Peripheral blood dendritic cells, monocytes, basophils, and neutrophils express FcεRI, CD23 and receptor-bound IgE at the cell surface.

<p>Number of positive cells, median and range of % positive cells among the respective population is shown. If n = 1, the % positive cells in this patient is displayed.</p

Peripheral blood cells carry IgE, even in the absence of elevated serum IgE.

<p>The percentages of IgE-loaded FcεRI+ peripheral blood cells did not significantly differ between patients with elevated versus normal serum IgE (Mann-Whitney-U-test). However, some patients with normal serum IgE showed high levels of cell-bound IgE.</p

Serum IgE enhances FcεRI on dendritic cells and monocytes from patients with elevated IgE.

<p><b>A</b>. Cell surface levels of FcεRI on dendritic cells and monocytes correlate with serum IgE in children with elevated IgE. <b>B</b>. No correlation was found in patients with normal serum IgE. Data points represent percent (%) positive cells among cell type after subtraction of isotype control background in individual patients.</p

Cell surface-bound IgE correlates with serum IgE and IgE-receptor expression.

<p><b>A</b>. Surface-bound IgE in FcεRI+ DC, monocytes, and neutrophils correlates with serum IgE. <b>B</b>. FcεRI-expression correlates with surface-bound IgE in FcεR+ DC, monocytes, and basophils, CD23-expression correlates with surface-bound IgE in CD23+ DC and monocytes (Spearman rank correlation, respectively).</p><p>*p<0.05.</p

FcεRI expression increases with age in dendritic cells and monocytes.

<p>Data points represent percent (%) positive cells among cell type after subtraction of isotype control background in individual children.</p

FcεRI mRNA expression levels in the upper gastrointestinal tract under inflammatory conditions.

<p>(A) FcεRIα-, (B) FcεRIβ-, and (C) FcεRIγ-mRNA expression levels in specimens from children with gastritis/esophagitis (open squares), celiac disease (open triangles), inflammatory bowel disease (IBD) (open diamonds), and normal mucosa (open circles). * p<0.05, Kruskal-Wallis test.</p

Immunohistochemistry with FcεRIα specific antibody (mAb 15-1) on snap-frozen intestinal specimens from (A) the esophagus, (B) the stomach, (C) the duodenum, and (D) the colon.

<p>FcεRIα-positive cells (red) are frequently found in the esophagus, the stomach, and the duodenum (black arrows). (E) shows isotype control with mouse IgG1. Goblet cells in the duodenum and the colon revealed non-specific binding of antibodies. Original magnification x20. Bottom row (F-J) shows details from A-E. Representative specimens from n = 10.</p

Patients’ characteristics.

<p>IBD: inflammatory bowel disease.</p

c-kit positive mast cells in the esophagus epithelium express FcεRIα.

<p>(A) FcεRIα is visualized with mAb Cra1 (green, first panel). Mast cells are shown with c-kit as a marker (red, second panel). Cell nuclei are visualized with DAPI staining (blue). (B) shows higher magnifications from (A). FcεRIα is expressed on esophageal mast cells (B, white arrows). Representative specimens from n = 3.</p

Quantitative RT-PCR for the three subunits of the high affinity IgE-receptor was performed on intestinal biopsies from pediatric patients.

<p>(A) FcεRIα mRNA transcripts were found in all esophageal biopsies and with varying frequency in more distal biopsies (left panel). Similarly, the highest frequency of FcεRIβ mRNA-positive specimens was found in the esophagus (middle panel). The common Fc-γ chain was detected in the majority of specimens from the entire GI tract (right panel). Black stacked-bars represent target-positive specimens, and white stacked-bars represent target-negative specimens. (B) The highest levels of FcεRIα mRNA transcripts were found in the esophageal mucosa (left panel), while FcεRIβ mRNA expression peaked in the gastric mucosa (middle panel). Esophageal specimens revealed the lowest FcεRIγ mRNA expression compared to the stomach, terminal ileum, colon, and rectum (right panel). * p<0.05, Mann-Whitney-U test.</p