They also reported that (3) IL-33 maturates active eosinophils in vitro and in vivo, (4) IL-33 promotes active eosinophil accumulation in a mouse colitis model and IFN-γ enhances the effect of IL-33, and finally (5) active eosinophils colocalize with CD4+ T cells based on in situ RNA imaging in colon sections from patients with ulcerative colitis (N = 3), suggesting the heterogeneity of eosinophils in the intestine and the key roles of active eosinophils in colitis [111]. The gene discussed is IL33; the disease is ulcerative colitis.