Polyfunctional and cytotoxic specific T-cell responses of convalescent COVID-19 patients after in-vitro stimulation with the CD40.CoV2 vaccine. (a) Representative dot plots of SARS-CoV-2-specific CD4+ and CD8+ T-cell responses after in vitro stimulation of patient PBMCs with the CD40.CoV2 vaccine (1 nM) on D0 and re-stimulation with various vOLPs (vRBD, vS1, vS2 or vN2) (1 µg/ml) on D8. (b) Functional composition of SARS-CoV-2-specific CD4+ and CD8+ T-cell responses induced by the CD40.CoV2 vaccine and various vOLPs (vRBD, vS1, vS2 or vN2) (1 µg/ml). Responses are color coded according to the combination of cytokines produced. The arcs identify cytokine-producing subsets (IFN-γ, IL-2, and TNF) within the CD4+ or CD8+ T cell populations. (c) Frequency and radar charts of the merged median of IFN-γ+ SARS-CoV-2-specific CD4+ (blue) or CD8+ (green) T cells from convalescent COVID-19 patients (n = 14) stimulated or not with the CD40.CoV2 vaccine (1 nM) on D0 and re-stimulated with various vOLPs (vRBD, vS1, vS2 or vN2), cont.OLP (SARS-CoV-2 N1-N2, or Ebola Gpz) (grey) on D8 (1 µg/mL). Median values ± IQRs are shown. [Friedman and Dunn's multiple comparison tests] were used for statistical analysis (*P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, ns: not significant). (d) Specific lysis of CD8+ T cells stimulated with the CD40.CoV2 vaccine (1 nM) against autologous PHA-blasted PBMCs from five different convalescent COVID-19 patients, pulsed with either vRBD (light green), vN2 (dark green), or cont.OLP (SARS-CoV-2 N1-N2 or M) (grey). The means of triplicate values ± the standard deviation (SD) are shown. Each symbol represents a different patient.