ABSTRACT
Background: The coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has gradually become a global public health crisis. Some patients who have recovered from COVID-19 subsequently tested positive again for SARS-CoV-2 after discharge (retesting-positive, RTP). However, the underlying mechanism is unknown.Methods: Here, 30 RTP patients, 20 convalescent patients, and 20 healthy controls were enrolled for analysis of the immunological characteristics of their peripheral blood mononuclear cells (PBMCs). Furthermore, we sought to comprehensively characterize the transcriptional changes in the three groups by transcriptome sequencing.Findings: It was found that the absolute numbers of CD4+ T cells, CD8+ T cells, and NK cells were not decreased remarkably, while the expression of activation markers on these cells was significantly decreased in RTP patients. Furthermore, the percentage of granzyme B-producing T cells was also decreased in RTP patients compared with that in convalescent patients. Moreover, the high expression of inhibitor of differentiation-1 (ID1) and the low expression of IFITM10 may be associated with the insufficient activation of immune cells and RTP occurrence.Interpretation: Our findings provide insights into the impaired immune function and pathogenesis of RTP occurrence in COVID-19, which may contribute to the development of immunotherapy for RTP patients.Funding Statement: This work was supported by China National Center for Biotechnology Development (2020YFC0843800 and 2020YFC0846800), Ministry of Science and Technology of China (2020TFC0844100), and China Postdoctoral Science Foundation (2020T130112ZX).Declaration of Interests: The authors declare no potential conflict of interest.Ethics Approval Statement: The studies were approved by the Ethics Committee of the First Affiliated Hospital of the University of Science & Technology of China (2020-XG(H)-005) and Peking University First Hospital (2020-Research-112) for Emerging Infectious Diseases. Experiments were conducted in accordance with the ethical guidelines of the 1975 Declaration of Helsinki, the Principles of Good Clinical Practice, and the guidelines of China’s regulatory requirements.