Background: Marked progress is achieved in understanding the physiopathology of COVID-19 that caused global pandemics. However, CD4+ T cell population that is critical for antibody response in COVID-19 is poorly understood. Methods: In this study, we provided a comprehensive analysis of peripheral CD4+ T cells of 13 COVID-19 convalescent patients, as defined as confirmed free of SARS-CoV-2 for 2-4 weeks, using flow cytometry, magnetic chemiluminescence enzyme antibody immunoassay and correlated the data with clinical characteristics. Results: We observed that relative to healthy individuals, convalescent patients displayed an altered peripheral CD4+ T cell spectrum. Specifically, consistent with other viral infections, cTFH1 cell associated with SARS-CoV-2 targeting antibodies, which was found to skew with disease severity as more severe individuals showed higher frequency of TEM and TFH-EM cells but a lower frequency of TCM, TFH-CM and TNaive cells, relative to mild and moderate patients. Interestingly, higher frequency of cTFH-EM cells correlated with lower number of recorded admission blood oxygen level in convalescent patients. These observations might constitute residual effects by which COVID-19 can impact the homeostasis of CD4+ T cells in the long-term and explain the highest ratio of class-switched virus-specific antibody producing individuals found in our severe COVID-19 cohort. Conclusion: Together, our study demonstrated close connection between CD4+ T cells and antibody production in COVID-19 convalescents.Funding: This study was supported by Six Talent Peaks Project in Jiangsu Province and the National Natural Science Foundation of China (NSFC) grants 81970759.
Fang Gong, Yaping Dai, Ting Zheng, Liang Cheng, Dan Zhao, Hao Wang, Min Liu, Hao Pei, Tengchuan Jin, Di Yu, Pengcheng Zhou