Identification of reactive synthetic gliadin peptides specific for coeliac disease

Gluten intolerance (coeliac disease) is characterised by the development of a small intestinal lesion following exposure to the gliadin fraction after consumption of wheat and related cereals. Cellular immune mechanisms are thought to be responsible for gliadin toxicity, but the toxic sequence/s within gliadin have not been clearly established. A panel of synthetic gliadin peptides was tested using peripheral blood mononuclear cells from coeliac patients and two assays for cell-mediated immunity. Using the indirect leucocyte migration inhibition factor and the macrophage procoagulant activity assays, gliadin peptides which were located in the aminoterminal or the proline-rich domain of the alpha/beta gliadin molecule were coeliac-active. Peptides predicted by T cell algorithms or on the basis of homology to adenovirus Ad12 Elb protein and which were located in the proline-poor gliadin domains were inactive. Protein sequence studies which indicate significant homology in the proline-poor gliadin domains with a number of non-coeliac-toxic seed proteins also supported the hypothesis that the proline-rich domains may be more important in the pathogenesis of coeliac disease.