Tissue transglutaminase expression in celiac mucosa: an immunohistochemical study.

Tissue transglutaminase (tTG) constitutes the main autoantigen in celiac disease (CD). The aim of the study was to clarify weather celiac disease is associated with changes in tTG expression in duodenal mucosa. Tissue transglutaminase was assessed immunohistochemically (clone CUB 7402) in duodenal biopsy specimens from 22 untreated CD patients, ten normal controls (NC) with unremarkable duodenal mucosa, and nine disease nonceliac controls (DC). In 15 CD patients duodenal biopsy specimens were repeatedly assessed after these patients had been prescribed gluten-free diet. Positive pixel count algorithm of ImageScope was used for quantitative evaluation of immunohistochemistry. Tissue transglutaminase expression in superficial epithelium differed significantly between the three groups (p < 0.001). It was increased in DC in relation to NC (p < 0.001) and in CD--in relation to NC (p < 0.001) and DC (p = 0.003). In CD and DC, cryptal epithelium was stained more intensively than in NC (p < 0.001), but there was no difference between CD and DC (p = 0.507). The same pattern was seen in lamina propria. A significant decrease in tTG expression in all the compartments was seen in repeatedly assessed samples. Untreated CD is associated with tTG overexpression, which is reversible. Tissue transglutaminase up-regulation does not seem to be specific for CD and can appear in other pathological conditions.