title: 'Ignorance' of antigen-specific murine CD4+ and CD8+ T cells is overruled by lipopolysaccharide and leads to specific induction of IFN-gamma.
abstract: Lipopolysaccharide (LPS) can activate human and murine T cells in vivo and in vitro. Here we analysed the effects of LPS on T cells with defined specificities in T-cell receptor (TCR)-transgenic systems. LPS rapidly induced high amounts of interferon (IFN)-gamma in a subpopulation of purified T cells from DO11.10 (OVA323-339/H2-Ad) and OT-1 (OVA257-264/H2-Kb) mice when coincubated with antigen-pulsed peritoneal exudate cells (PECs). LPS induced IFN-gamma in T cell cultures even when the number of antigenic major histocompatibility complex (MHC) class-I complexes was too small to stimulate the T cells. LPS, thus, overruled the unresponsiveness of the otherwise 'antigen-ignorant' T cells. The release of IFN-gamma strictly correlates with the PECs' ability to produce interleukin (IL)-12. In contrast to the induction of IFN-gamma, antigen-specific IL-2 secretion and proliferation of T cells were rather decreased in the presence of LPS. Only very few IFN-gamma-secreting natural killer (NK) cells and natural killer T (NKT) cells in the given experimental system could be detected using intracellular fluorescence-activated cell sorter (FACS) staining. Taken together, our results indicate that LPS has the potential to activate quiescent T cells and to specifically induce IFN-gamma in CD4 and CD8 T cells. This may have direct consequences for the activation of autoreactive T cells following bacterial infections.
authors.affiliation: Bernhard-Nocht-Institute for Tropical Medicine, Bernhard-Nochtstr, Hamburg, Germany.
authors.forename: S H
authors.initials: SH
authors.lastname: Moré
authors.forename: M
authors.initials: M
authors.lastname: Breloer
authors.forename: A K
authors.initials: AK
authors.lastname: Fentz
authors.forename: B
authors.initials: B
authors.lastname: Fleischer
authors.forename: A
authors.initials: A
authors.lastname: von Bonin
mesh_terms: D000818:Animals; D000941:Antigens / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D007371:Interferon-gamma / Q000096:biosynthesis*; D018664:Interleukin-12 / Q000502:physiology; D018950:Lipopolysaccharide Receptors / Q000502:physiology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects*; D051379:Mice; D011948:Receptors, Antigen, T-Cell / Q000502:physiology
chemical_list: D000941:Antigens; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D011948:Receptors, Antigen, T-Cell; D018664:Interleukin-12; D007371:Interferon-gamma