Antibodies to recombinant human tissue-transglutaminase in coeliac disease: Diagnostic effectiveness and decline pattern after gluten-free diet

Background/aims. To assess the sensitivity and specificity of IgA and I-G tissue-transglutaminase antibodies assay, the pattern of antibody decline after gluten withdrawal and their modifications with reference to dietary compliance. Subjects. We studied sera from 143 untreated coeliac children and adolescents (8.8+/-6.1 years), 212 sera from 97 of those patients after gluten withdrawal, and 64 control subjects with non-coeliac intestinal disorders (6.8+/-4.8 years). Methods. Samples were tested for IgA and IgG class tissue-transglutaminase antibodies by radiobinding assay, using human-derived tissue-transglutaminase, and for IgA anti-endomysium antibodies by indirect immunofluorescence on monkey oesophagus. Results. Untreated coeliac patients had significantly higher titres of I-A and IgG tissue-transglutaminase antibodies than controls (p < 0.00001); the diagnostic sensitivity was 95.8% and 99.3%, respectively, and the specificity was 95.3%. Three patients with selective IgA deficiency were positive for IgG tissue-transglutaminase antibodies. The concordance rate between I-A tissue-transglutaminase antibodies and anti-endomysium antibodies was 98.1%. Patients on gluten-free diet showed a significant decrease in I-A and IgG tissue-transglutaminase antibodies with respect to untreated patients (p < 0.0001). Tissue-transglutaminase was more sensible than anti-endomysium antibodies to detect small amounts of gluten intake when the compliance was poor. Conclusions. The recombinant human tissue-transglutaminase antibodies assay is a highly sensitive and specific test for diagnosis of coeliac disease, and it is useful in monitoring the compliance to gluten-free diet. (C) 2005 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.