Specificities of monoclonal antibodies to domain I of alpha-gliadins

Eight monoclonal antibodies were raised against a sequenced 54-amino-acid peptide of alpha-gliadin, which is thought to exacerbate coeliac disease. Five of the antibodies cross-reacted with coeliac non-toxic cereals. Two of eight of the antibodies bound specifically to coeliac toxic prolamins. These two antibodies cross-reacted with high molecular weight gliadins, which are closely related to alpha-gliadins and whose toxicity to patients with coeliac disease is unclear. The antibodies were screened by enzyme-linked immunosorbent assay against three amino-acid-sequenced peptides of alpha-gliadin with single amino-acid differences. Differential binding of antibody WC2 suggested that this antibody binds in the region of amino-acid residue 36, a proline residue, where there may be an antigenic beta-reverse turn. This proline residue forms part of a tetrapeptide motif, QQQP, which is thought to be present in all coeliac-active peptides.