Fig. 3.

CD26 defines CD4⁺ T cells with naive, helper, or regulatory properties. CD4⁺ T cells were isolated from healthy donors and sorted by CD26 expression (Fig. 2a). Representative FACS plots (a) and phenotype data (b N = 26) from multiple healthy individuals. c Heat map of (+/−) log2-fold change in expression of CD4⁺ subset-associated genes (N = 3–5) prior to bead stimulation. d, e Human CD4⁺ T cells were sorted into bulk CD4⁺, CD26^neg, CD26^int, CD26^high, Th1 (CXCR3⁺CCR6⁻), Th2 (CCR4⁺CCR6⁻), Th17 (CCR6⁺CCR4⁺), and Th1/Th17 (CXCR3⁺CCR6⁺). DNA was isolated from sorted T cells prior to expansion of TCRβ sequences using an immunoSEQ kit and subsequent analysis. Data shown is the percent TCRβ overlap between groups (d) and a Venn diagram (e) displaying the overlap frequencies of identical TCRβ sequences between CD26^neg, CD26^int, CD26^high, and Th1/Th17 subsets (N = 4). P values for b and d were calculated using one-way ANOVA with a Kruskal-Wallis comparison. Error bars represent mean ± SEM. *P < 0.05; **P < 0.01; ****P < 0.0001