B cells pulsed with Helicobacter pylori antigen efficiently activate memory CD8+ T cells from H-pylori-infected individuals

Helicobacter pylori infection causes chronic gastritis that may progress to peptic ulcers or gastric adenocarcinoma and thereby cause major world-wide health problems. Previous studies have shown that CD4(+) T cells are important in the immune response to H. pylori in humans, but the role of CD8(+) T cells is less clear. In order to study the CD8(+) T cell response to H. pylori in greater detail, we have evaluated efficient conditions for activation of CD8(+) T cells in vitro. We show that H. pylori-reactive CD8(+) T cells can be activated most efficiently by B cells or dendritic cells pulsed with H. pylori antigens. We further show that the majority of CD8(+) T cells in H. pylori-infected gastric mucosa are memory cells, and that memory CD8(+) T cells sorted from peripheral blood of H. pylori-infected individuals respond 15-fold more to H. pylori urease compared to memory cells from uninfected subjects. We conclude that CD8(+) T cells do participate in the immune response to H. pylori, and this may have implications for the development of more severe disease outcomes in H. pylori-infected subjects. (c) 2005 Elsevier Inc. All rights reserved.