Figure 2.

CD4+ T cell responses to SARS-CoV-2 spike in mild, moderate, and severe COVID-19 donors. PBMCs from mild (n = 21, blue), moderate (n = 35, yellow), and severe (n = 33, red) acute COVID-19 donors were tested for CD4+ T cell responses to SARS-CoV-2 S by AIM + ICS assay. (A) AIM CD4+ T cell responses were measured by the co-expression of OX40 and CD69. The frequency of response is shown by pie charts. (B) The spike-specific cytokine+ CD4+ T cells were measured by the cells expressing CD40L in combination with production of IFNγ, granzyme B, TNFα, IL-2, IL-4, or IL-17. All T cell data shown are background subtracted and SI > 2. Horizontal lines represent the geometric mean and the dotted line represents the limit of sensitivity (LOS), while the y-axis starts at the limit of detection (LOD). p-values are calculated by Kruskal–Wallis One-way ANOVA and, when significant, further Mann–Whitney U tests are applied between disease severities. Chi-square test (χ²) p-values are indicated below the pie charts and are calculated from the frequency of response. * p < 0.05, ** p < 0.01.