and anti-cancer defense of the host body, bettering understanding of the mechanisms of their actions, which is expected to emerge from the proposed research, will facilitate the development of new strategies to enhance the performance of these lymphocytes and to facilitate the ability of patients to fight viral infections and cancer.