Background: The mechanisms of gastrointestinal (GI) food allergy (FA) are poorly understood. Immunoglobulin E (IgE) is increased in stools from patients with FA, as well as the number of cells carrying IgE in intestinal mucosa, but the origin of IgE production remains unknown. To investigate a local production of IgE in intestine, we analysed the levels of transcripts for epsilon germ-line (epsilonGT), and potential regulators of IgE production, IL-4, IL-13, IFN-gamma, IL-4Ralpha, STAT6 and FcepsilonRIalpha in intestinal mucosa of adult patients with FA.
Methods: Endoscopic biopsies were obtained from the caecum of 25 patients with FA and 14 control patients. The levels of epsilonGT, IL-4, IL-13, IFN-gamma, IL-4Ralpha, STAT6 and FcepsilonRIalpha mRNA were analysed by real-time RT-PCR and compared with unpaired nonparametric Mann-Whitney test.
Results: The mean epsilonGT transcript level in caecum was increased in FA patients compared with control patients (P < 0.05). IL-4 mRNA expression was also increased in FA patients (P < 0.05), whereas mRNA expression for IL-13, IFN-gamma, IL-4Ralpha, STAT6 and FcepsilonRIalpha mRNA expression was not altered. However, the ratio of IL-4 mRNA/IFN-gamma mRNA was significantly increased in FA patients (P < 0.05). No correlation was observed between epsilonGT transcripts expression in intestinal mucosa and total IgE levels in serum.
Conclusions: This study shows that (i) epsilonGT transcripts are expressed in human intestinal mucosa; (ii) epsilonGT and IL-4 transcripts are increased in caecal mucosa from patients with FA. These results suggest local production of IgE in intestine that might be of importance for inflammatory reactions in the GI tract.