IgA antibodies to jejunum. Specific immunity directed against target organ of gluten-sensitive enteropathy.

Serum IgA antibodies to jejunum (JAB) were found in 78 (96%) of 81 adults and children with untreated celiac disease. Not only did IgA JAB display a significant higher prevalence than IgA antigliadin antibodies (AGA) (72%) in untreated gluten-sensitive enteropathy, but they also allowed us to identify another three celiacs in addition to those detected by IgA antiendomysial antibodies (EmA). Like IgA EmA, IgA JAB persisted at low titer in seven (14%) of 50 celiacs tested after 12 months of gluten-free diet (GFD) despite the regrowth of jejunal villi, whereas IgA AGA disappeared in all these patients consistently with the normalization of intestinal mucosa. IgA JAB and EmA reappearance was close to 100% in the 13 celiacs studied after six months of gluten challenge, while IgA AGA reached the highest prevalence (about 70%) after one month of gluten ingestion without any increase in the following months. All disease and healthy controls were always negative for the three IgA antibodies. Our results prove that IgA JAB and EmA are the best screening tests for active (untreated and on gluten challenge) celiac disease, whereas IgA AGA should be used for monitoring the response to gluten withdrawal. IgA JAB are an expression of a specific immunity directed against the target organ of gluten-sensitive enteropathy, but, before ascribing them a role in the pathogenesis of celiac disease, it should be ascertained whether their production is a primary event leading to jejunal lesions or whether it is a secondary phenomenon due to antigen release from a previously damaged jejunal mucosa.