IgG1 antiendomysium and IgG antitissue transglutaminase (anti-tTG) antibodies in coeliac patients with selective IgA deficiency

Open Access
Publisher Website
Google Scholar
Abstract
BACKGROUND In selective IgA deficiency (IgAD), there is no reliable screening test for coeliac disease (CD). AIM To evaluate the usefulness of IgG1 antiendomysium and IgG antitissue transglutaminase tests for CD diagnosis in IgAD. METHODS IgA and IgG antigliadin antibodies (IgA- and IgG-AGA), IgA and IgG1antiendomysium antibodies (IgA- and IgG1-EMA), and IgA and IgG antitissue transglutaminase (IgA- and IgG-anti-tTG) were assayed in: (a) 20 untreated IgAD/CD patients; (b) 34 IgAD/CD patients on a strict gluten free diet (GFD); (c) 10 IgAD/CD patients not on a strict GFD; (d) 11 untreated CD patients without IgAD; (e) 10 healthy IgAD patients; and (f) 25 healthy controls. RESULTS In all untreated IgAD/CD patients, IgG1-EMA, IgG-anti-tTG, and IgG-AGA were positive whereas IgA antibodies against these antigens were negative. IgAD/CD patients on a strict GFD did not produce IgG-AGA or IgG1-EMA but four of 34 produced IgG anti-tTG. IgAD/CD subjects not on a strict GFD produced IgG-AGA whereas 5/10 and 4/10 were IgG1- EMA and IgG-anti-tTG negative, respectively. Untreated CD patients without IgAD were AGA (IgA and IgG), EMA (IgA and IgG1), and anti-tTG (IgA and IgG) positive. Healthy controls were AGA and EMA negative whereas two of 10 apparently healthy IgAD subjects and one of 25 healthy negative control were IgG-anti-tTG positive. CONCLUSIONS Both IgG1-EMA and IgG-anti-tTG tests appear to be useful for identification of IgAD/CD patients whereas they are less satisfactory for monitoring dietary compliance in these subjects. In addition, our findings seem to suggest that IgG-EMA autoantibodies produced by coeliac patients are mainly of the IgG1 subtype.