The coronavirus disease 2019 (COVID-19) pandemic poses a current world-wide public health threat. However, little is known about its hallmarks compared to other infectious diseases. Here, we report the single-cell transcriptional landscape of longitudinally collected peripheral blood mononuclear cells (PBMCs) in both COVID-19- and influenza A virus (IAV)-infected patients. We observed increase of plasma cells in both COVID-19 and IAV patients and XIAP associated factor 1 (XAF1)-, tumor necrosis factor (TNF)-, and FAS-induced T cell apoptosis in COVID-19 patients. Further analyses revealed distinct signaling pathways activated in COVID-19 (STAT1 and IRF3) versus IAV (STAT3 and NFκB) patients and substantial differences in the expression of key factors. These factors include relatively increase of interleukin (IL)6R and IL6ST expression in COVID-19 patients but similarly increased IL-6 concentrations compared to IAV patients, supporting the clinical observations of increased proinflammatory cytokines in COVID-19 patients. Thus, we provide the landscape of PBMCs and unveil distinct immune response pathways in COVID-19 and IAV patients.

2019 年冠状病毒病 (COVID-19) 大流行对当前全球公共卫生构成威胁。然而，与其他传染病相比，人们对其特征知之甚少。在这里，我们报告了在 COVID-19 和甲型流感病毒 (IAV) 感染患者中纵向收集的外周血单核细胞 (PBMC) 的单细胞转录情况。我们观察到 COVID-19 和 IAV 患者的浆细胞增加，以及 XIAP 相关因子 1 (XAF1)、肿瘤坏死因子 (TNF) 和 FAS 诱导的 COVID-19 患者 T 细胞凋亡。进一步的分析揭示了 COVID-19（STAT1 和 IRF3）与 IAV（STAT3 和 NFκB）患者中激活的不同信号通路以及关键因子表达的显着差异。这些因素包括 COVID-19 患者中白细胞介素 ( IL ) 6R和IL6ST表达相对增加，但与 IAV 患者相比，IL-6 浓度同样增加，支持了 COVID-19 患者中促炎细胞因子增加的临床观察结果。因此，我们提供了 PBMC 的概况，并揭示了 COVID-19 和 IAV 患者的独特免疫反应途径。