IgA but not IgG serum antibodies to maize prolamins in Mexican patients with celiac disease (CD) and irritable bowel syndrome (IBS) (BA15P.226)

High prevalence of CD has been found in IBS patients. CD is a chronic immune-mediated enteropathy triggered by exposure to dietary gluten in genetically predisposed individuals. Treatment for CD is to follow, a gluten free diet (GFD). However, some CD patients describe persistent symptoms despite the GFD, suggesting a cross reactivity or specific immune responses against other related-prolamins such as zein present in maize. We evaluated the prevalence of IgA and IgG anti-zein antibodies (AZA) in 37 CD, 375 IBS and 310 healthy controls (HC). All of the IBS subjects met the Rome III criteria and were negative to IgA h-tTG, IgA and IgG Gliadin II. IgA and IgG AZA were measured using an in-house ELISA. Elevated levels of IgA AZA were found in CD patients compared with IBS (p<0.001) and HC (p<0.01). CD patients had the highest prevalence (29.7%) compared with IBS (3.5%) and HC (1.3%) (p<0.0001). IgG AZA production was not demonstrated in any patients or HC. To explore if the results in IBS patients and HC can be explained by cross-reaction among gliadins and zeins, positive serum sample to IgA AZA were analyzed for IgA and IgG antibodies against native Gliadin (AGA). Interestingly, 53.8% of IBS patients and 50.0% of HC got negative results for IgA and IgG AGA, suggesting that IgA AZA response could be specific to maize prolamins. These results open the possibility to explore more about the contribution of the humoral responses to zein in the immunopathogenesis to CD and IBS.