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 CD4 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；两者都不能有效识别对特定抗原的所有反应细胞。这与 CD8 T 细胞形成鲜明对比，后者的这些技术被证明更准确。一般来说，II 类抗原的 pMHC 四聚体很难产生和识别一小部分响应的 CD4 T 细胞，特别是当抗原衍生自自身蛋白时。其原因是四聚体基于亲和力，如果亲和力太低，则四聚体在评估反应中的用途有限。功能性反应也会低估抗原反应性 CD4 T 细胞的数量。例如，在针对髓磷脂抗原的反应的情况下，效应细胞因子反应通常是使用强效药物制剂（例如 PMA 和离子霉素）来确定的，这些药物会影响 T 细胞信号级联，并且可能与响应抗原本身而产生的细胞因子几乎没有关系。为了更好地评估响应 CD4 T 细胞的范围，我们已开始使用基于微量移液器的亲和力测定。我们在此报告在针对髓磷脂或病毒抗原的 CD4 T 细胞的频率和亲和力评估方面取得的重大进展。因此，首次有可能追踪疾病进展过程中 CD4 T 细胞反应的亲和力范围。我们的初步研究结果得出以下中心假设：CD4 T 细胞亲和力谱直接影响中枢神经系统的疾病结果和免疫介导的组织损伤。提出了三个具体目标来检验这一假设，重点是对自身抗原髓磷脂少突胶质细胞糖蛋白和病原体相关淋巴细胞脉络膜脑膜炎病毒抗原具有特异性的 CD4 T 细胞。目标 1 - 确定 CD4 T 细胞在慢性自身免疫性疾病和病毒感染过程中的亲和力。目标 2 - 定义 T 细胞亲和力与效应表型之间的联系。目标 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的贡献。 公共卫生相关性：CD4 T 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着重要作用，对于正确应对慢性病毒感染至关重要。这项资助的总体目标是确定中枢神经系统 (CNS) 中髓鞘质和病毒抗原的 T 细胞亲和力范围。拟议的研究应用了一种新方法来评估小鼠 EAE 和 LCMV 模型中响应 T 细胞反应的亲和力，但我们的结果应该可以快速转移到患者身上。因此，我们的研究结果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.