IL-33 and basophils are augmented in inflamed mucosal tissues in IBD patients. (A) IL-33 release was measured in mucosal explants of patients with IBD or non-IBD. (B) Representative tissue basophil and MC dot plots of inflamed and noninflamed regions of 1 IBD patient (left panels), frequency of basophils (middle panel), and frequency of MCs (right panel) in CD45⁺ LPMCs isolated from inflamed and noninflamed sites in 17 IBD patients (11 CD and 6 UC patients). (C) Ratio of basophils/MCs in 10 IBD patients (5 CD and 5 UC patients). (D-E) T_EM stimulated with IL-2 (D) and T_CM stimulated with anti-CD3/28–coated beads (E) were cultured with or without basophils plus IL-33 in the absence or presence of antagonists to H₄R (10⁻⁵M) or H₂R (10⁻⁵M), respectively, or infliximab (10 μg/mL). IL-17 and IFN-γ expression was examined using intracytoplasmic staining after PMA ionomycin restimulation for 6 hours. Data represent means ± SEM for 5-8 donors. (F) Quantitative RT-PCR analysis of HRH2 and HRH4 in ex vivo isolated T_EM and T_CM. Data represent means ± SEM for 5 donors. *P < .05; **P < .01; ***P < .001 as determined by Mann-Whitney U test (A) and paired Student t test or Wilcoxon signed rank test (B-G).