Identification of a new coeliac disease subgroup: antiendomysial and anti-transglutaminase antibodies of IgG class in the absence of selective IgA deficiency

Abstract. Picarelli A, Di Tola M, Sabbatella L,Mastracchio A, Trecca A, Gabrielli F, Di Cello T,Anania MC, Torsoli A (University of Rome ‘‘LaSapienza’’, Rome, Italy). Identification of a newcoeliac disease subgroup: antiendomysial and anti-transglutaminase antibodies of IgG class in theabsence of selective IgA deficiency. J Intern Med2001; 249: 181–188.Objective. The aim of the present study was toincrease the sensitivity of the antiendomysial anti-body (EMA) test by evaluating also EMAs of IgG1isotype.Design and subjects. Over the last 2 years, serumEMAs IgA and IgG1 were determined in 1399patients, referred to our gastrointestinal unit due toclinical suspicion of malabsorption. Serum anti-tissue transglutaminase (tTG) antibodies IgA andIgG, as well as total IgA levels, were also investigated.Furthermore, EMAs IgA and IgG1 were evaluated inbiopsy culture supernatants. Biopsy specimens werealso admitted to histological and immunohistochem-ical evaluation. Twenty-six patients with gastroente-rological disease other than coeliac disease (CD) wereused as a disease control group. Ninety-nine blooddonors were used as a healthy control group.Results. Diagnosis of CD was based on histologicalfindings in the 110/1399 patients showing EMAIgA positivity, and in a further 56/1399 patientspresenting both EMA IgA and IgG1 positivity in seraas well as in culture supernatants. Of the remaining1233 EMA IgA-negative patients, 60 showed onlyEMA IgG1 positivity both in sera and in culturesupernatants. It is noteworthy that anti-tissuetransglutaminase antibodies IgG (anti-tTG) werepositive in all 60 EMA IgG1-positive patients aswell. By contrast, a selective IgA deficiency wasfound in only 11 out of the 60 EMA IgG1-positivepatients. Villous height/crypt depth ratio was < 3:1in 38 of the 60 EMA IgG1-positive patients (63.3%),whilst overexpression of ICAM-1 and CD25 wasobserved in all these patients.Conclusions. In this study, we observed a group ofCD patients who were EMA IgG1-positive even inthe absence of EMA IgA positivity and IgA defici-ency. The diagnosis was based on the finding of thegluten-dependent clinical and histological featurestypical of CD. Data emerging from the presentinvestigation thus suggest that the prevalence ofCD should be reassessed and that the determinationof EMA IgG1 could offer a new tool in the diagnosticarmamentarium of CD.Keywords: coeliac disease, antiendomysial antibod-ies, IgG isotype, tissue transglutaminase.