[Immune response to an H. pylori infection in the stomach]

Helicobacter pylori infection associates with chronic infiltration by various cell types including T cells whose cytokine production may regulate local immune response to the bacterium. Indeed in the antral biopsy tissue taken from both H. pylori infected and uninfected stomach, CD3 positive T cells predominate over neutrophils, monocytes and plasma cells. Depending on the rout of antigen priming, these tissue infiltrating T cells play roles either as effector cells of tissue damage or as protecting cells to H. pylori challenge. Emerging evidences suggests that H. pylori infection appear to direct regional immune response to a Th1 type. However, even in the absence of H. pylori infection, almost ninety percent of gastric CD4 T cells are comprised of IFN-gamma producing cells. Therefore activation of tissue infiltrating T cells, either by antigen specific and non-specific manner, would lead to a perpetual inflammation in the H. pylori infected stomach.