Heat shock protein 60 (HSP60) immunoreactivity in gastric epithelium associated with Helicobacter pylori infection: A pitfall in immunohistochemically interpreting HSP60-mediated autoimmune responses

Previous studies have suggested that heat shock proteins (HSP) of Helicobac ter pylori (H. pylori) are involved in the Induction of autoimmunity mediat ed gastritis, In the present report, the cross-reactivity between H. pylori -related HSP60 and gastric epithelial cells was investigated by the indirec t immunoperoxidase method using two monoclonal antibodies (mAb) against H. pylori derived HSP60, H9 and H20. H9 is reactive with an epitope common to bacterial HSP60, while H20 is specific to H, pylori HSP60. A total of 70 pa raffin-embedded gastric biopsy specimens were analyzed after heat-induced e pitope retrieval. Both mAb were crossreactive with the gastric epithelial c ells, with a higher frequency seen for the HS reactive epitope, The frequen cy of positive epithelial decoration was not significantly different betwee n H. pylori-positive and H. pylori-negative gastric mucosae. A variety of e pithelial and non-epithelial cells were immunostained with mAb H9, while mA b H20 was cross-reactive only with small intestinal epithelia, Reactivity w as mainly located in the Golgi area and rarely in the cytoplasm, These resu lts suggest a noteworthy pitfall in immunohistochemical interpretations of HSP60-associated autoimmune reactions in the gastric mucosa.