Fig. 5: Polyfunctionality and proliferation capacity of SARS-CoV-2-specific T cells.

PBMC samples (n = 90) from individuals with SARS-CoV-2 infection (n = 39) were stimulated with OLPs of S, M, or N (1 μg/mL) for 6 h. Intracellular cytokine staining was performed to examine the frequency of polyfunctional cells exhibiting positivity for ≥2 effector functions among SARS-CoV-2-specific CD4⁺ and CD8⁺ T cells. a Representative flow cytometry plots showing the frequency of polyfunctional cells among CD4⁺ (left) and CD8⁺ (right) T cells. b Scatter plots showing the relationship between DPSO and the frequency of polyfunctional cells among SARS-CoV-2-specific CD4⁺ (upper) or CD8⁺ (lower) T cells. The black line is a LOESS smooth nonparametric function, and the gray shading represents the 95% confidence interval. c The fraction of polyfunctional cells among SARS-CoV-2-specific CD4⁺ (left) or CD8⁺ (right) T cells was compared between T1 (n = 17, 31–99 DPSO), T2 (n = 39, 100–199 DPSO), and T3 (n = 25, ≥200 DPSO). Data are presented as median and IQR. d Pie charts showing the fraction of cells positive for a given number of functions among SARS-CoV-2-specific CD4⁺ (left) or CD8⁺ (right) T cells. Each arc in the pie chart represents the indicated function. e CTV-labeled PBMCs (n = 18) obtained after 200 DPSO were stimulated with S OLP pool (1 μg/mL) for 120 h and the frequency of CTV^low and Ki-67⁺ cells among CD4⁺ and CD8⁺ T cells was analyzed. Representative plots (upper) and summary data (lower) are presented. Statistical analysis was performed using the two-sided Kruskal–Wallis test with Dunns’ multiple comparisons test (c) or the two-sided Wilcoxon signed-rank test (e). n.s, not significant.