title: Helicobacter pylori polyclonally activates murine CD4(+) T cells in the absence of antigen-presenting cells.
abstract: Helicobacter pylori is a Gram-negative bacterium that causes a variety of gastrointestinal diseases, such as duodenal ulcer and gastric carcinoma. The T cell response against H. pylori is thought to contribute to the pathogenesis of these diseases. Here, we show that mouse-adapted H. pylori is able to polyclonally activate murine CD4(+) T lymphocytes, irrespective of their antigen specificity. Murine T helper cell clones as well as short-term cultured, polyclonal Th1 and Th2 cell lines and a human T cell clone, but not naive CD4(+) T cells, could be activated in this manner. The effect was independent of antigen-presenting cells and required direct contact between H. pylori and T cells. Only whole cells of H. pylori, but not lysates or sonicates were able to activate T cells. The activity was lost after long-term culture of H. pylori on agar-plates. Degradation of H. pylori proteins with specific peptidases dramatically reduced the stimulating ability, implicating that the responsible molecule is likely to be a protein. This unexpected polyclonal T cell stimulatory mechanism may contribute to the T cell-mediated pathogenicity characteristic for H. pylori-mediated diseases.
authors.affiliation: Institut für Medizinische Mikrobiologie und Hygiene der Universität Marburg, Marburg, Germany. rosenpla@med.uni-marburg.de
authors.forename: Christine
authors.initials: C
authors.lastname: Rosenplänter
authors.forename: Frank
authors.initials: F
authors.lastname: Sommer
authors.forename: Peter
authors.initials: P
authors.lastname: Kleemann
authors.forename: Anna
authors.initials: A
authors.lastname: Belkovets
authors.forename: Annette
authors.initials: A
authors.lastname: Schmidt
authors.forename: Michael
authors.initials: M
authors.lastname: Lohoff
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000821:virology*; D002450:Cell Communication / Q000276:immunology; D018920:Coculture Techniques; D005260:Female; D016481:Helicobacter Infections / Q000276:immunology; D016480:Helicobacter pylori / Q000276:immunology*; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology*; D051379:Mice