The determination of antibodies against endomysium, gliadin and tissue transglutaminase serves in the serological diagnosis of gluten-sensitive enteropathy (coeliac disease, non-tropical sprue) and Duhring’s dermatitis herpetiformis (DDH). Coeliac disease is an autoimmune disease which occurs in predisposed individuals as a reaction to gluten sensitivity. Gluten is found in various cereals (e.g. wheat, barley, rye). It consists of a mixture of proteins, which can be divided into two groups: prolamins and glutelins, with gliadin being the most frequent prolamin. An extensive immune reaction is triggered, causing pathological tissue changes, particularly damage to the mucous membranes of the small intestine. Components of this immune reaction are antibodies against endomysium or tTG and against the deamidated gliadin generated by tTG. The frequency of diagnosed coeliac disease amounts to around 1:300 in western Ireland, Italy, the USA, the Middle East, India and Cuba, around 1:1,000 in Germany and Austria and around 1:2,000 to 1:4,500 in other European countries. The clinical symptoms comprise fatigue (78%), borborygmus (72%), abdominal pain (64%), diarrhoea (56%), effects of malabsorption (44%) with weight loss, anaemia and growth retardation in children, vomiting (16 %), constipation (12 %) and bone pains (12 %). Some patients with gluten-sensitive enteropathy also suffer from Duhring's dermatitis herpetiformis (10 %), a chronic skin disease accompanied by the formation of blisters. In a prolonged course, mainly in adults, the risk of melanoma, particularly intestinal T-cell lymphoma, is about 10 %.

The serological determination of IgA and IgG antibodies against GAF-3X and endomysium (tissue transglutaminase) is useful for the diagnosis of coeliac disease and Duhring’s dermatitis herpetiformis, coeliac disease with splenic hypofunction and subclinical coeliac disease in women with repeated fetus loss during the first trimester and for the clarification of gluten ataxia. Furthermore, it has been observed that a selective IgA antibody deficiency is associated with a very high titer of class IgG anti-tissue transglutaminase. During the course of therapy by means of a gluten-free diet, the concentration of IgA antibodies against gliadin falls more rapidly and against tissue transglutaminase more slowly to a low value within a few months. Permanently elevated antibody levels are indicative of non-compliance with a gluten-free diet.