Extraction of IgE-binding components of Helicobacter pylori by immunoblotting analysis in chronic urticaria patients

Background. An association between Helicobacter pylori and chronic urticaria has been suspected previously. An IgE-mediated pathway might be a possible link between H. pylori infection and chronic urticaria, and therefore we wanted to prepare an optimal H. pylori antigen to detect H. pylori-specific IgE antibodies in chronic urticaria patients. Methods: H. pylori antigen extracts were prepared in different ways to find the optimal antigen extract to be used in the assays. Immunoblotting was used to detect IgE-binding bands. The results were applied in an H. pylori RAST assay for specific H. pylori IgE antibodies in patient sera. Results: In immunoblotting, the largest number of IgE-stained bands were visualized in the washing fluids and sonicated extracts, while strong heating and denaturing treatments destroyed the epitopes for IgE binding, suggesting that they belonged to the flagellar structures of H. pylori. However, in H. pylori-specific RAST analysis, specific IgE was found only in 1 of 25 H. pylori-infected patients. Conclusions: Our findings suggest that although IgE-binding epitopes were found in H. pylori, H. pylori-specific IgE antibodies are not common in chronic urticaria, and the clinical significance of the IgE response is unclear. Copyright (C) 2001 S. Karger AG, Basel.