Tetramer test aids celiac disease identification in gluten-free eaters
MedWire News: Norwegian research findings suggest that a HLA-DQ2-gliadin peptide tetramer test detects celiac disease with greater sensitivity than duodenal biopsy in individuals on a gluten-free diet (GFD).
"Our results have implications for how to evaluate clinically gluten-intolerant patients that have started a GFD without diagnosis," comment the researchers in the American Journal of Gastroenterology.
They add: "Many of these individuals start a GFD without proper diagnostic procedures, and therefore the diagnosis may be missed [altogether]... as both the serology and small intestinal pathology normalizes in celiac disease patients when they start a GFD."
In the study, 13 HLA-DQ2+ individuals with a previous diagnosis of celiac disease and who had been on a GFD for at least 4 weeks, underwent a gluten challenge in which they consumed four slices of gluten-containing bread per day, for 3 days.
Duodenal mucosal biopsies and blood samples were taken from all participants prior to and immediately after the gluten challenge.
All biopsies were graded according to Marsh criteria (type 0=normal, 1=lymphocytic infiltration, 2=hyperplasia, and type 3a, b, or c=increasing degree of destruction), and blood samples were analyzed for the presence of HLA-DQ2-gliadin peptide tetramers as an indicator of celiac disease-specific T cells.
Margit Brottveit (Oslo University Hospital) and team report that postchallenge, the tetramer test correctly diagnosed celiac disease more often than biopsy, at a rate of 85% versus 31%.
Furthermore, two disease-free controls were found to have normal mucosal histology and negative tetramer staining for gluten-specific T cells.
Acknowledging that many individuals in the general population start a GFD without an actual diagnosis of celiac disease, the team investigated the true incidence of celiac among a group of such individuals (n=35) who underwent the aforementioned gluten challenge.
In doing so, they found that only three of these patients had a positive biopsy or tetramer-based diagnosis of celiac disease.
One patient had a histological score of Marsh 2, two had a Marsh 3b score, and two also had a positive tetramer test.
This, say the researchers, illustrates that surprisingly few (10%) Norwegian individuals with self-prescribed GFD actually have CD.
The researchers conclude that although the tetramer test boasts high diagnostic sensitivity, it "is quite laborious and the tetramer reagents have limited stability, [thus] widespread use of the test is hardly probable."
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By Lauretta Ihonor