Immune Cell Profiling of COVID-19 Patients in the Recovery Stage by Single-Cell Sequencing

Wen Wen; Wenru Su; Hao Tang; Wenqing Le; Xiaopeng Zhang; Yingfeng Zheng; XiuXing Liu; Lihui Xie; Jianmin Li; Jinguo Ye; Xiuliang Cui; Yushan Miao; Depeng Wang; Jiantao Dong; Chuan-Le Xiao; Wei Chen; Hongyang Wang

The clinical presentation of COVID-19 varies from asymptomatic to severe ARDS. This has been similarly observed in severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV), and influenza infections [12, 14] . In viral infection, it is generally accepted that host immune responses determine both protection against viral infections and the pathogenesis of respiratory injury [18, 19] . A coordinated response in innate and adaptive immune cells working in concert may lead to the rapid control of the virus, whereas a failed immune response might lead to viral spreading, cytokine storm, and a high mortality rate [20] . Despite belonging to same group of viruses, recent studies have highlighted differences between COVID-19, SARS, and MERS, such as the speed of transmission, treatment scheme, and mortality rate. Moreover, this difference may also exist in the key immune players and the underlying molecular mechanisms related to these diseases. The lack of knowledge regarding the immune impact of COVID-19 has now become a critical issue in view of its rapid spread and the shortage of specific therapy [21] . Using single-cell sequencing, we profiled the complexity of immune populations in the blood and analyzed 70,858 cells from 10 patients. We identified a hyper-inflammatory response in ERS patients, which may explain why some patients fell sick after being discharged, and suggest that the current criteria for hospital discharge should be re-evaluated. In addition, we identified unique signatures of myeloid, NKT, and B cells and pinpointed the changes in the epitopes of TCR and BCR.