Abstract Global vaccination against COVID-19 has been widely successful; however, there is a need for complementary immunotherapies in severe forms of the disease and in immunocompromised patients. Cytotoxic CD8+ T cells have a crucial role in disease control, but their function can be dysregulated in severe forms of the disease. We report here a cell-based approach using a plasmacytoid dendritic cell line (PDC*line) to expand in vitro specific CD8+ responses against COVID-19 Ags. We tested the immunogenicity of eight HLA-A*02:01 restricted peptides derived from diverse SARS-Cov-2 proteins, selected by bioinformatics analyses in unexposed and convalescent donors. Higher ex vivo frequencies of specific T cells against these peptides were found in convalescent donors compared with unexposed donors, suggesting in situ T cell expansion upon viral infection. The peptide-loaded PDC*line induced robust CD8+ responses with total amplification rates that led up to a 198-fold increase in peptide-specific CD8+ T cell frequencies for a single donor. Of note, six of eight selected peptides provided significant amplifications, all of which were conserved between SARS-CoV variants and derived from the membrane, the spike protein, the nucleoprotein, and the ORF1ab. Amplified and cloned antiviral CD8+ T cells secreted IFN-γ upon peptide-specific activation. Furthermore, specific TCR sequences were identified for two highly immunogenic Ags. Hence, PDC*line represents an efficient platform to identify immunogenic viral targets for future immunotherapies.

中文翻译：

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开发一种现成的基于浆细胞样树突状细胞的新方法，用于 SARS-CoV-2 特异性 T 细胞的扩增和表征

摘要全球针对 COVID-19 的疫苗接种已取得广泛成功；然而，对于严重的疾病和免疫功能低下的患者，需要补充免疫疗法。细胞毒性 CD8+ T 细胞在疾病控制中发挥着至关重要的作用，但其功能在严重的疾病中可能会失调。我们在此报告了一种基于细胞的方法，使用浆细胞样树突状细胞系 (PDC*line) 来扩大针对 COVID-19 Ags 的体外特异性 CD8+ 反应。我们测试了源自不同 SARS-Cov-2 蛋白的 8 种 HLA-A*02:01 限制性肽的免疫原性，这些肽是通过未暴露和恢复期供体的生物信息学分析选择的。与未暴露的供体相比，在恢复期供体中发现针对这些肽的特异性 T 细胞的离体频率更高，这表明病毒感染后 T 细胞原位扩增。负载肽的 PDC* 系诱导了强烈的 CD8+ 反应，总扩增率使单个供体的肽特异性 CD8+ T 细胞频率增加了 198 倍。值得注意的是，八个选定的肽中有六个提供了显着的扩增，所有这些在 SARS-CoV 变体之间都是保守的，并且源自膜、刺突蛋白、核蛋白和 ORF1ab。扩增和克隆的抗病毒 CD8+ T 细胞在肽特异性激活后分泌 IFN-γ。此外，还鉴定出了两种高免疫原性 Ag 的特异性 TCR 序列。因此，PDC*line 代表了一个识别未来免疫疗法的免疫原性病毒靶点的有效平台。