Immune Receptors on Cytotoxic Lymphocytes and Target Cells

描述（由申请人提供）：颗粒介导的CTL靶细胞裂解的显著敏感性和特异性已得到充分证实，并且被认为是CTL高度选择性和快速破坏病毒感染细胞所必需的。CTL介导的靶细胞破坏的敏感性和功效的潜在机制尚不完全清楚。最近，观察到的不同CTL克隆的靶细胞裂解的敏感性的变化提供了一个机会，调查这些差异的原因，并了解更多关于如何使用支持的脂质双层包含横向移动的单体ICAM-1和肽-MHC（pMHC）模拟靶细胞表面的靶细胞裂解的敏感性控制。我们将研究免疫突触（IS）的形成和模式的颗粒极化和释放的CTL与不同的敏感性的靶细胞裂解。我们还将研究CD 8和CD 4辅助受体在CD 4+和CD 8 + CTL颗粒募集的差异模式中的作用。我们将利用新开发的生物传感器，半导体纳米晶体的基础上，称为量子点（QD），轴承预定数量的紧密间隔的pMHC复合物与各种活动，以模拟MHC聚集在靶细胞膜上，并将评估的pMHC-pMHC接近CTL激活的意义。最后，我们基于病毒学突触（VS）的研究，提出了有关HIV特异性CD 4 + CTL功能的新观点，其中激活的T细胞将gp 120-CD 4相互作用聚集在突触的中央簇中。这些CD 4簇维持Lck的活化，这表明与TCR簇可能的协同作用，其有助于将溶细胞颗粒集中在分泌结构域中。为了验证这一假设，我们将研究gp 120介导的信号传导对暴露于HIV感染细胞的平面双层模型表面的CD 4 + CTL中的细胞溶解颗粒极化和释放模式的影响。同时，我们还将确定gp 120-CD 4相互作用对CD 4 + CTL裂解靶细胞敏感性的影响。该实验有望揭示CTL对HIV感染细胞的敏感性破坏机制，并有望更好地了解CD 4 + CTL在HIV特异性免疫中的作用。进一步了解CTL清除病毒感染细胞的细胞毒性机制将有助于开发新的策略，以提高细胞毒性淋巴细胞的性能，使患者能够更好地对抗HIV感染。 叙述：利用最先进的成像技术，我们将探索病毒特异性细胞毒性T淋巴细胞（CTL）释放颗粒的分子机制，从而有效和快速地破坏病毒感染的细胞。所提出的实验的结果将可能导致开发新的方法，以提高敏感性和特异性的病毒特异性CTL在抗病毒治疗的背景下。

DESCRIPTION (provided by applicant): Remarkable sensitivity and specificity of granule-mediated target cell lysis by CTL is well established and is thought to be necessary for highly selective and rapid destruction of virus-infected cells by CTL. Mechanisms underlying the sensitivity and efficacy of CTL mediated destruction of target cells are not entirely clear. Recently, observed variations in the sensitivity of target cell lysis by different CTL clones offer an opportunity to investigate factors responsible for these differences and to learn more about how the sensitivity of target cell lysis is controlled using supported lipid bilayers containing laterally mobile monomeric ICAM-1 and peptide-MHC (pMHC) to model the surface of target cells. We will examine immunological synapses (IS) formation and patterns of granule polarization and release by CTL with different sensitivity of target cell lysis. We will also examine the role of CD8 and CD4 co-receptors in differential patterns of granule recruitment by CD4+ and CD8+ CTL. We will utilize newly developed biosensors, based on semiconductor nanocrystals, called quantum dots (QD), bearing pre-determined numbers of closely spaced pMHC complexes with various activities to mimic MHC clustering on target cell membranes and will evaluate the significance of the pMHC-pMHC proximity for CTL activation. Finally, we propose a novel view concerning the function of HIV-specific CD4+ CTL based on studies of virological synapse (VS), in which activated T cells cluster gp120-CD4 interactions in a central cluster of the synapse. These CD4 clusters sustain activation of Lck suggesting a possible synergy with TCR clusters that facilitates focusing of cytolytic granules in the secretory domain. To test the hypothesis we will examine the effect of gp120-mediated signaling on pattern of cytolytic granule polarization and release in CD4+ CTL exposed to planar bilayers modeling surface of HIV-infected cells. In parallel, we will also determine the impact of gp120-CD4 interactions of the sensitivity of target cell lysis by CD4+ CTL. The proposed experiments are expected to reveal mechanisms of sensitive destruction of HIV infected cells by CTL and promise to better understand the role of CD4+ CTL in HIV-specific immunity. Further understanding of the mechanisms of cytotoxicity exercised by CTL eradicating virus-infected cells will be instrumental for the development of new strategies to enhance the performance of cytotoxic lymphocytes and to enable patients to better fight HIV infection. Narrative: Using cutting edge imaging technology, we will explore molecular mechanism of granule release by virus-specific cytotoxic T lymphocytes (CTL) accounting for effective and rapid destruction of virus-infected cells. The results of proposed experiments will likely lead to the development of new approaches to enhance sensitivity and specificity of virus-specific CTL in the context of anti-viral therapy.