Serological tests for coeliac disease-specific antibodies showed exceptionally high sensitivity and specificity in a Tunisian cohort, underscoring their diagnostic utility. The recently published findings stem from a collaborative study between Euroimmun and various laboratories in Tunisia.
Studying a unique population
Coeliac disease is an autoimmune disorder triggered in genetically predisposed individuals by gluten ingestion. It causes inflammation and damage to the small intestine lining, leading to nutrient malabsorption and a range of gastrointestinal and extraintestinal symptoms. In Tunisia, diagnosis of coeliac disease often relies on small intestine biopsy, which is invasive and burdensome for patients. Serological tests could serve as effective, non-invasive screening tools that could potentially reduce the reliance on biopsies.
Tunisia’s population is characterised by remarkable genetic heterogenicity, reflecting its history of migration, including from Europe, Sub-Saharan Africa and Asia. This genetic diversity makes it a valuable population for studying health conditions and evaluating diagnostic techniques. The present research sought to assess how different serological assays perform in this unique demographic context.
Consistent results across assays
The study compared the performance of indirect immunofluorescence assay (IFA), ELISA and immunoblot in detecting diagnostically relevant antibodies in serum samples from 80 coeliac disease patients and 158 appropriate controls.
In IFA performed on primate liver (Euroimmun) and umbilical cord (in-house) substrates, all coeliac disease patients and none of the controls were positive for anti-endomysium IgA autoantibodies, demonstrating the high sensitivity and specificity of this method. Similarly, all coeliac disease patients and none of the controls were positive in anti-transglutaminase (tTG) IgA ELISA. Analysis of IgA and IgG antibodies against deamidated gliadin peptides (DGP) using Euroimmun ELISAs based on the designer antigen GAF-3X also showed 100 % sensitivity and 100 % specificity.
In addition, EUROLINE immunoblots (Euroimmun) were used to simultaneously investigate various antibodies associated with gastrointestinal diseases. In the coeliac cohort, positivity rates for key coeliac disease-specific antibodies were: 99 % for tTG IgA, 94 % for GAF-3X IgA and 85 % for GAF-3X IgG. Notably, a proportion of patients also exhibited antibodies against Saccharomyces cerevisiae (IgA 31 %; IgG 43 %), with minimal reactivity observed in controls. Antibodies against parietal cells (IgG 25 %) were also present in a subset of coeliac patients. This could potentially indicate coexisting autoimmune diseases that may warrant targeted follow-up.
Outlook for clinical practice
Overall, the study demonstrated robust and consistent performance of coeliac disease-specific serological assays in the Tunisian cohort, with high concordance between markers and across multiple platforms. These tests could play a crucial role in coeliac disease diagnostics in this population and reduce the need for invasive biopsies. The findings align with the growing body of evidence supporting non-invasive diagnostics of coeliac disease.
Read the full study in Frontiers in Gastroenterology:
