Fig 2: IgE-producing PCs develop in the thymus.A Graph shows serum IgE levels in B6 and WT and Cd1d−/− BALB/c mice measured by ELISA at the indicated ages (N = 6–9). Dotted lines indicate the detection limit. B Graph shows serum IgE concentrations in sham-operated and thymectomized BALB/c mice (N = 13) measured by ELISA. C, D Total thymocytes of B6 and BALB/c mice were enriched for CD138+ cells by MACS and stained with indicated markers. Representative dot plots are shown after gating out TCRβ+ cells (C). Numbers indicate the total number of cells in adjacent gates (upper) or the frequency of cells in each quadrant (lower). Graph shows numbers of icIgE, icIgA and icIgG+ PCs and statistical analysis (N = 4–19) (D). Results are from more than three independent experiments. E Pie charts show mean frequencies of each isotype of PCs in the thymus, mLN, BM, and spleen (N = 3–4). Numbers indicate mean values of frequencies. F, G Indicated cells were purified by MACS enrichment followed by FACS sorting. CD3+CD4+CD11b+ cells were used as dump cells. Graph shows relative levels of mature Cε transcripts normalized to hprt by qPCR (N = 3) (F). Indicated cells were cultured for 5 days, and total IgE concentrations were measured in the supernatant (N = 3) (G). H Heat map shows MFIs of indicated markers in B220+CD19+ mature B and PCs in thymus and spleen measured by flow cytometry. Data were log2 transformed and visualized by relative expression per column. Data are presented as mean values ± SD (A, B, D, F, and G). Each dot represents an individual mouse. Unpaired two-tailed t-test (A, B, and G) and one-way ANOVA (D) were used for comparison. ***p < 0.001, **p < 0.01, *p < 0.05. Not significant (p > 0.05). Thx Thymectomy; U.D. Undetected; PC Plasma cell; Mat B Mature B cell.

Fig 3: Effect of PWRE on the production of IgE in the serum. The levels of (A) the total or (B) OVA-specific IgE in serum were evaluated by ELISA kits. The absorbance was measured at 450 nm with a microplate reader. #P<0.05 vs. NC group; *P<0.05 vs. OVA group. PWRE, P. weinmannifolia root extract; IgE, immunoglobulin E; OVA, ovalbumin; MON, montelukast; NC, negative control.

Fig 4: The level of homeostatic IgEs correlates with the severity of food anaphylaxis.A–D The figure shows experimental schematics for food anaphylaxis (FA) induction in Rag1−/− thymus-grafted and thymectomized BALB/ mice (A). Representative dot plots show IgE+ thymic PCs (left) and iNKT cells (right) in mice grafted with RAG1-deficient thymus (B). Numbers indicate frequencies of cells in adjacent gates. Graph shows body temperature changes in the indicated group (N = 3–4 for each group) (C). Graphs show serum concentrations of MCPT-1 measured by ELISA in indicated mice (D). E, F Twenty microliter of sera from NP-OVA immunized or unimmunized WT BALB/c mice were intradermally injected into ear pinnae of naïve WT and Cd1d−/− recipients. Recipient mice were intravenously injected with NP-OVA and Evans blue 24 h later. Pictures show ear pinnae from indicated mice (E), and graph shows concentrations of Evans blue dye in harvested ear pinnae (N = 4 for each group) (F). Data are presented as mean values ± SD (B, D, and F). Each dot represents an individual mouse. Unpaired two-tailed t-tests (B, D, and F) and two-way ANOVA (C) were used. ***p < 0.001, **p < 0.01, *p < 0.05. Not significant (p > 0.05). Thx Thymectomy; siLP Small intestinal lamina propria; MCPT-1 Mast cell protease-1.

Fig 5: PP downregulates the level of IgE in the serum of mice with OVA-induced airway inflammation. Serum levels of IgE were evaluated using ELISA kits. The absorbance was measured at 450 nm with a microplate reader. #P<0.05, vs. NC group; **P<0.01, vs. OVA group. PP, Physalis peruviana L.; IgE, immunoglobulin E; NC, normal control group; OVA, ovalbumin; DEX, dexamethasone + OVA; PP5, 5 mg/kg PP + OVA.