IgA anti-gliadin antibody immunoreactivity to food proteins

We developed a competitive enzyme-linked immunosorbent assay (cELISA) based on bread wheat flour gliadin as coated antigen and human serum IgA as primary antibody in order to quantify the immunoreactivity of untreated celiac patient IgA antigliadin antibodies (AGAs) to different food proteins. No significant AGA immunoreactivity to bovine serum albumin or zeins was detected, but there was considerable immunoreactivity to caseins: 39% to bovine caseins and 65% to goat caseins (base gliadin reactivity: 100%). We also investigated AGA immunoreactivity to the same proteins after peptic-pancreatic digestion. Taken together, the results suggest that AGA immunoreactivity to gliadins and caseins could be due to the β-turn content in these proteins and that a minor portion of serum AGAs from untreated celiac patients is represented by antibodies recognizing linear epitopes.