Anti-alpha-gliadin antibodies (AGA) in the serum of coeliac children and controls recognize an identical collection of linear epitopes of alpha-gliadin.

Anti-gliadin antibodies can be found in the serum of patients with overt and subclinical coeliac disease, but also in that of some controls. The aim of the present study was to identify the linear epitopes of the alpha-gliadin molecule to which the humoral response is directed. Therefore, the IgG and IgA antibody reactivity against an overlapping set of synthetic peptides covering the entire sequence of alpha-gliadin was measured in the sera from patients with coeliac disease, from controls with elevated titres of anti-gliadin antibodies and from healthy children using an ELISA technique. The antibodies mainly recognize peptides derived from the N-terminal region of alpha-gliadin, containing the motif QPFXXQXPY. Reactivity was also detected against two other synthetic peptides, which do not contain this motif and represent a sequence encoded further to the C-terminal region of alpha-gliadin. Anti-gliadin antibodies in sera from patients with coeliac disease and from controls recognize the same linear epitopes. Thus, serological investigation of the specificity of these antibodies using a peptide ELISA does not allow discrimination between patients and controls.