Anti-transglutaminase antibodies and the serological diagnosis of coeliac disease

Abstract

Tissue transglutaminase (tTG) has recently been identified as the antigenic target recognised by anti-endomysial antibodies in patients with coeliac disease. In this study, an enzyme-linked immunosorbent assay (ELISA) is used to measure IgA, IgG and IgM antibodies to tTG in patients with coeliac disease and a variety of other inflammatory disorders; and is compared to the standard immunofluorescence test used to detect endomysial antibodies (EMA). In the samples tested, 3% control sera (n=146), 83% EMA-positive sera (n=29), 9% patients with Graves' disease (n=94), 12% antimitochondrial antibody-positive sera (n=53), 11% rheumatoid arthritis patients (n=53) and 22% systemic lupus erythematosus (SLE) patients (n=46) were positive for anti-tTG antibodies. In contrast, none of the controls, 1% of patients with Graves' disease, 2% antimitochondrial antibody-positive sera, 2% rheumatoid arthritis patients and none of the SLE patients were positive for EMA. Measurement of IgG or IgM antibodies to tTG was much less reliable than IgA anti-tTG antibody for the serological diagnosis of coeliac disease. The addition of calcium to the coating buffer improved the assay characteristics of the anti-tTG ELISA. However, the IgA anti-tTG ELISA, with and without calcium, performed less well than the standard EMA test used for the serological diagnosis of coeliac disease. In particular, the anti-tTG ELISA gave a higher rate of non-specific positive reactions.

Calcium activation of tissue transglutaminase in radioligand binding and enzyme-linked autoantibody immunoassays in childhood celiac disease

“…Indeed, our present results strengthen this view for ELISA also in children with CD. Similar results have been reported from other laboratories [9,20,21]. However, another group did not observe this calcium effect [22].…”

“…Similar findings have been reported by others [9,20,21], but not by all laboratories [22]. Unfortunately, the available information about the presence of calcium in the commercial kits is limited [12].…”

Quality not quantity for transglutaminase antibody 2: the performance of an endomysial and tissue transglutaminase test in screening coeliac disease remains stable over time

“…The corollary is that TG2 strategies result in false positivity far in excess of the size of the false negative cohort, even when confirmatory testing is applied to the lesser degrees of TG2 titres. False positivity is not only seen in our cohort, but is well documented in the literature [3,6,[12][13][14][15][16][17][18][19][20][21][22][23][24]. In the absence of standardization between assays there is no possibility of selecting a single threshold recommendation for reflex second-test use, which is applicable to all test variants.…”

Immunoglobulin G (IgG) Anti-Tissue Transglutaminase Antibodies Used as Markers for IgA-Deficient Celiac Disease Patients

“…However, IgA-deficient CoD patients are not identified by conventional IgA serology, and inconsistent results concerning the diagnostic validity of IgG-EmA and IgG-tTG in different patient groups have been reported (14,20,31).…”

“…IgG-EmA detection in IgA-deficient patients was equivalent to the IgA-EmA detection in subjects with normal serum IgA levels, despite the technical difficulties and subjective means of titer assessment associated with the immunofluorescence method (19,20). IgG-tTG measurement by an enzyme-linked immunosorbent assay (ELISA) based on guinea pig transglutaminase, on the other hand, has limited relevance for CoD (14,31). However, it has recently been shown that the detection of IgG-tTG with recombinant human tTG of high purity was a useful marker for CoD in IgA-deficient subjects (18).…”