A new double immunohistochemistry method to detect mucosal anti-transglutaminase IgA deposits in coeliac children

Background: Intestinal transglutaminase (TG2) IgA deposits represent early marker of coeliac disease (CeD) and can predict the evolution towards intestinal atrophy. Aims: To validate a double immunohistochemistry method for the determination of intestinal TG2 IgA deposits on formalin-fixed paraffin-embedded biopsies. Methods: Immunohistochemistry was tested on: 1) children with overt CeD [persistently positive serum IgA anti-tissue transglutaminase type 2 (TGA-IgA) with moderate or low titer, and histological findings of CeD]; 2) potential CeD (persistently positive serum TGA-IgA and normal intestinal mucosa) and 3) controls (negative serum TGA-IgA and normal intestinal mucosa). Results: Samples from 61 children were analyzed (32 overt CeD, 14 potential CeD, and 15 controls). Deposits appeared as focal, multifocal, or confluent extracellular foci of red and brown staining colocalization in the sub-epithelium and around mucosal vessels. Deposits were present in all 32 children with overt CeD and in 9/14 potential CeD. Deposits were never observed in the 15 controls. Patients with higher serum level of TGA-IgA and with mucosal atrophy showed mostly a multifocal/diffuse pattern of deposits distribution. The bulb appeared most severely involved. In potential CeD deposits showed mainly a focal distribution. Conclusion: Our results indicate double immunohistochemistry as promising diagnostic tool to improve diagnosis of CeD.