Small Bowel Transglutaminase 2-specific IgA Deposits in Dermatitis Herpetiformis
Teea T. Salmi, Kaisa Hervonen, Kaija Laurila, Pekka Collin, Markku Mäki, Outi Koskinen, Heini Huhtala, Katri Kaukinen, Timo Reunala
Dermatitis herpetiformis (DH) is an extraintestinal manifestation of coeliac disease. Untreated coeliac disease patients are known to have transglutaminase 2 (TG2)-targeted IgA deposits in the small bowel mucosa. To evaluate whether similar intestinal IgA deposits are also present in DH and whether the deposits disappear with gluten-free diet, 47 untreated and 27 treated DH patients were studied. Seventy-nine percent of untreated and 41% of the treated DH patients had TG2-specific IgA deposits in the small bowel, and the presence of the deposits showed a significant association with the degree of small bowel villous atrophy (p < 0.001). Other coeliac-disease related inflammatory markers were also investigated, and the density of small bowel mucosal intraepithelial γδ+ T cells was increased in 91% of untreated and 73% of treated DH patients. The results show that the majority of untreated DH patients have similar gluten-dependent TG2-specific IgA deposits the small bowel mucosa as coeliac disease patients.