Background: It is well established that the wheat protein gliadin triggers inflammation in coeliac patients. However, the potential toxicity of avenin, the equivalent protein in oats, is debated. Aim: To investigate the immunogenicity of avenin using the cytokines interferon γ (IFN-γ) and interleukin (IL)-2 as markers of immunological activity. Methods: Duodenal biopsies from coeliac patients were cultured with 5 mg/ml of peptic tryptic (PT) gliadin (n=9) or 5 mg/ml of PT avenin (n=8) for four hours. Biopsies cultured with RPMI 1640 alone served as controls. Non-coeliac biopsies were also cultured with PT gliadin (n=8) and PT avenin (n=8). Total RNA was extracted from the tissue after culture. Cytokine mRNA was quantified by TaqMan polymerase chain reaction. Secreted cytokine protein was measured in the culture supernatant by enzyme linked immunosorbent assay. Results: After culture with PT gliadin, an increase in IFN-γ mRNA was observed in all nine patients with coeliac disease. Increased IFN-γ protein was also found in four of these patients. Smaller increases in IL-2 mRNA were detected in six subjects with increased IL-2 protein found in two patients. In contrast with PT gliadin, there was no significant IFN-γ or IL-2 response when coeliac biopsies were cultured with PT avenin. Similarly, biopsies from normal controls did not respond to PT gliadin or PT avenin stimulation. Conclusions: The findings of this study suggest that the immunogenic sequences in gliadin are not present in avenin. Moreover, they are in keeping with in vivo studies which report that oats are safe for consumption by coeliac patients.
Celiac disease is caused by sensitivity to wheat gluten in genetically susceptible individuals. The etiological role of the other wheat-related cereals, barley, rye, and oats, is still debated. In order to investigate this issue further, in this study we examined the immune response of celiac mucosal T cell lines to fractions from all four cereals. Cell stimulation was assessed by measuring proliferation (employing (3)H-thymidine incorporation) or cytokine (IL-2, IFN-gamma) production. All five T cell lines demonstrated immunoreactivity to protein fractions from the four related cereals. In some cell lines, reactivity to wheat, barley, and rye was only evident when these cereal fractions had been pretreated with tissue transglutaminase. This study confirms the similar T cell antigenic reactivity of these four related cereals and has implications for their exclusion in the gluten-free diet. However, despite oats stimulation of T cell lines, this cereal does not activate a mucosal lesion in most celiac patients.
SUMMARY
BackgroundIn coeliac disease, wheat, barley and rye are traditionally excluded in the gluten-free diet. However, few studies have examined the small intestinal immune response to barley and rye.
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