Immune receptors on Cytotoxic Lymphocytes& Target Cell

细胞毒性淋巴细胞上的免疫受体

• 批准号: 6908215
• 负责人: Yuri Sykulev
• 金额: $ 33.55万
• 依托单位: THOMAS JEFFERSON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6908215
• 关键词: MHC class I antigen; T cell receptor; biological signal transduction; cell adhesion molecules; cell cell interaction; cell membrane; cellular immunity; clinical research; cytokine receptors; cytolysis; cytoskeletal proteins; cytotoxic T lymphocyte; gap junctions; granule; helper T lymphocyte; human tissue; interleukin 2; leukocyte adhesion molecules; natural killer cells

DESCRIPTION (provided by applicant):Although natural abundance of antigenic peptides in some virus-infected is very low, these cells are still lysed by virus-specific cytotoxic T lymphocytes (CTL). We have found that less then a dozen cognate peptide-MHC (pMHC) complexes on target cells are sufficient to render them susceptible for specific lysis by CTL. The molecular mechanism accounting for the striking sensitivity of target cell lysis by CTL is not understood. Our preliminary data suggest that release of a small amount of cytolytic granules would not induce target cell lysis unless the granules are concentrated in a limited space between CTL and target cell membranes. We hypothesized that immunological synapse concentrates the granules preserving their activity at the precise location and accounts for the sensitivity and specificity of target cell lysis by CTL. We have also found that LFA- 1 -1CAM- 1 interactions are sufficient for early stages of immunological synapse formation by CTL. This let us to propose that signaling through adhesion molecules results in the formation of transient synapse that has two typical domains or supramolecular activation clusters (SMACs). The transient synapse is likely to facilitate effective scanning of the surface of target cells by CTL. Most recently, we have found that MHC-I and ICAM-1 molecules are co-localized biochemically and by imaging within membrane rafts. We also showed that raft integrity facilitates viral peptide-MHC (pMHC) detection by CTL through mechanisms that require interaction of LFA-1 and ICAM-1. Based on this we hypothesized that ICAM-1-MHC-I co- clustering in rafts provides the linkage between early immunological synapse formation on CTL and the presentation of antigen on target cells. We further hypothesize that MHC-I and ICAM-1 are recruited to the rafts through adapter proteins to form complex molecular assemblies, which might have distinct structures on various cell types. Using precise manipulation of human CTL clones with known specificity, we will test this hypothesis by pursuing 3 specific aims: (i) To determine the significance of cytolytic molecule concentration by the immunological synapses by studying cytolytic granule release at the interface between the T cell and target cell membranes and the role of LFA-1-ICAM-1 interactions that lead to the synapse formation and effective target cell lysis by CTL; (ii) To determine the mechanism of immunological synapse formation by CTL and NK cells studying adhesion molecule patterns and functional correlates of these patterns; (iii) To determine the functional importance and mechanism of MHC-I and ICAM-1 interactions in membrane rafts.

描述（申请人提供）：虽然一些病毒感染的抗原肽的自然丰度非常低，但这些细胞仍然会被病毒特异性细胞毒性T淋巴细胞（CTL）裂解。我们发现靶细胞上只有不到十几个同源肽-MHC (pMHC) 复合物就足以使它们对 CTL 的特异性裂解敏感。 CTL 裂解靶细胞具有惊人敏感性的分子机制尚不清楚。我们的初步数据表明，少量细胞溶解颗粒的释放不会诱导靶细胞裂解，除非颗粒集中在 CTL 和靶细胞膜之间的有限空间中。我们假设免疫突触将颗粒集中在精确的位置，保留其活性，并解释了 CTL 裂解靶细胞的敏感性和特异性。我们还发现，LFA-1 -1CAM-1 相互作用足以满足 CTL 免疫突触形成的早期阶段。这让我们提出，通过粘附分子的信号传导导致瞬时突触的形成，该突触具有两个典型的结构域或超分子激活簇（SMAC）。瞬时突触可能有助于 CTL 对靶细胞表面的有效扫描。最近，我们通过膜筏内成像发现 MHC-I 和 ICAM-1 分子在生物化学上共定位。我们还表明，筏完整性通过需要 LFA-1 和 ICAM-1 相互作用的机制促进 CTL 检测病毒肽-MHC (pMHC)。基于此，我们假设筏中的 ICAM-1-MHC-I 共聚提供了 CTL 上早期免疫突触形成与靶细胞上抗原呈递之间的联系。我们进一步假设 MHC-I 和 ICAM-1 通过衔接蛋白被招募到筏上，形成复杂的分子组件，这些组件可能在各种细胞类型上具有不同的结构。使用具有已知特异性的人类 CTL 克隆的精确操作，我们将通过追求 3 个具体目标来检验这一假设：（i）通过研究 T 细胞和靶细胞膜之间界面处的溶细胞颗粒释放以及导致突触形成和 CTL 有效靶细胞裂解的 LFA-1-ICAM-1 相互作用的作用，确定免疫突触溶细胞分子浓度的重要性； (ii) 通过研究粘附分子模式和这些模式的功能相关性，确定 CTL 和 NK 细胞形成免疫突触的机制； (iii) 确定膜筏中 MHC-I 和 ICAM-1 相互作用的功能重要性和机制。