High CD26 and low CD94 expression identifies an IL-23 responsive V(delta)2+ T cell subset with a MAIT cell-like transcriptional profile

In this study, we find that CD26 and CD94 co-expression identifies transcriptionally distinct V(delta)2+ T cell subsets that vary in cytokine-responsiveness and cytotoxic potential, with a direct relationship between the loss of CD26 surface expression and upregulation of GzmB. These subsets differ in the expression of key transcriptional regulators including Tbet, Eomes and Hobit, and exist independently of classical memory markers. Analysis of cord blood samples confirms that CD26+ V(delta)2+ T cells predominate at birth, and we find evidence that IL-23 exposure and CD26 ligation may contribute to the generation of CD26- cytotoxic V(delta)2+ T cells in adults. Overall design: Samples 1-12: Freshly isolated PBMC from 3 healthy donors were stained for CD3, V(delta)2 TCR, CD26 and CD94. Cells were identified as Live/Dead negative, CD3+ V(delta)2+ cells. Four populations (CD26+CD94lo, CD26+CD94hi, CD26-CD94hi, CD26-CD94lo) were sorted from these PBMCs. Transcriptional profiling and differential gene expression was performed using RNA sequencing. Samples 13-28: For the V(delta)2 expansion RNA sequencing, individual CD26/CD94 V(delta)2 subsets were sorted from a single blood draw and expanded in parallel with (gamma-delta)-depleted PBMC, zoledronate, IL-2 and (if applicable) IL-23. At day 14 post-stimulation, cells were surface stained and live, CD3+ V(delta)2+ cells were sorted. Transcriptional profiling and differential gene expression was performed using RNA sequencing.