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

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对 特定的抗原。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，针对第二类抗原的pMHC四聚体很难产生并鉴定出一小部分 应答CD4T细胞，尤其是当抗原来自自身蛋白质时。这样做的原因是 四聚体是以亲和力为基础的，如果亲和力太低，那么四聚体在评估 反应功能反应也低估了抗原反应性CD4T细胞的数量。在这种情况下 例如，在针对髓鞘抗原的反应中，效应细胞因子反应通常是确定的 使用强药理药物，如PMA和离子霉素，它们锤击T细胞信号级联反应 而且可能与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 对于应答的CD4T细胞的范围，我们已经开始使用基于微管的亲和分析。我们报道 在评估针对髓鞘的CD4T细胞的频率和亲和力方面的主要进展 或病毒抗原。因此，第一次有可能跟踪CD4T细胞的亲和力范围 在疾病发展过程中的反应。我们的初步发现导致了以下中心假设 CD4T细胞亲和力分布直接影响疾病转归和免疫介导的组织损伤 中枢神经系统。提出了三个具体目标来检验这一假设，该假说侧重于自身特有的CD4T细胞 髓鞘少突胶质细胞糖蛋白抗原与病原体相关的淋巴细胞性脉络膜脑膜炎病毒 抗原。 目的1-确定慢性自身免疫性疾病和病毒病程中CD4T细胞的亲和力 感染。 目的2-确定T细胞亲和力和效应器表型之间的联系。 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。

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.