Transglutaminases as diagnostically relevant autoantigens in patients with gluten sensitivity.

Background: Patients with gluten sensitivity, i. e. celiac disease and dermatitis herpetiformis have anti-endomysial antibodies recognizing transglutaminases, which are usually detected on appropriate tissue sections. It would be desirable to have available a reliable, tissue-independent serological diagnostic tool. We compared disease-specificity and sensitivity of tTG versus eTG-based detection systems for the diagnosis of anti-endomysial IgA-antibodies.
Patients and Methods: We examined 204 serum samples in duplicates with commercial human ELISA-kits: 54 healthy blood donors, 20 celiac disease, 29 dermatitis herpetiformis and 101 with other autoimmune dermatoses.
Results: The tTG-based ELISA proved to be very disease-specific (100 %) and sensitive for the diagnosis of gluten sensitivity (95 % celiac disease; 96.6 % dermatitis herpetiformis). The eTG-based ELISA was also perfectly specific (100 %), but only 15 % of celiac disease-sera and 44.8 % of dermatitis herpetiformis-sera yielded positive results.
Conclusions: The human tTG-ELISA fulfills all criteria of a screening test and, because of being investigator-independent, inexpensive and highly reproducible, compares favorably with the current diagnostic gold standard (indirect immunofluorescence and biopsy) of celiac disease and dermatitis herpetiformis. The low sensitivity of the eTG-ELISA may have technical reasons, but could theoretically also be linked to disease activity or indicate the existence of an as yet undefined disease subset. Studies are currently under way to address these issues.