Background: Patients infected with SARS-CoV-2 differ in the severity of disease. We hypothesized that characteristics of SARS-CoV-2 specific immunity correlate with disease severity. Methods: In this study, SARS-CoV-2 specific T-cells and antibodies were characterized in uninfected controls and patients with different COVID-19 related disease severity. SARS-CoV-2 specific T-cells were flow-cytometrically quantified after stimulation with SARS-CoV-2 peptide pools and analyzed for expression of cytokines (IFNγ, IL-2 and TNFα) and markers for activation, proliferation and functional anergy. SARS-CoV-2 specific IgG and IgA antibodies were quantified using ELISA. Moreover, global characteristics of lymphocyte subpopulations were compared between patient groups and uninfected controls Results: Despite severe lymphopenia affecting all major lymphocyte subpopulations, patients with severe disease mounted significantly higher levels of SARS-CoV-2 specific T-cells as compared to convalescent individuals. SARS-CoV-2 specific CD4 T-cells dominated over CD8 T-cells and closely correlated with the number of plasmablasts and SARS-CoV-2 specific IgA- and IgG-levels. Unlike in convalescents, SARS-CoV-2 specific T-cells in patients with severe disease showed marked alterations in phenotypical and functional properties, which also extended to CD4 and CD8 T-cells in general. Conclusion: Given the strong induction of specific immunity to control viral replication in patients with severe disease, the functionally altered characteristics may result from the need for contraction of specific and general immunity to counteract excessive immunopathology in the lung. Trial registration: n.a. Funding: The study was supported by institutional funds by M.S., and in part by grants of Saarland University (to M.S. and. R.B), the State of Saarland, and the Dr. Rolf M. Schwiete Stiftung to R.B.
David Schub, Verena Klemis, Sophie Schneitler, Janine Mihm, Philipp M. Lepper, Heinrike Wilkens, Robert Bals, Hermann Eichler, Barbara C. Gärtner, Sören L. Becker, Urban Sester, Martina Sester, Tina Schmidt