Variation of serum and intestinal gluten antibody specificities in coeliac disease

Protein blotting techniques were used to investigate the gluten specificity of IgA and IgG antibodies in sera and intestinal aspirates from patients with coeliac disease and normal controls. Initially, discontinuous SDS polyacrylamide gel electrophoresis was used to separate the flour proteins. All normal and coeliac sera contained antibodies which bound to various of the gliadin proteins. In only a few sera was binding found to the high molecular weight glutenin subunits, while none was detected to the salt-soluble wheat proteins. Polyacrylamide gradient gel electrophoresis was then used to further separate the gliadin proteins. Almost all normal sera examined showed similar gliadin specificity, binding uniformly to all gliadin groups. While approximately a quarter of the coeliac sera showed even binding to all of the gliadin proteins, the majority showed antibody binding intensely to discrete groups of gliadin bands. We were unable to identify any gliadin band(s) which only bound antibodies from coeliac patients in comparison with normal subjects. The specificities of IgG and IgA serum antibodies were identical for each patient examined, but some differences between serum and intestinal IgA specificities were found for certain patients.