Fig. 1: Functional characteristics of acute SARS-CoV-2-specific T cells.

a Comparison of the net frequency (background subtracted) of interferon (IFN)γ, CD107a, interleukin (IL)-4, and IL-10 expression in SARS-CoV-2-specific CD4⁺ and CD8⁺T cells in response to viral proteins (membrane (M), nucleocapsid (N), and spike (S)) between study groups (nonhospitalized n = 14 in orange; mild n = 20 in blue and severe n = 12 in pink). Statistical comparisons were performed using Kruskal–Wallis rank-sum test with Dunn’s multiple comparison test (two-sided): CD4⁺ IFNγ (M, p = 0.020 and p = 0.004; N, p = 0.011 and S, p = 0.020 and p = 0.007) and IL-10 (M, p = 0.035); CD8⁺ CD107a (M, p = 0.037), IL-4 (S, p = 0.004 and p = 0.003). b Donut charts summarizing the contribution of each function to the overall CD4⁺- and CD8⁺-specific T cell response by targeted viral protein and individual group of patients. Data represent the mean value of the net frequency of each function indicated by color code considering all patients, responders and nonresponders. Total response value (%) is shown under each pie chart and represents the cohort average of the overall net frequency considering all individuals and adding up all functions (nonhospitalized n = 14; mild n = 20 and severe n = 12). Statistical comparisons as performed in a are indicated with * and ** symbols. c Donut charts summarizing the distribution of individual functions among specific CD4⁺ and CD8⁺T cells to either the M, N, or S protein from the only fatal case within the severe COVID-19 group.