Increased serum levels of antigliadin antibodies in cystic fibrosis

Usefulness of serum IgG4 in the diagnosis and follow up of autoimmune pancreatitis: A systematic literature review and meta-analysis

High circulating serum immunoglobulin G4 (IgG4) levels have been proposed as a marker of autoimmune pancreatitis (AIP). The aim of the present study was to review the data existing in the English literature on the usefulness of the IgG4 serum levels in the diagnosis and follow up of patients with AIP. A total of 159 patients with AIP and 1099 controls were described in seven selected papers reporting the usefulness of serum IgG4 in diagnosing AIP. In total, 304 controls had pancreatic cancer, 96 had autoimmune diseases, and the remaining 699 had other conditions. The summary receiver-operating characteristic curve analysis was carried out by means of Meta-DiSc open-access software. Serum IgG4 showed good accuracy in distinguishing between AIP and the overall controls, pancreatic cancer and other autoimmune diseases (area under the curve [+/- SE]: 0.920 +/- 0.073, 0.914 +/- 0.191, and 0.949 +/- 0.024, respectively). The studies analyzed showed significantly heterogeneous specificity values in each of the three analyses performed. The analysis of the four studies comparing AIP and pancreatic cancers also showed significantly heterogeneous values of sensitivities and odds ratios. Regarding the usefulness of IgG4 as a marker of efficacy of steroid treatment, a decrease in the serum concentrations of IgG4 was found in the four available studies. The serum IgG4 subclass is a good marker of AIP, and its determination should be included in the diagnostic workup of this disease. However, the heterogeneity of the studies published until now means that more studies are necessary in order to better evaluate the true accuracy of IgG4 in discriminating AIP versus other autoimmune diseases.

Coeliac disease: screened by a new strategy

The incidence of coeliac disease is different throughout Europe. The aim of our study was to investigate its true prevalence using antigliadin and endomysial antibodies in 4615 healthy adults within two different population groups in Northern Italy: 140 were positive for antigliadin antibodies (AGA), 111 only for AGA IgG, 17 for AGA IgA and 12 for IgG and IgA. Of those positive for AGA, nine had an abnormal small-intestine mucosa and were positive for endomysium antibodies (EmA) using the umbilical cord test, a novel methodology. The prevalence, 163/100,000 in the Italian group and 216/100,000 in the German group, is much higher than what was assumed. The positive predictive value of the EmA, confirmed by biopsy, is 100%, that of AGA IgG 2%, of AGA IgA 12% and of the combined AGA IgA and IgG 33%. AGA positive but EmA negative patients displayed normal histological features and distributions of alpha/beta and gamma/delta T-cell receptors on intraepithelial lymphocytes. We can therefore conclude that antigliadin antibodies are not an ideal tool for screening purposes; the umbilical cord EmA test is superior owing to its optimal sensitivity, specificity, high positive predictive value and low cost.