A new dot immunoassay for simultaneous detection of celiac specific antibodies and IgA-deficiency

Background: This study investigated whether a dot immunoassay (DIA) can provide simultaneous detection of anti-tissue transglutaminase (tTG), anti-deamidated gliadin (DG) and total IgA antibodies, as required in the work-up of celiac disease (CD) patients. Methods: Celiac disease patients (n=111) consecutively diagnosed from 2001 to 2011 at the Children's Hospital and Institute of Immunology (Technical University Dresden) were tested for anti-tTG, anti-DG and total IgA by enzyme-linked immunosorbent assay (ELISA) and DIA retrospectively. Blood donors (n=45) and non-CD individuals with low IgA serum levels (n=8) were included as controls. Antibodies to endomysial antigens (EmA) were assessed by indirect immunofluorescence (IIF). Results: Four (3.6%) of 111 CD patients demonstrated an IgA deficiency with total IgA below 50 mg/L by ELISA. Total IgA of the 107 IgA-non-deficient CD patients varied from 70 to 6000 mg/L. All four IgA-deficient CD patients were detected by a reduced reaction control of DIA and demonstrated positive anti-tTG or anti-DG IgG by DIA or ELISA. Detection of anti-tTG and anti-DG by DIA and ELISA showed a very good agreement (IgA: kappa=0.972, 0.856, respectively; IgG: 0.921, 0.895, respectively). Conclusions: Immunodot assay is a reliable and easy-to-use technique for the detection of IgA-deficient CD patients. Simultaneous assessment of anti-tTG and anti-DG IgA antibodies, and IgA deficiency by DIA can improve the efficacy of CD serology.