The World Health Organization has declared SARS-CoV-2 virus outbreak a world-wide pandemic. Individuals infected by the virus exhibited different degrees of symptoms, the basis of which remains largely unclear. Currently, though convalescent individuals have been shown with both cellular and humoral immune responses, there is very limited understanding on the immune responses, especially adaptive immune responses, in patients with severe COVID-19. Here, we examined 10 blood samples from COVID-19 patients with acute respiratory distress syndrome (ARDS). The majority of them (70%) mounted SARS-CoV-2-specific humoral immunity with production of neutralizing antibodies. However, compared to healthy controls, the percentages and absolute numbers of both NK cells and CD8+ T cells were significantly reduced, accompanied with decreased IFNg expression in CD4+ T cells in peripheral blood from severe patients. Most notably, we failed in detecting SARS-CoV-2-specific IFNg production by peripheral blood lymphocytes from these patients. Our work thus indicates that COVID-19 patients with severe symptoms are associated with defective cellular immunity, which not only provides insights on understanding the pathogenesis of COVID-19, but also has implications in developing an effective vaccine to SARS-CoV-2.

中文翻译：

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重症COVID-19患者对SARS-CoV-2的细胞免疫功能受损

世界卫生组织已宣布SARS-CoV-2病毒爆发为全球大流行。被病毒感染的个体表现出不同程度的症状，其基本依据仍不清楚。目前，尽管已显示恢复期的个体同时具有细胞和体液免疫应答，但是对于重症COVID-19的患者的免疫应答，尤其是适应性免疫应答的了解非常有限。在这里，我们检查了COVID-19急性呼吸窘迫综合征（ARDS）患者的10份血液样本。他们中的大多数（70％）通过产生中和抗体来安装SARS-CoV-2特异性体液免疫。但是，与健康对照组相比，NK细胞和CD8 + T细胞的百分比和绝对数量均显着降低，伴随着重症患者外周血CD4 + T细胞中IFNg表达的降低。最值得注意的是，我们未能检测到这些患者外周血淋巴细胞产生的SARS-CoV-2特异性IFNg。因此，我们的工作表明具有严重症状的COVID-19患者与细胞免疫功能低下有关，这不仅为了解COVID-19的发病机理提供了见识，而且对开发针对SARS-CoV-2的有效疫苗也具有重要意义。