Helicobacter pylori increases expression of proapoptotic markers Fas and FasL on CD4 lymphocytes in children.

The pathomechanism of Helicobacter pylori action upon gastric mucosa and its role in the pathogenesis of gastritis have not been fully elucidated. The aim of this study was to evaluate the most prevalent lymphocyte subpopulations of the gastric mucosa in gastritis in children, as well as to evaluate the expression of Fas and Fas ligand receptors (FasL), periapoptotic markers of gastric mucosa lymphocytes before and after H. pylori eradication. Forty nine patients aged 6 to 17 years, investigated due to chronic abdominal pain, were studied. The obtained tissue samples were analysed by immunohistochemistry. Different lymphocyte subsets were quantified on the basis of surface antigen expression (CD3, CD4, CD8, CD20), secreted cytokines (IL-4, IL-6, IFNgamma) and Fas and FasL proteins in the gastric mucosa. B and T helper lymphocytes were found to play a major role in the inflammatory infiltration in the gastric mucosa in children during H. pylori infection. Their expression was found to decrease after eradication. The enhanced expression of Fas receptor on lymphocytes before treatment and a decrease of this expression after eradication of H. pylori were shown. It was demonstrated that there is a correlation between CD4 and Fas receptor expression that may induce apoptosis of the helper lymphocytes in infected children.