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

描述(申请人提供)：包括我们自己的数据在内的几行证据表明，CD8的一部分，即p56lck相关蛋白，标志着一群细胞毒性T淋巴细胞(CTL)，并与MHC-I类分子的非多态结构域结合，与CTL表面的T细胞受体(TCR)形成分子组装。这些组件的形成有助于针对靶细胞的CTL反应的敏感性和特异性。我们和其他人已经证明，细胞表面的MHC蛋白也集中在簇中，簇的破坏会影响向T细胞有效呈递多肽抗原的能力。我们最近用一种新的工具-半导体纳米粒子量子点(QD)模拟了MHC团簇，发现量子点上的同源和非同源pMHC复合体有效地协同作用于QD/pMHC与活T细胞的结合和诱导T细胞反应。我们的工作假设是，免疫受体在细胞表面的聚集导致受体分子之间的接近程度增加，这对于它们在诱导下游受体介导的信号传递方面的合作能力是必不可少的。该假说将通过追求两个特定目标来检验：(I)评估初始和抗原敏感的CD8+T细胞表面TCR和CD8之间的接近程度，并将CD8-TCR聚集的程度的变化与CTL反应的敏感性和特异性联系起来；(Ii)估计附着在量子点上的pMHC复合体之间的分离距离，并将它们与活细胞表面MHC蛋白之间的对应距离进行比较，以及评估与量子点结合的各种生物活性的pMHC之间的接近对这种QD/pMHC生物传感器激发T细胞反应的效率的影响。所提出的实验有望产生足够数量的实验参数，然后可以用来建立全面的模型来解释近端信号的触发机制。了解T细胞和靶细胞上免疫受体之间的距离的作用，将使我们能够在了解控制T细胞激活的分子机制方面取得进展，并最终允许操纵T细胞的各种活动来影响T细胞介导的免疫。公共卫生相关性：由于CD8+细胞毒性淋巴细胞是宿主体内抗病毒和抗癌防御不可缺少的组成部分，因此对其作用机制的更好理解将有助于开发新的策略来提高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.