Structural Immunology of CD1 and CD1-TCR Complexes

描述(申请人提供)：在过去的10年里，积累了大量的数据，证明了糖脂反应性T细胞在自身免疫性疾病、宿主防御和肿瘤发展中的作用。T细胞和NKT细胞可以对CD1分子呈递的大量自身和外来抗原做出反应，并可以通过细胞毒性T淋巴细胞(CTL)触发对抗原提呈细胞的杀伤，或者通过产生可溶性抗体从体液免疫系统中招募HELP(T辅助细胞)。我们实验室对细胞免疫中脂抗原识别的分子机制很感兴趣。为此，我们通过表面等离子体共振研究(SPR)来确定不同糖脂反应性T细胞受体(TCR)与不同CD1抗原提呈分子的结合动力学。我们将进一步将获得的结果与使用T细胞杂交瘤测量T细胞激活时细胞因子产生的数据相关联。最终，我们建议用X射线结晶学的方法来确定不同脂类和同源T细胞受体(TCR)的复合体中CD1抗原受体的三维结构。我们专门针对以下具体目标：1)人和小鼠硫脂反应性NKT细胞的生化和功能特性是什么。我们将测定硫脂负载的人CD1a和小鼠CD1d与各自的TCR的络合物的结构，并用SPR表征它们的结合动力学。对这两种复合体的比较将提供对免疫系统识别硫脂的相似性和差异性的见解，并将阐明它们激活的分子机制。2)我们将从结构和功能上研究人和小鼠NKT细胞识别伯氏疏螺旋体糖脂的差异。3)我们将研究新型内源性自体脂质与小鼠CD1d的结合及其对NKT细胞的识别作用。对自身和微生物抗原提呈的差异的结构性洞察将有助于理解微生物脂类和脂质反应性T细胞在宿主防御和自身免疫性疾病中的作用。公共卫生相关性：NKT细胞是一种特殊的淋巴细胞，由几个亚型组成，在多发性硬化症等自身免疫性疾病的过程中，可以对来自感染性生物的糖脂产生反应，例如莱姆病的病原体伯氏疏螺旋体和自身脂质。在分子水平上了解这些细胞类型的功能特性对于未来开发抗击这两种疾病的新型化疗药物或佐剂至关重要。

DESCRIPTION (provided by applicant): Over the past 10 years, a tremendous amount of data has accumulated, which demonstrates the role of glycolipid-reactive T cells in autoimmune disease, host defense and tumor development. T cells and NKT cells can respond to a broad pool of self and foreign antigens presented by CD1 molecules and can trigger killing of the antigen presenting cell, through cytotoxic T lymphocytes (CTLs), or recruit help (T helper cells) from the humoral immune system through production of soluble antibodies. Our lab is interested in the molecular mechanisms of lipid antigen recognition in cell-mediated immunity. Toward this goal, we determine the binding kinetics of various glycolipid- reactive T cell receptor's (TCR's) with various CD1 antigen-presenting molecules by surface plasmon resonance studies (SPR). We will further correlate the obtained results with data obtained by measuring cytokine production upon T cell activation using T cell hybridomas. Ultimately we propose to determine the three-dimensional structure of CD1 antigen receptors in complex with different lipids and cognate T cell receptors (TCR's) by x-ray crystallography. We specifically address the following specific aims: 1) What are the biochemical and functional properties of human and mouse sulfatide-reactive NKT cells. We will determine the structure of sulfatide loaded human CD1a and mouse CD1d in complex with the respective TCR and characterize their binding kinetics by SPR. Comparisons of both complexes will provide insights into the similarities and disparities of sulfatide recognition by the immune system and will shed light on the molecular mechanism of their activation. 2) We will structurally and functionally characterize differences in glycolipid recognition of Borrelia burgdorferi glycolipids by human and mouse NKT cells. 3) We will characterize binding of novel endogenous self-lipids to mouse CD1d and their recognition by NKT cells. Structural insights into the differences of self vs. microbial antigen presentation will help understand the role of microbial lipids and lipid-reactive T cells in host defense and autoimmune diseases. Public Health Relevance: NKT cells are specialized lymphocytes that consist of several subtypes and can respond to glycolipids from infectious organisms, such as Borrelia burgdorferi the causative agent of Lyme disease and self-lipids, during the course of autoimmune disease such as Multiple sclerosis. Understanding the functional properties of these cell types at a molecular level is crucial for the future development of novel chemotherapeutic agents or adjuvants to combat both diseases.