Coronavirus disease 2019 (COVID-19), caused by infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has a broad clinical presentation ranging from asymptomatic infection to fatal disease. Different features associated with the immune response to SARS-CoV-2, such as hyperinflammation and reduction of peripheral CD8+ T cell counts are strongly associated with severe disease. Here, we confirm the reduction in peripheral CD8+ T cells both in relative and absolute terms and identify T cell apoptosis and migration into inflamed tissues as possible mechanisms driving peripheral T cell lymphopenia. Furthermore, we find evidence of elevated serum interleukin-7, thus indicating systemic T cell paucity and signs of increased T cell proliferation in patients with severe lymphopenia. Following T cell lymphopenia in our pseudo-longitudinal time course, we observed expansion and recovery of poly-specific antiviral T cells, thus arguing for lymphopenia-induced T cell proliferation. In summary, this study suggests that extensive T cell loss and subsequent T cell proliferation are characteristic of severe COVID-19.

中文翻译：

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淋巴细胞减少诱导的T细胞增殖是严重COVID-19的标志

由严重急性呼吸系统综合症冠状病毒2（SARS-CoV-2）感染引起的冠状病毒病2019（COVID-19）具有广泛的临床表现，从无症状感染到致命疾病。与SARS-CoV-2免疫反应相关的不同特征，例如过度炎症和外周CD8 + T细胞计数的减少与严重疾病密切相关。在这里，我们确认了相对和绝对而言，外周CD8 + T细胞的减少，并确定了T细胞凋亡和向发炎组织的迁移是驱动外周T细胞淋巴细胞减少的可能机制。此外，我们发现血清白细胞介素7升高的证据，从而表明系统性T细胞缺乏和严重淋巴细胞减少症患者T细胞增殖增加的迹象。在我们的伪纵向时间过程中出现T细胞淋巴细胞减少症后，我们观察到多特异性抗病毒T细胞的扩增和恢复，因此争论了淋巴细胞减少症诱导的T细胞增殖。总之，这项研究表明严重的COVID-19具有广泛的T细胞丢失和随后的T细胞增殖的特征。