Reduction and Functional Exhaustion of T Cells in Patients With Coronavirus Disease 2019 (COVID-19)

• Published in: Frontiers in immunology Vol. 11; p. 827
• Main Authors: Diao, Bo, Wang, Chenhui, Tan, Yingjun, Chen, Xiewan, Liu, Ying, Ning, Lifen, Chen, Li, Li, Min, Liu, Yueping, Wang, Gang, Yuan, Zilin, Feng, Zeqing, Zhang, Yi, Wu, Yuzhang, Chen, Yongwen
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 01.05.2020
• Subjects: Betacoronavirus - physiology; Coronavirus Infections - blood; Coronavirus Infections - immunology; Coronavirus Infections - pathology; COVID-19; cytokine strom; Cytokines - blood; Humans; Immunology; Lymphocyte Count; Pandemics; Pneumonia, Viral - blood; Pneumonia, Viral - immunology; Pneumonia, Viral - pathology; SARS- CoV-2; T cell exhaustion; T cell reduction; T-Lymphocytes - immunology; COVID-19; T cell exhaustion; cytokine strom; T cell reduction; SARS- CoV-2
• ISSN: 1664-3224; 1664-3224
• DOI: 10.3389/fimmu.2020.00827

The outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has posed great threat to human health. T cells play a critical role in antiviral immunity but their numbers and functional state in COVID-19 patients remain largely unclear. We retrospectively reviewed the counts of T cells and serum cytokine concentration from data of 522 patients with laboratory-confirmed COVID-19 and 40 healthy controls. In addition, the expression of T cell exhaustion markers were measured in 14 COVID-19 cases. The number of total T cells, CD4 and CD8 T cells were dramatically reduced in COVID-19 patients, especially in patients requiring Intensive Care Unit (ICU) care. Counts of total T cells, CD8 T cells or CD4 T cells lower than 800, 300, or 400/μL, respectively, were negatively correlated with patient survival. T cell numbers were negatively correlated to serum IL-6, IL-10, and TNF-α concentration, with patients in the disease resolution period showing reduced IL-6, IL-10, and TNF-α concentrations and restored T cell counts. T cells from COVID-19 patients had significantly higher levels of the exhausted marker PD-1. Increasing PD-1 and Tim-3 expression on T cells was seen as patients progressed from prodromal to overtly symptomatic stages. T cell counts are reduced significantly in COVID-19 patients, and the surviving T cells appear functionally exhausted. Non-ICU patients with total T cells counts lower than 800/μL may still require urgent intervention, even in the immediate absence of more severe symptoms due to a high risk for further deterioration in condition.