IgA anti-tissue transglutaminase as a diagnostic marker of gluten sensitive enteropathy.

Abstract

Aims-To compare and contrast the sensitivity, specificity, and positive predictive values of IgA antibodies to guinea pig tissue transglutaminase (ELISA), endomysium, and reticulin (immunofluorescence), and gliadin (ELISA), and IgG antibodies to gliadin and tissue transglutaminase. Methods-Sera from 27 newly diagnosed patients with coeliac disease, 65 biopsied gastrointestinal disease controls, and 50 consecutive blood donors were tested. All cases were adults. Results-IgA anti-tissue transglutaminase showed a sensitivity of 85% (23/27 coeliac disease cases seropositive), specificity 97% (2/65 controls and one blood donor showing low titre positivity), and a positive predictive value of 92%. High titre anti-tissue transglutaminase was only seen in coeliac disease. Disease controls with mucosal damage unrelated to gluten enteropathy were IgA anti-tissue transglutaminase negative. Sensitivity, specificity, and positive predictive values for IgA anti-endomysial antibody (monkey oesophagus) were 100%, 100%, and 100%, respectively, and for IgA anti-gliadin, 93%, 95%, and 89%, respectively. Conclusions-Tissue transglutaminase is a major autoantigen in coeliac disease. IgA (but not IgG) anti-tissue transglutaminase, especially when in high titre, is closely associated with coeliac disease, but low titres may not be disease specific. In this small pilot study, the established IgA anti-endomysial assay was the superior test. (J Clin Pathol 1999;52:274-277)

A comparison of 13 guinea pig and human anti-tissue transglutaminase antibody ELISA kits

“…A possible explanation may be the presence of IgA anti-BSA antibodies in some of the non-CD control sera, reacting with the BSA used as a blocking agent in some kits. 10 However, Lock and colleagues 10 did not detect significant IgA anti-BSA antibodies in two disease controls tested, and significant IgA anti-BSA antibodies were not demonstrated in our non-CD controls.…”

“…However, in our study, the two kits in which the use of "calcium activation" of tTG is recorded (Binding Site gpl-tTG kit and Genesis) did not clearly demonstrate superior performance to the other kits. Furthermore, Lock and colleagues 10 found that the addition of calcium to the coating buffer increased both the signal and background values, and therefore produced no overall improvement in the performance of their in house gpl-tTG based IgA tTG ELISA. Nakachi and colleagues 46 also reported that the autoantibody binding sites of tTG were formed in a manner that was essentially calcium independent.…”

The old and new tests for celiac disease: which is the best test combination to diagnose celiac disease in pediatric patients?

“…In the last two decades, the use of anti-tTG antibodies as more accurate markers for CD has largely replaced AGA testing for CD diagnosis (58). Although AGA testing is not recommended by the NASPHAGAN guidelines (30), it could still be considered useful in pediatric patients who test negative for anti-tTG or in IgA-deficient patients (9,25,59,60) because the anti-tTG assay has insufficient sensitivity in very young children.…”

Diagnostic efficacy of the ELISA test for the detection of deamidated anti‐gliadin peptide antibodies in the diagnosis and monitoring of celiac disease

“…The current prevalence of CD in the Western countries is estimated at between 1:80 and 1:100 (16,(20)(21)(22)(23)(24). Identification of anti-tTG and EMA antibodies as a marker for CD has caused AGA to lose the diagnostic role they had held since the early 80s (25). Today, the clinical usefulness of AGA is restricted to specific diagnostic ambits: in the early years of life (possible negativity for anti-tTG), in patients with an IgA deficiency (determination of AGA IgG in association with anti-tTG IgG), and in all cases in which antitTG or EMA antibodies do not give clear results (i.e., borderline values) (26,27).…”