Fig 2: Correlation of tumor infiltration with eosinophils and CD8+ T cells. Consecutive paraffin sections of primary tumors (n = 10) as well as metastases pre- (n = 18) and post-treatment (n = 5) were stained with hematoxylin/eosin (HE), anti-human MBP and CD8 antibodies. (a) Representative images of eosinophils stained with an anti-MBP antibodies. (b) The percentage of eosinophils within granulocytes in the peripheral blood determined by flow cytometry was plotted against eosinophil numbers in primary tumors assessed by immunohistochemistry. (c) Activated eosinophils in the intratumoral region of section from primary tumors as well as metastases pre- and post-treatment were determined by degranulation of MBP-positive vesicles. The results are presented as the percentage of activated among total tumor-infiltrating eosinophils (d) Representative images of consecutive paraffin sections of primary tumors, metastases pre- and post-treatment stained with HE, anti-MBP and anti-CD8 antibodies. (e) The numbers of eosinophils in the intratumoral region of primary tumors, metastases pre- and post-treatment in responders and non-responders was plotted against CD8+ T cell numbers in consecutive sections of these regions. (f) The numbers of eosinophils in the peri- and intratumoral region of metastases pre- and post-treatment was plotted against CD8+ T cell numbers in consecutive sections of these lesions. Responders were characterized by CR, PR, and SD. *P < .05.

Fig 3: Yokukansan (YKS) decreased the infiltration of eosinophils into the gastroduodenal tract of maternal stress (MS) rats. (A) Low-magnification pictures show that the major basic protein (MBP)–immunoreactive (ir) cells are mainly located in the mucosa (Mu) of the stomach and duodenum, and there are very few cells in the submucosa (SM) and muscle (Ms) layer. High-magnification pictures show the MBP-ir cells in the stomach of vehicle- and YKS-treated rats in each group. (B) The bar graph shows the statistics of MBP–ir cells in the stomachs of each group. (C) The bar graph shows the statistics of MBP–ir cells in the duodenums of each group (n = 3 in each group, data analyzed by unpaired t test. *P < 0.05, **P < 0.01, ***P < 0.001. Data are presented as the mean ± SEM; scale bar: 50 µm).

Fig 4: The number of MRGPRX2+, CST+, and MBP+ cells is increased in the lesions of patients with indolent systemic mastocytosis. Immunohistochemical staining of (A) MRGPRX2, (C) CST, and (E) MBP in the lesional and non-lesional skin of patients with ISM #6, #10, and #13, respectively. ×200 magnification of upper picture; ×400 magnification of all other pictures (expressing cells are shown by arrows). Bar = 50 µm. Number of (B) MRGPRX2+ cells, (D) CST+ cells, and (F) MBP+ cells in lesional and non-lesional skin of patients with ISM and skin of healthy controls. p < 0.05 was considered significant. The number of patients and controls as well as means/medians are summarized in the Table 2 . CST, cortistatin; ISM, indolent systemic mastocytosis; MBP, major basic protein; NS, non-significant.

Fig 5: PD-L1+CD80+ A-Eos are specific to the mouse GI and enriched in human IBD.a, Representative FACS plots of PD-L1+CD80+ and PD-L1- CD80- eosinophils (n = 3, B6J). Numbers indicate % of eosinophils. b,c, UMAP of eosinophil transcriptomes (shown in Fig. 1a) including those isolated from uterus, lung and adipose tissue (n = 4, Il5-tg). Cells coloured by organ (b) and by cluster (c). d, Subset distribution across organs (% of eosinophils). e, List of shared or unique markers (logFC > 0.5, P adjusted < 0.05) between A-Eos and tissue eosinophils. Non-parametric Wilcoxon rank sum test (FindMarkers function in Seurat). f, Representative FACS plots of PD-L1+CD80+and PD-L1-CD80- eosinophils in HDM- or PBS-treated mice (n = 2, B6J). Numbers indicate % of eosinophils. g, Left: Gating strategy used to identify resident (rEos) and inflammatory (iEos) eosinophils as described by17. Right: quantification of PD-L1+CD80+ and PD-L1-CD80- eosinophils in rEos and iEos. Medians are shown. h, MBP and PD-L1 immunofluorescence staining of human tissue microarrays. Representative cores from a healthy individual and a patient with Crohn’s disease are shown (n = 5). Scale bars, 500 µm (core overview) and 10 µm (high magnification insets).