Mucosal lymphocyte subsets and HLA‐DR antigen expression in paediatric Helicobacter pylori ‐associated gastritis

Summary Paediatric studies may provide important insights into the immunopathology of Helicobacter pylori ‐associated gastritis, as mucosal changes reflect different stages of the immunoinflammatory response. We characterized, by quantitative immunohistochemistry, gastric mucosal lymphocyte phenotype and HLA‐DR antigen expression and evaluated correlation with histopathology, in H. pylori‐ infected (Hp+ve) and uninfected children (Hp–ve). In the infected group, lamina propria CD3+ and IgA plasmocyte cell numbers were significantly higher and a trend for predominance of CD8+ over CD4+ was observed both in epithelium and lamina propria. A correlation of inflammation score with lamina propria CD3+ and CD4+ cell numbers and of CD45RO+ T lymphocytes with density of colonization was observed. The proportion of epithelial cells expressing HLA‐DR antigen was significantly higher in the Hp+ve group and furthermore, glandular HLA‐DR expression correlated with lamina propria CD3+ cell numbers, emphasizing the potential role of epithelial cells as antigen‐presenting cells at this stage of infection.