Systemic and local immune responses againstHelicobacter pylori urease in patients with chronic gastritis: distinct IgA and IgG productive sites

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Abstract
Background—Helicobacter pylori urease is a major target for immune responses among various bacterial components in H pyloriinfected patients.Aims—To analyse the relation between systemic and local humoral immune responses toH pylori urease and grades of chronic gastritis.Patients—Seventy five patients with chronic gastritis associated with H pyloriinfection were classified into three groups (grade I, superficial gastritis; II, atrophic gastritis, quiescent; or III, atrophic gastritis, active).Methods—Anti-H pylori urease specific antibodies in the serum, gastric juice, and biopsy specimens were determined by ELISA or western blotting analysis. The sites for H pylori urease and its specific antibody producing B lymphocytes were confirmed by immunohistochemical analysis.Results—In the sera of patients with grade I gastritis, weak IgG but relatively strong IgA responses toH pylori urease were observed; dominant strong IgG responses were detected in grade II gastritis. In grade III gastritis, significant IgG and IgA responses were obtained. A similar pattern of IgA and IgG responses was detected in gastric juice and tissue. H pylori urease specific, antibody producing B cells were not found in the gastric mucosa of patients with grade I gastritis despite the presence of such B cells in the duodenal bulb. Specific B cells were observed in the gastric mucosa of patients with grade II and III gastritis with atrophy.Conclusions—PurifiedH pylori urease, together with localisation of its specific antibody producing B cells, are useful for serological testing and histopathological analysis for determining the stage of chronic gastritis and studying the pathogenesis ofH pylori infection.