Figure 2.

Ex vivo T cell-mediated cellular response Spike-specific of SARS-CoV-2 following prime boost vaccination in naïve and individuals recovered from COVID-19. (A) Experimental design of the ex vivo T cell-mediated cellular responses in PBMCs, to address early and late responses to the second and third (boost) vaccination, after stimulation with the SARS-CoV-2 wild-type (WT) Spike peptide pool. (B) TNFα, IL-6, IL-2, IFNγ, CXCL10, IL-1β, IL-17A, and IL-10 production in naïve participants and recovered from COVID-19 at the indicated sample numbers. (C) Increment of proliferation (CFSE^dim) comparing SARS-CoV-2 Spike peptide pool-stimulated and non-stimulated CD4⁺ (left panel) and CD8⁺ (right panel) T cells in naïve participants and those recovered from COVID-19 at the indicated sample numbers. Data in (B, C) are shown as mean ± min to max. Each dot represents a single participant. Unpaired Student’s t-test or Mann–Whitney test according to normality, comparing naïve and subjects recovered from COVID-19 at each sample (#p < 0.05). Paired Student’s t-test or Wilcoxon test according to normality, comparing samples along the time in naïve subjects and those recovered from COVID-19 (*p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001). In every plot, all the possible experimental conditions were compared; statistically significant differences are indicated, and the lack of statistical indication means the absence of a significant difference.