A novel quantitative ELISA as accurate and reproducible tool to detect epidermal transglutaminase antibodies in patients with Dermatitis Herpetiformis

Background: Dermatitis Herpetiformis (DH) diagnosis relies on direct immunofluorescence (DIF) on skin biopsy. Serology for anti-epidermal transglutaminase antibodies (Anti-TG3 Abs) has attracted interest, being inexpensive and less invasive. However, the available test has variable sensitivity and low specificity in Coeliac Disease (CD) patients without DH. Objective: To evaluate the diagnostic accuracy and reproducibility of a novel quantitative ELISA for the measurement of Anti-TG3 Abs. Methods: ELISA was set-up with recombinant TG3 and a standard curve based on a human recombinant monoclonal IgA anti-TG3. Sera of 57 DH patients, 212 CD patients, 120 patients with non-gluten related gastrointestinal diseases (CTRL) and 168 healthy controls (HC) were tested. Results: The test was reproducible with high sensitivity (91%). Test specificity was high when considering HC (99%) as well as CTRL (98%). Interestingly in CD patients test specificity was agedependent and was higher (97%) in patients ≤ 25 years of age. Limitations: Not all DH were confirmed by DIF. Conclusion: The ELISA test could be used as a screening tool when DH is clinically suspected and may serve as a sole diagnostic test in younger patients. The quantification of Anti-TG3 Abs levels will facilitate the comparison of results from different laboratories.