Enterocyte actin autoantibody detection: a new diagnostic tool in celiac disease diagnosis: results of a multicenter study.

Objectives. This study describes a new method to detect autoantibodies against actin filaments (AAA) as a serological marker of intestinal villous atrophy (IVA) in celiac disease (CD), and reports the results of an Italian double-blind multicenter study. Methods. IgA-AAA were analysed by immunofluorescence using a newly developed method based on intestinal epithelial cells cultured in presence of colchicine. IgA-AAA were blindly evaluated prospectively in 223 anti-endomysial antibody (AEA) and/or anti- transglutaminase antibody (TGA) positive subjects and in 78 AEA and TGA negative subjects. IgA-AAA positive patients underwent an intestinal biopsy to confirm the diagnosis. Moreover, IgA-AAA were retrospectively investigated in 84 biopsy-proven CD patients and in 2000 new consecutively collected serum samples from AEA and TGA negative non-biopsied subjects. Results. IgA-AAA were positive in 98.2% of the CD patients with flat mucosa, in 89% with subtotal villous atrophy, and in 30% with partial villous atrophy. IgA-AAA were present in none of the AEA and TGA negative non-biopsied controls. In AEA and/or TGA positive CD patients IgA- AAA positivity significantly correlated with IVA (p<0.000 in the prospective study, p=0.005 in the retrospective study). In the prospective study, the values of sensitivity, specificity, the positive predictive value, the negative predictive value and the efficiency of the IgA-AAA test to identify patients with IVA were, respectively, 83.9%, 95.1%, 97.8%, 69.2%, and 87.0%. Furthermore, a significant correlation (p<0.0001) was found between the IgA-AAA serum titre and the degree of IVA (rs 0.56). Conclusions. The results of this multicenter study show that the new method for IgA-AAA detection could represent a practical diagnostic tool in AEA and/or TGA positive subjects, which would be especially useful when IVA shows a patchy distribution, when the histological picture is difficult to interpret, or when a biopsy could represent a life-threatening risk.