The measurement of IgA and IgG transglutaminase antibodies in celiac disease: A comparison with current diagnostic methods

Celiac disease (CD) is an inflammatory disorder of the small intestine indu ced by cereal prolamins. The demonstration of IgA endomysial antibodies (EM A) is currently the most reliable serological screen for CD. The antigenic target is transglutaminase. The aim of this study was to develop an ELISA a ssay for the detection of antibodies to transglutaminase (TGA), and to asse ss the sensitivity and specificity of TGA for the detection of celiac disea se against the benchmarks of jejunal biopsy, antigliadin antibodies (AGA) a nd EMA. Sera from 57 patients with celiac disease were tested for IgA and I gG TGA, IgA EMA, IgA and IgG AGA, and the total IgA level. The sensitivity, specificity, predictive value and concordance of AGA, EMA and TGA were ass essed against the gold-standard biopsy result. IgG plus IgA TGA offered 100 % sensitivity in CD patients for whom no dietary intervention had been comm enced, with a specificity of 61%. The sensitivity of TGA dropped from 100 t o 79% after dietary restriction. In patients on no gluten restriction, ther e was 100% agreement between TGA and EMA, and 100% agreement between TGA an d AGA for the IgA isotype. The false-positive rate for TGA was 53% in Down' s syndrome patients and 25% in patients with systemic autoimmune disorders. We conclude that testing for TGA is a reliable diagnostic serology for cel iac disease, with improved sensitivity compared with established methods. T he results suggest that serial TGA measurements may be a more accurate mark er for dietary compliance than AGA, but prospective studies are required.