TBX21 and inflammatory bowel disease: Clusters with increased frequencies in active IBD (p.adj < 0.05) included IL-17-producing T cells (cl11.1 and 11.2), proliferating T cells (cl17), regulatory T cells (Tregs; cl7), and CD8+TBX21+ cytotoxic T cells (cl18) (Figures 2F and 2G).