Dendritic cells matured by inflammation induce CD86-dependent priming of naive CD8+ T cells in the absence of their cognate peptide antigen.
Dendritic cells (DC) licensed by the interaction between pathogen products and pattern recognition receptors can activate naive T cells to undergo Ag-dependent proliferation and cytokine production. In contrast, DC induced to mature by trans-acting inflammatory stimuli are believed to only be capable of supporting Ag-dependent proliferative responses. In this study, we show that uninfected DC matured as a consequence of Leishmania-induced inflammation induce CD8(+) T cells to proliferate in the absence of their cognate Ag. We separated splenic DC from Leishmania donovani-infected mice into those that contained parasites and had been activated to induce IL-12p40, from those that had undergone only partial maturation, measured by increased CD86 expression in the absence of IL-12p40 induction. We then showed that these partially matured DC could induce exogenous peptide-independent proliferation of OT-I and F5 CD8(+) TCR transgenic T cells, as well as polyclonal CD8(+) T cells. Proliferation of OT-I cells was significantly inhibited in vitro and in vivo by anti-CD86 mAb but not by anti-CD80 mAb and could also be inhibited by cyclosporine A. Proliferating OT-I cells did not produce IFN-gamma, even when re-exposed to mature DC. However, these primed OT-I cells subsequently produced effector cytokines, not just on exposure to their cognate peptide but, more importantly, to weak exogenous TCR agonists that otherwise failed to induce IFN-gamma. We further showed that OT-I cells undergoing locally driven proliferation to another pathogen, Streptococcus pneumoniae, rapidly seeded other lymphoid tissues, suggesting that CD8(+) T cells primed in this way may play a role in rapidly countering pathogen dissemination.
Maroof
Asher
A
Centre for Immunology and Infection, Hull York Medical School and Department of Biology, University of York, Wentworth Way, York, United Kingdom.
Beattie
Lynette
L
Kirby
Alun
A
Coles
Mark
M
Kaye
Paul M
PM
D019264:Adoptive Transfer; D000818:Animals; D000953:Antigens, Protozoan / Q000276:immunology; D051940:B7-2 Antigen / Q000276:immunology*; D024201:Bystander Effect / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002454:Cell Differentiation / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology*; D005434:Flow Cytometry; D007249:Inflammation / Q000276:immunology*; D007893:Leishmania donovani / Q000276:immunology; D007898:Leishmaniasis, Visceral / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000953:Antigens, Protozoan; D051940:B7-2 Antigen