Robust T Cell Response Toward Spike, Membrane, and Nucleocapsid SARS-CoV-2 Proteins Is Not Associated with Recovery in Critical COVID-19 Patients

T cell immunity toward SARS-CoV-2 spike (S-), membrane (M-), and nucleocapsid (N-) proteins may define COVID-19 severity. Therefore, we compare the SARS-CoV-2-reactive T cell responses in moderate, severe, and critical COVID-19 patients and unexposed donors. Overlapping peptide pools of all three proteins induce SARS-CoV-2-reactive T cell response with dominance of CD4+ over CD8+ T cells and demonstrate interindividual immunity against the three proteins. M-protein induces the highest frequencies of CD4+ T cells, suggesting its relevance for diagnosis and vaccination. The T cell response of critical COVID-19 patients is robust and comparable or even superior to non-critical patients. Virus clearance and COVID-19 survival are not associated with either SARS-CoV-2 T cell kinetics or magnitude of T cell responses, respectively. Thus, our data do not support the hypothesis of insufficient SARS-CoV-2-reactive immunity in critical COVID-19. Conversely, it indicates that activation of differentiated memory effector T cells could cause hyperreactivity and immunopathogenesis in critical patients.
Graphical Abstract
Highlights M-, N-, and S-proteins induce T cell reactivity with differing immune dominance M-protein triggers a strong CD4+ T cell response ICU and non-ICU COVID-19 patients have comparable SARS-CoV-2 T cell responses Viral clearance and COVID-19 survival are not associated with SARS-CoV-2 immunity
Thieme et al. demonstrate the T cell response against M-, N-, and S-proteins of SARS-CoV-2, with M-protein triggering a stronger CD4+ T cell response. ICU COVID-19 patients are capable of generating functional SARS-CoV-2 immunity non-inferior to non-ICU COVID-19 patients. SARS-CoV-2 clearance and COVID-19 survival are not associated with the magnitude of T cell response.