Deconstructed T cell antigen recognition: Separation of affinity from bond lifetime

摘要 抗原的识别是触发T细胞存活、扩增、发育和免疫应答所需的第一个关键步骤。 效应器功能和向记忆的过渡。在Evavold和威廉姆斯实验室的一个联合项目中，我们将 确定T细胞受体（TCR）和肽：MHC（pMHC）的亲和力、键寿命和力的大小 定义T细胞表型。因此，拟议的工作是有影响力的，因为它开始界定每个人的作用， 这些参数在与TCR信号强度相关的丰富T细胞生物学中起作用。到目前为止， TCR信号强度通常是考虑到三维SPR亲和力来描述的， 通过代表性的表面标志物、pMHC四聚体和功能读数测量。与这些相反 方法，我们的研究依赖于TCR和pMHC在细胞表面的相互作用的分析 膜使用新的测定，定义了原位二维接触，发生在T细胞和 抗原识别过程中的APC。初步工作发现，键寿命和力的水平， 与亲和力相反，它为表型命运提供了主要驱动力。这三个具体目标将重新定义 TCR信号强度的概念，从键寿命中剖析亲和力，并确定低亲和力的结果 感染期间的TCR。目前，对于许多T细胞，TCR对pMHC的亲和力和结合寿命是未知的。 反应，限制了我们对T细胞介导的反应如何被触发以及亲和力和结合如何被激活的知识。 寿命被转化为TCR信号强度和效应表型。因此，我们的工作将证明 通过解决基于亲和力的预测和实际T细胞功能之间的差异， 结果。

Abstract Recognition of antigen is the first critical step required in triggering T cell survival, expansion, development of effector functions, and transition to memory. In a joint project between the Evavold and Williams labs, we will determine how T cell receptor (TCR) and peptide:MHC (pMHC) affinity, bond lifetimes, and force magnitude define T cell phenotype. The proposed work is therefore impactful as it begins to delineate the role each of these parameters play in the rich T cell biology associated with TCR signal strength. To date, the concept of TCR strength of signal has generally been described with three-dimensional SPR affinity in mind and measured via representative surface markers, pMHC tetramers, and functional readouts. In contrast to these methods, our studies depend on the analysis of TCR and pMHC interactions at the surface of the cell membrane using novel assays that define the in-situ two-dimensional contact that occurs between T cells and APCs during antigen recognition. The preliminary work has discovered that bond lifetime and level of force as opposed to affinity provides the major driving force for phenotypic fate. The three specific aims will redefine the concept of TCR strength of signal, dissect affinity from bond lifetime, and determine outcomes of low affinity TCRs during infection. Currently, the TCR affinity and bond lifetime for pMHC are unknown for many T cell responses, limiting our knowledge on how T cell mediated responses are triggered and how affinity and bond lifetime are translated into TCR strength of signal and effector phenotypes. Therefore, our work will prove insightful by addressing the discrepancy between affinity based predictions and actual T cell functional outcomes.