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

描述（由申请人提供）：迄今为止，我们评估CD 4 + T细胞频率和亲和力的最佳工具是肽：MHC（pMHC）四聚体或功能测定;这两种方法都不能有效鉴定对特定抗原的所有应答细胞。这与CD 8 + T细胞相反，这些技术证明更准确。通常，II类抗原的pMHC四聚体难以产生和鉴定小百分比的应答性CD 4 + T细胞，特别是当抗原来源于自身蛋白时。其原因是四聚体是基于亲和力的，如果亲和力太低，那么四聚体在评估应答中的用途有限。功能性应答也低估了抗原反应性CD 4 + T细胞的数量。例如，在针对髓磷脂抗原的应答的情况下，效应细胞因子应答通常使用强药理学试剂如PMA和离子霉素来确定，其冲击T细胞信号传导级联并且可能与应答抗原本身产生的细胞因子几乎无关。为了更好地评估应答的CD 4 + T细胞的范围，我们已经开始使用基于微量移液管的亲和力测定。我们在此报告了针对髓鞘或病毒抗原的CD 4 + T细胞的频率和亲和力评估的重大进展。因此，第一次有可能跟踪疾病进展期间CD 4 + T细胞应答的亲和力范围。我们的初步发现导致了以下中心假设，即CD 4 + T细胞亲和力谱直接影响CNS中的疾病结果和免疫介导的组织损伤。提出了三个具体的目标，以测试这一假设集中在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脉络丛脑膜炎病毒抗原特异性的CD 4 + T细胞。目的1-确定慢性自身免疫性疾病和病毒感染过程中CD 4 + T细胞的亲和力。目的2-确定T细胞亲和力和效应表型之间的联系。目的3-确定高与低亲和力T细胞对CNS中发现的抗原的反应。 公共卫生相关性：CD 4 + T细胞在自身免疫反应如多发性硬化（MS）的发病机制中起主要作用，并且对于慢性病毒感染的适当反应至关重要。这项资助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。提出的研究应用了一种新的方法来评估亲和力，如果在小鼠EAE和LCMV模型中的响应T细胞反应，但我们的结果应该是迅速转移到患者。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.