Fig. 4.

CD26^high T cells are multi-functional and enzymatically active. CD4⁺ T cells from healthy individuals were isolated and sorted by CD26 expression (Fig. 2a). a, b Sorted T cells were activated with PMA/Ionomycin and Monensin for 4 h prior to intracellular staining (N = 26). In b, three independent donors were analyzed by FlowJo software and graphed to display the percentage of cells simultaneously secreting 1–5 cytokines (IL-2, IFNγ, TNFα, IL-17A, IL-22). c Supernatant was collected from cells at pre-activation (0) and 1, 6, and 12 days post-activation time points for ELISA (N = 2; data shown is representative of two individual experiments). d T cells activated in vitro were subjected to intracellular staining (N = 5–11). e 1e⁵ sorted cells per group from pre-activation (0) and 10 days post-activation were cultured with the CD26 ligand gly-pro-P-nitroanalide for 2 h at 37 °C and analyzed for colorimetric changes to determine enzymatic activity (N = 5). P values in a and e were calculated by One-way ANOVA with a Kruskal-Wallis comparison. Error bars represent mean ± SEM. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001