A monoclonal antibody that recognizes a potential coeliac-toxic repetitive pentapeptide epitope in gliadins

Abstract

Antibodies that detect coeliac-toxic prolamins from wheat, barley and rye are important tools for controlling the diet of coeliac disease patients. Recently, a monoclonal antibody R5 that recognizes wheat gliadin, barley hordein and rye secalin equally was described. In this study, the epitope recognized by R5 was investigated. Both a phage-displayed heptapeptide library and overlapping peptides spanning the sequence of alpha- and gamma-type gliadins (pepscan) were screened for binding of R5. Both techniques yielded comparable pentapeptide consensus sequences (phage display QXPW/FP; pepscan QQPFP). According to recent observations, this peptide stretch may be of key importance in the pathogenicity of coeliac disease. This sequence occurs repetitively in prolamins (in gamma- and omega-type prolamins more frequently than in alpha-type prolamins) together with several homologous peptide stretches, which are recognized less strongly. R5 seems to be a good candidate for the specific detection of putative coeliac disease-active sequences in prolamins and thus represents a valuable tool for the quality control of gluten-free food.