FIGURE 1.

Il33 is mainly expressed by intestinal stromal cells. (A) Flow cytometric plot of intestinal stromal cells from IL-33-eGFP reporter mice. (B) Flow cytometric histograms of IL-33 expression in intestinal stromal cells, intestinal epithelial cells (IEC), dendritic cells (DC), macrophages (Mph) and eosinophils (Eos) from IL-33-eGFP reporter mice. (C) Percentage of IL-33 expression from (B), with addition of neutrophils and NK cells. (D), Expression of Il33 gene in sort-purified intestinal epithelial cells (EpCAM⁺), intestinal IL-33-eGFP^- stromal cells and IL-33-eGFP⁺ stromal cells (PDGFR- $\alpha$ ⁺, Sca-1⁺) from IL-33-eGFP reporter mice. (E) Immunofluorescence of sort-purified IL-33-eGFP⁺ cultured stromal cells. IL-33 expression is represented by eGFP reporter expression in green. (F) Flow cytometric plots of small intestine ILC2s from WT mice after co-culture with IL-7, IL-7 and stromal cells, or IL-7 and IL-33. ILC2s were gated on live CD45⁺ Lin⁻ (CD3, CD5, CD19, Ly6g, and Fcer1), CD127⁺ and KLRG1⁺. (G) Evaluation of ILC2 activation from F after 3 days in culture with cytokines IL-7 or IL-7 and stromal cells or IL-7, IL-33. (H) Flow cytometric plots and evaluation of CD81 expression of small intestine stromal cells from IL-33-eGFP mice. Stromal cells were gated on LD, CD45⁻, PDGFR-α⁺ and IL-33⁺ or IL-33⁻. (C, D, G, H): Each symbol represents data from 1 mouse, data are representative of two experiments with three to four mice per group. Mean±SD, Student’s t-test or one-way ANOVA. ns not significant, **p < 0.01, ***p < 0.001, ****p < 0.0001.