Analysis of MHC Class Ib-Restricted Polyoma Virus-Specific CD8 T Cells

摘要 细胞内病原体的免疫监视主要由传统的TCR？CD8 T介导 识别病原体衍生的寡肽的淋巴细胞，这些寡肽是由高度多态的“经典”或 MHC Ia类分子。然而，越来越多的人认识到，这些寡形化的“非经典”或MHC Ib类分子也可能呈递病原体来源的抗原。然而，迄今为止的证据表明， MHC-Ib限制性CD8 T细胞介导的免疫降级为宿主对细胞内细菌的防御 感染。利用小鼠多瘤病毒(PYV)模型，我们最近发现缺乏MHC类的小鼠 但保留MHC类Ib分子的IA分子(即Kb-/-Db-/-小鼠)与其野生型一样具有抵抗力 相当于这种病毒的致癌潜力，有效地控制了急性和持续性的 感染，并以CD8？T细胞依赖的方式进行。我们鉴定了病毒多肽及其MHC类 IB限制分子，构建MHC-I四聚体试剂，并跟踪进化，功能完整性， 并在PYV感染过程中维持这些新的非常规CD8 T细胞。 重要的是，我们确定这些抗病毒的CD8 T细胞对PYV感染具有保护作用，并且 构成了抗病毒CD8 T细胞谱系中一个以前未被重视的成分。因此，我们的新数据 提供了确定的MHC Ib类限制性抗病毒CD8 T细胞反应的第一个证据，该反应有助于 来主持防守。这个应用程序的总体目标是使用小鼠PYV感染系统来 全面定义诱导这些非常规CD8 T细胞的要求，并应用洞察力 从这些研究中评估促进抗病毒CD8 T细胞招募的候选干预措施 MHC Ia类同种异体屏障。提出了三个具体目标：(1)确定以下要求 PYV特异性MHC Ib类限制性CD8 T细胞的筛选和维持；(2)研究 机制(S)解释了大多数这些T细胞功能受损的发现；以及(3) 确定CD4T细胞在生成和维持过程中的作用并选择共刺激途径 功能性抗PYV MHC Ib类限制性CD8T细胞促进小鼠PYV感染的控制 MHC-Ia同种异体菌株。

ABSTRACT Immunosurveillance for intracellular pathogens is primarily mediated by conventional TCR¿¿ CD8 T lymphocytes that recognize pathogen-derived oligopeptides presented by the highly polymorphic "classical" or MHC class Ia molecules. Yet, there is growing appreciation that these oligomorphic "nonclassical" or MHC class Ib molecules may also present pathogen-derived antigens. Evidence to date, however, has suggested that MHC-Ib-restricted CD8 T cell-mediated immunity is relegated to host defense against intracellular bacterial infections. Using the mouse polyoma virus (PyV) model, we recently discovered that mice lacking MHC class Ia molecules but retaining MHC class Ib molecules (i.e., Kb-/-Db-/- mice) are as resistant as their wild type counterparts to the oncogeneic potential of this virus, efficiently control acute and persistent phases of infection, and do so in a CD8¿¿ T cell-dependent manner. We identified the viral peptide and its MHC class Ib-restricting molecule, constructed MHC-I tetrameric reagents, and tracked the evolution, functional integrity, and maintenance of these novel unconventional CD8 T cells throughout the course of PyV infection. Importantly, we determined that these antiviral CD8 T cells confer protection against PyV infection, and constitute a previously unappreciated component of the antiviral CD8 T cell repertoire. Our new data thus provides the first evidence for a defined MHC class Ib-restricted antiviral CD8 T cell response that contributes to host defense. The overall goal of this application is to use the mouse PyV infection system to comprehensively define the requirements for eliciting these unconventional CD8 T cells, and to apply insights from these studies to evaluate candidate interventions to promote recruitment of antiviral CD8 T cells across MHC class Ia allogeneic barriers. Three Specific Aims are proposed: (1) to define the requirements for selection and maintenance of PyV-specific, MHC class Ib-restricted CD8 T cells; (2) to investigate mechanism(s) to explain the finding that the majority of these T cells are functionally compromised; and (3) to define the contributions of CD4 T cells and select costimulatory pathways in generating and maintaining functional anti-PyV MHC class Ib-restricted CD8 T cells in order to promote control of PyV infection in mice of MHC-Ia allogeneic strains.