PDCD1 and inflammatory bowel disease: Patients in the IBD group had higher levels of PD-1 + cells than the OID group (median 243 cells/mm2 vs. 94 cells/mm2, p = 0.028), as well as higher PD-1 + Th (96 cells/mm2 vs. 19 cells/mm2, p = 0.008) and PD-1 + Treg levels (11 cells/mm2 vs. 4 cells/mm2, p = 0.024) (Fig. 1, Supplementary Table S1).