Antibody detection by agglutination-PCR (ADAP) assays for the analysis of tissue transglutaminase autoantibodies in celiac disease

Abstract

Background & aims: Tissue transglutaminase autoantibodies (tTGA) are used as diagnostic markers of celiac disease. Different methods have been developed for the detection of tTGA of which enzyme-linked immunosorbent assays (ELISA), radiobinding assays (RBA) and electrochemiluminescence (ECL) assays are the most commonly used. Here we aimed to evaluate a novel antibody detection by agglutination-PCR (ADAP) assay for the detection of tTGA. Methods: Included were 126 children with untreated celiac disease (UCD), 64 disease controls (DC), 21 children with potential celiac disease (PCD), and 1501 children from the general population. Tissue TGA were determined using an automated ADAP assay platform and compared with two RBAs for the detection of IgA-tTG and IgG-tTG, respectively. Results: ADAP detected tTGA in 123/126 (97.6%) UCD children compared with 122/126 (96.8%) using RBA-IgA-tTG and RBA-IgG-tTG (p > 0.9999), respectively. Among DC, ADAP detected 5/64 (7.8%) children with tTGA compared with 4/64 (6.3%) with RBA-IgA-tTG (p > 0.9999) and 8/64 (12.5%) with RBA-IgG-tTG (p = 0.5600), respectively. Tissue TGAs were equally detected in children with PCD in both assays. In the general population, 4/1501 (0.3%) were tTGA positive using ADAP compared with 3/1501 (0.2%) for RBA-IgA-tTG and RBA-IgG-tTG (p > 0.9999), respectively. The area under the curves (AUCs) were 0.998 for ADAP, 0.994 for RBA-IgA-tTG, and 0.999 for RBA-IgG-tTG, respectively. Conclusions: No difference in specificity and sensitivity of tTGA for the diagnosis of celiac disease was reported between ADAP and RBA. ADAP could be recommended as the first-line screening method of larger populations for celiac disease.