Department of Medicine II, University Hospital Freiburg, Freiburg, Germany Faculty of Biology, University of Freiburg, Freiburg, Germany.
Department of Medicine II, University Hospital Freiburg, Freiburg, Germany Faculty of Biology, University of Freiburg, Freiburg, Germany Spemann Graduate School of Biology and Medicine, University of Freiburg, Freiburg, Germany.
J Virol. 2015 Jan;89(1):25-34. doi: 10.1128/JVI.02242-14. Epub 2014 Oct 15.
Virus-specific CD8(+) T cells are rarely detectable ex vivo by conventional methods during chronic hepatitis C virus (HCV) infection. In this study, however, we were able to detect and characterize HCV-specific CD8(+) T cells in all chronically HCV genotype 1a-infected, HLA-A*02:01-positive patients analyzed by performing major histocompatibility complex (MHC) class I tetramer enrichment. Two-thirds of these enriched HCV-specific CD8(+) T-cell populations displayed an effector memory phenotype, whereas, surprisingly, one-third displayed a naive-like phenotype despite ongoing viral replication. CD8(+) T cells with an effector memory phenotype could not expand in vitro, suggesting exhaustion of these cells. Interestingly, some of the naive-like CD8(+) T cells proliferated vigorously upon in vitro priming, whereas others did not. These differences were linked to the corresponding viral sequences in the respective patients. Indeed, naive-like CD8(+) T cells from patients with the consensus sequence in the corresponding T-cell epitope did not expand in vitro. In contrast, in patients displaying sequence variations, we were able to induce HCV-specific CD8(+) T-cell proliferation, which may indicate infection with a variant virus. Collectively, these data reveal the presence of phenotypically and functionally diverse HCV-specific CD8(+) T cells at very low frequencies that are detectable in all chronically infected patients despite viral persistence.
In this study, we analyzed CD8(+) T-cell responses specific for HLA-A*02:01-restricted epitopes in chronically HCV-infected patients, using MHC class I tetramer enrichment. Importantly, we could detect HCV-specific CD8(+) T-cell populations in all patients. To further characterize these HCV-specific CD8(+) T-cell populations that are not detectable using conventional techniques, we performed phenotypic, functional, and viral sequence analyses. These data revealed different mechanisms for CD8(+) T-cell failure in HCV infection, including T-cell exhaustion, viral escape, and functional impairment of naive-like HCV-specific CD8(+) T cells.
在慢性丙型肝炎病毒（HCV）感染期间，传统方法很少能在体外检测到病毒特异性 CD8(+) T 细胞。然而，在这项研究中，我们通过进行主要组织相容性复合体（MHC）I 类四聚体富集，能够在所有分析的慢性 HCV 基因型 1a 感染、HLA-A*02:01 阳性的患者中检测和表征 HCV 特异性 CD8(+) T 细胞。这些富集的 HCV 特异性 CD8(+) T 细胞群体中，有三分之二表现出效应记忆表型，而令人惊讶的是，尽管存在持续的病毒复制，但仍有三分之一表现出类似幼稚的表型。具有效应记忆表型的 CD8(+) T 细胞不能在体外扩增，这表明这些细胞已经衰竭。有趣的是，一些类似幼稚的 CD8(+) T 细胞在体外初始刺激后能够大量增殖，而另一些则不能。这些差异与患者相应的病毒序列有关。事实上，在相应 T 细胞表位的共有序列的患者中，类似幼稚的 CD8(+) T 细胞不能在体外扩增。相比之下，在显示序列变异的患者中，我们能够诱导 HCV 特异性 CD8(+) T 细胞增殖，这可能表明感染了变异病毒。总的来说，这些数据揭示了在所有慢性感染患者中，尽管存在病毒持续存在，但仍以非常低的频率存在表型和功能多样化的 HCV 特异性 CD8(+) T 细胞。
在这项研究中，我们使用 MHC I 类四聚体富集分析了慢性 HCV 感染患者中 HLA-A*02:01 限制性表位的 CD8(+) T 细胞反应。重要的是，我们能够在所有患者中检测到 HCV 特异性 CD8(+) T 细胞群体。为了进一步表征这些使用传统技术无法检测到的 HCV 特异性 CD8(+) T 细胞群体，我们进行了表型、功能和病毒序列分析。这些数据揭示了 HCV 感染中 CD8(+) T 细胞衰竭的不同机制，包括 T 细胞衰竭、病毒逃逸和幼稚样 HCV 特异性 CD8(+) T 细胞的功能障碍。
