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

描述（由申请人提供）：几条证据线，包括我们自己的数据，表明CD8的一部分，p56lck相关蛋白，标记细胞毒性T淋巴细胞（CTL）群体并结合MHC类I （MHC-I）分子的非多态性结构域，与T细胞受体（TCR）在CTL表面形成分子组装。这些组件的形成促进了CTL反应对靶细胞的敏感性和特异性。我们和其他人已经证明，细胞表面的MHC蛋白也集中在簇中，簇的破坏会影响有效地向T细胞呈递肽抗原的能力。我们最近用一种新的工具，半导体纳米颗粒，量子点（QD）模拟MHC簇，控制pMHC复合物的数量，发现QD上的同源和非同源pMHC复合物有效地协同QD/pMHC与活T细胞结合并诱导T细胞反应。我们的工作假设是，细胞表面的免疫受体聚集导致受体分子之间的距离增加，这对于它们在诱导下游受体介导的信号传导中合作的能力至关重要。该假设将通过追求两个特定目标来验证：(i)评估原始和抗原经历的CD8+ T细胞表面的TCR和CD8之间的接近性，并将CD8-TCR聚集程度的变化与CTL反应的敏感性和特异性联系起来；（ii）估计QDs上pMHC复合物之间的分离距离，并与活细胞表面MHC蛋白之间的相应距离进行比较，评估与QDs结合的具有各种生物活性的pMHC之间的距离对QD/pMHC生物传感器诱导T细胞反应效率的影响。我们的实验有望产生足够的实验参数，然后利用这些参数建立综合模型来解释近端信号的触发机制。了解T细胞和靶细胞上的免疫受体之间的分离距离的作用，将使我们在理解控制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机体抗病毒和抗癌防御不可或缺的组成部分，因此，预期从拟议的研究中得到的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，并促进患者抵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.