In general, a balanced Th1/Th2 immune response is found in the majority of cases with non-atrophic chronic gastritis, while a prevalent Th2 immune response, mediated by IL-13 secreting cells, is observed in patients with intestinal metaplasia and intestinal-type gastric cancer [38], indicating that a shift from Th1 to Th2 immune response, and in particular IL-13 secretion, may be involved in the different outcomes of H. pylori infection and its progression towards carcinogenesis. This evidence concerns the gene IL13 and chronic atrophic gastritis.