Endomysial antibody-negative coeliac disease: clinical characteristics and intestinal autoantibody deposits. [Gut] Journal article

BACKGROUND: Some untreated coeliac disease patients are negative for serum endomysial autoantibodies (EmA) targeted against transglutaminase 2 (TG2).
AIMS: To evaluate the clinical and histological features of EmA-negative coeliac disease, and to examine whether EmA-equivalent autoantibodies against TG2 can be demonstrated in the small bowel mucosa when absent in serum.
PATIENTS: Serum EmA was studied in 177 biopsy- proven adult coeliac disease patients. Twenty patients with intestinal diseases served as non-coeliac controls; three had autoimmune enteropathy with villous atrophy.
METHODS: Clinical manifestations, small bowel mucosal morphology, intraepithelial inflammation and TG2- specific extracellular IgA deposits were investigated in both serum EmA-negative and EmA-positive patients.
RESULTS: Twenty-two IgA-competent coeliac disease patients were negative for serum EmA. Three of these had small bowel lymphoma. EmA-negative coeliac disease patients were older, had abdominal symptoms more often, and in their intestinal mucosa the density of gamma& [delta]+ IELs was lower than in EmA-positive patients; otherwise the histology was similar. All, also serum EmA- negative, coeliac disease patients, but none of the disease controls had gluten-dependent mucosal IgA deposits alongside TG2 in the small bowel mucosal specimens. In vivo deposited IgA was shown to be TG2- specific by its ability to bind recombinant TG2.
CONCLUSIONS: Negative serum EmA might be associated with advanced coeliac disease. TG2-targeted autoantibodies were deposited in the small bowel mucosa even when absent in serum. This finding can be utilized in the diagnosis of seronegative coeliac disease when the histology is equivocal. It also seems to be helpful in differential diagnosis between autoimmune enteropathy and coeliac disease.

Gut