CD4+ T cell affinity for self and foreign antigens in the CNS

描述(由申请人提供)：到目前为止，我们评估CD4T细胞频率和亲和力的最好工具是多肽：MHC(PMHC)四聚体或功能分析；这两种方法都不能有效地识别所有对特定抗原有反应的细胞。这与CD8 T细胞相反，在CD8 T细胞中，这些技术被证明更准确。一般来说，针对II类抗原的pMHC四聚体很难产生和识别一小部分有反应的CD4T细胞，特别是当抗原来自自身蛋白质时。这是因为四聚体是基于亲和力的，如果亲和力太低，那么四聚体在评估反应功能反应方面的作用有限，也低估了抗原反应性CD4T细胞的数量。例如，在针对髓鞘抗原的反应中，效应性细胞因子反应通常是使用强效药剂如PMA和离子霉素来确定的，它们破坏了T细胞信号级联反应，可能与针对抗原本身产生的细胞因子几乎没有相关性。为了更好地评估CD4T细胞的反应范围，我们已经开始使用基于微管的亲和分析。我们在此报告了针对髓鞘或病毒抗原的CD4T细胞的频率和亲和力的评估方面的重大进展。因此，第一次有可能跟踪疾病进展过程中CD4T细胞反应的亲和力范围。我们的初步发现导致了以下中心假设，即CD4T细胞亲和力分布直接影响中枢神经系统的疾病结局和免疫介导的组织损伤。针对自身抗原、髓鞘少突胶质细胞糖蛋白和病原体相关的淋巴细胞性脉络膜脑膜炎病毒抗原的CD4T细胞，提出了三个特定的目标来验证这一假说。目的1-确定CD4T细胞在慢性自身免疫性疾病和病毒感染过程中的亲和力。目的2-确定T细胞亲和力和效应器表型之间的联系。目的3-确定高亲和力T细胞与低亲和力T细胞对中枢神经系统中发现的抗原的反应。 公共卫生相关性：CD4T细胞在多发性硬化症(MS)等自身免疫反应的发病机制中发挥主要作用，对于正确应对慢性病毒感染至关重要。这笔赠款的总体目标是确定中枢神经系统(CNS)中髓鞘和病毒抗原的T细胞亲和力范围。所提出的研究应用了一种新的方法来评估小鼠EAE和LCMV模型中反应性T细胞反应的亲和力，但我们的结果应该可以迅速应用于患者。因此，我们的发现与人类健康高度相关，并将被证明是评估疾病预后和开发有效治疗方法的宝贵资产。

DESCRIPTION (provided by applicant): To date, our best tools for assessing the frequency and affinity of CD4+ T cells have been peptide:MHC (pMHC) tetramers or functional assays; neither of which effectively identify all of the responding cells to a particular antigen. This is in contrast to CD8+ T cells where these techniques prove more accurate. Generally, pMHC tetramers for class II antigens are difficult to produce and identify a small percentage of responding CD4+ T cells especially when antigen is derived from self proteins. The reason for this is that tetramer is based on affinity and if affinity is too low, then the tetramer is of limited use in assessing the response Functional responses also underestimate the number of antigen reactive CD4+ T cells. In the case of responses directed against myelin antigens for instance, the effector cytokine response is often determined using strong pharmacologic agents such as PMA and ionomycin, which hammer the T cell signaling cascade and may have little relevance to the cytokines being produced in response to antigen itself. To better assess the range of responding CD4+ T cells, we have begun to use micropipette based affinity assay. We report here a major advancement in assessment in the frequency and affinity of CD4+ T cells directed against myelin or viral antigens. Therefore for the first time, it is possible to track the range of affinities of a CD4+ T cells response during disease progression. Our preliminary findings have led to the following central hypothesis that the CD4+ T cell affinity profile directly impacts disease outcome and immune mediated tissue damage in the CNS. Three specific aims are proposed to test this hypothesis focused on CD4+ T cells specific for self antigen myelin oligodendrocyte glycoprotein and pathogen associated lymphocytic choriomeningitis virus antigens. Aim 1- Identify the affinity of CD4+ T cells over the course of chronic autoimmune disease and viral infection. Aim 2- Define the connection between T cell affinity and effector phenotype. Aim 3- Establish the contribution of high versus low affinity T cells in response to antigens found in the CNS. PUBLIC HEALTH RELEVANCE: CD4+ T cells play a major role in the pathogenesis of autoimmune responses such as multiple sclerosis (MS) and are critical for proper response to chronic viral infections. The overall goal of this grant is to define the range of T cell affinities for myelin and viral antigens in the central nervous system (CNS. The proposed studies apply a novel means for assessing the affinity if the responding T cell response in the murine EAE and LCMV models, but our results should be rapidly transferable to patients. Therefore, our findings are highly relevant to human health and will prove to be a valuable asset for assessing disease prognosis and for the development of effective treatments.