title: Immunoglobulin G (IgG) anti-tissue transglutaminase antibodies used as markers for IgA-deficient celiac disease patients.
abstract: The role of immunoglobulin A (IgA) anti-tissue transglutaminase antibodies (IgA-tTG) as predictors of untreated celiac disease (CoD) is well documented, and the presence and levels of these antibodies are most accurately monitored with native or recombinant human antigens. However, IgA-deficient CoD patients are not identified by IgA serology, and conflicting results concerning the diagnostic validity of IgG antibodies against gliadin (IgG-AGA), endomysium (IgG-EmA), and tTG (IgG-tTG) have been reported. The aim of the present study was to evaluate the utility of IgG-tTG for the detection of CoD in IgA-deficient patients. Samples from 115 IgA-deficient and 200 IgA-sufficient subjects were collected and tested for the presence of IgA and IgG antibodies against tTG, EmA, and AGA. Antibodies against tTG were measured by an enzyme-linked immunosorbent assay based on recombinant human tTG, and antibodies against EmA were determined by immunofluorescence. The values for IgG-tTG showed a higher correlation (correlation coefficient [r] = 0.91) with those for IgG-EmA for the IgA-deficient subjects than for the IgA-sufficient subjects (r = 0.88). The overall concordance of the positive and negative results between IgG-tTG and IgG-EmA was 97%, and the IgG-tTG assay discriminated between IgG-EmA-positive and -negative subjects with IgA deficiency at a rate of 100%. Elevated levels of IgG-tTG and IgG-EmA were measured in 70% of the IgA-sufficient subjects. IgG-tTG detection with recombinant human tTG is a good alternative to IgG-EmA detection, and the addition of IgG-tTG assessment to present screening methods may improve the ability to identify IgA-deficient subjects with CoD.
authors.affiliation: Pharmacia Diagnostics AB, Rapsgatan 7, SE-751 82 Uppsala, Sweden. ingrid.dahlbom@diagnostics.com
authors.forename: Ingrid
authors.initials: I
authors.lastname: Dahlbom
authors.forename: Martin
authors.initials: M
authors.lastname: Olsson
authors.forename: Nahal Kazemi
authors.initials: NK
authors.lastname: Forooz
authors.forename: Anders G
authors.initials: AG
authors.lastname: Sjöholm
authors.forename: Lennart
authors.initials: L
authors.lastname: Truedsson
authors.forename: Tony
authors.initials: T
authors.lastname: Hansson
mesh_terms: D015415:Biomarkers / Q000097:blood; D002446:Celiac Disease / Q000175:diagnosis* / Q000276:immunology; D006801:Humans; D017098:IgA Deficiency / Q000150:complications*; D007074:Immunoglobulin G / Q000097:blood* / Q000276:immunology; D011503:Transglutaminases / Q000276:immunology*
chemical_list: D015415:Biomarkers; D007074:Immunoglobulin G; D011503:Transglutaminases