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CpG-matured murine plasmacytoid dendritic cells are capable of in vivo priming of functional CD8 T cell responses to endogenous but not exogenous antigens.

Salio M, Palmowski MJ, Atzberger A, Hermans IF, Cerundolo V - J. Exp. Med. (2004)

Bottom Line: In vitro experiments have shown that upon maturation, human and murine PDCs develop into potent immunostimulatory cells; however, their ability to prime an immune response in vivo remains to be addressed.In contrast, immature PDCs are unable to prime antigen-specific CTLs.Our results underline the heterogeneity and plasticity of different antigen-presenting cells, and reveal an important role of mature PDCs in priming CD8 responses to endogenous antigens, in addition to their previously reported ability to modulate antiviral responses via type I IFN.

View Article: PubMed Central - PubMed

Affiliation: Cancer Research Tumor Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Headley Way, OX3 9DS Oxford, UK. mariolina.salio@imm.ox.ac.uk

ABSTRACT
Plasmacytoid dendritic cells (PDCs) are a unique leukocyte population capable of secreting high levels of type I interferon (IFN) in response to viruses and bacterial stimuli. In vitro experiments have shown that upon maturation, human and murine PDCs develop into potent immunostimulatory cells; however, their ability to prime an immune response in vivo remains to be addressed. We report that CpG-matured murine PDCs are capable of eliciting in naive mice antigen-specific CTLs against endogenous antigens as well as exogenous peptides, but not against an exogenous antigen. Type I IFN is not required for priming, as injection of CpG-matured PDCs into type I IFN receptor-deficient mice elicits functional CTL responses. Mature PDCs prime CTLs that secrete IFN-gamma and protect mice from a tumor challenge. In contrast, immature PDCs are unable to prime antigen-specific CTLs. However, mice injected with immature PDCs are fully responsive to secondary antigenic challenges, suggesting that PDCs have not induced long-lasting tolerance via anergic or regulatory T cells. Our results underline the heterogeneity and plasticity of different antigen-presenting cells, and reveal an important role of mature PDCs in priming CD8 responses to endogenous antigens, in addition to their previously reported ability to modulate antiviral responses via type I IFN.

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Intravenous injection of CpG-matured male PDCs induces type I polarization of spleen CTL. C57BL/6 mice (n = 3) were injected i.v. with 105 male CpG-matured MDC or PDCs. Splenocytes from a mouse primed by CpG-matured PDCs were in vitro restimulated with UTY246–254 peptide or PMA and ionomycin, and intracellular cytokine accumulation was assessed as described in Materials and Methods 8 d after priming. The tetramer staining for the same sample is also shown. One experiment representative of three is shown. Similar profiles were obtained in mice primed by CpG-matured male MDC, whereas naive female C57BL/6 controls did not respond to the peptide.
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fig4: Intravenous injection of CpG-matured male PDCs induces type I polarization of spleen CTL. C57BL/6 mice (n = 3) were injected i.v. with 105 male CpG-matured MDC or PDCs. Splenocytes from a mouse primed by CpG-matured PDCs were in vitro restimulated with UTY246–254 peptide or PMA and ionomycin, and intracellular cytokine accumulation was assessed as described in Materials and Methods 8 d after priming. The tetramer staining for the same sample is also shown. One experiment representative of three is shown. Similar profiles were obtained in mice primed by CpG-matured male MDC, whereas naive female C57BL/6 controls did not respond to the peptide.

Mentions: To further characterize the type of polarization induced by priming with mature PDCs, freshly isolated splenocytes were stimulated in vitro with the UTY246–254 peptide or PMA + ionomycin 8 d after priming. Analysis of intracellular cytokines revealed that CD8 T cells secreted the type 1 cytokine IFN-γ in response to both the specific peptide and PMA + ionomycin (Fig. 4). IL-2 was also detected in CD8 T cells stimulated with PMA + ionomycin. In contrast, CD8 cells did not secrete the type 2 cytokines IL-4 and IL-10 in response to either stimulation protocol. IL-4 and IL-10 were secreted only by the CD8 negative cells in response to PMA + ionomycin. A similar pattern of polarization was observed in mice primed by mature MDCs (unpublished data). Although the frequencies of tetramer+ cells in the spleen and in the blood were comparable, a higher proportion of splenic UTY246–254-specific CTLs secreted IFN-γ in response to the specific peptide (Fig. 4; not depicted), which may reflect homing of effector T cells to the spleen. We conclude that mature PDCs are able to efficiently prime antigen-specific CTLs, capable of cytolytic activity and IFN-γ secretion.


CpG-matured murine plasmacytoid dendritic cells are capable of in vivo priming of functional CD8 T cell responses to endogenous but not exogenous antigens.

Salio M, Palmowski MJ, Atzberger A, Hermans IF, Cerundolo V - J. Exp. Med. (2004)

Intravenous injection of CpG-matured male PDCs induces type I polarization of spleen CTL. C57BL/6 mice (n = 3) were injected i.v. with 105 male CpG-matured MDC or PDCs. Splenocytes from a mouse primed by CpG-matured PDCs were in vitro restimulated with UTY246–254 peptide or PMA and ionomycin, and intracellular cytokine accumulation was assessed as described in Materials and Methods 8 d after priming. The tetramer staining for the same sample is also shown. One experiment representative of three is shown. Similar profiles were obtained in mice primed by CpG-matured male MDC, whereas naive female C57BL/6 controls did not respond to the peptide.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2211835&req=5

fig4: Intravenous injection of CpG-matured male PDCs induces type I polarization of spleen CTL. C57BL/6 mice (n = 3) were injected i.v. with 105 male CpG-matured MDC or PDCs. Splenocytes from a mouse primed by CpG-matured PDCs were in vitro restimulated with UTY246–254 peptide or PMA and ionomycin, and intracellular cytokine accumulation was assessed as described in Materials and Methods 8 d after priming. The tetramer staining for the same sample is also shown. One experiment representative of three is shown. Similar profiles were obtained in mice primed by CpG-matured male MDC, whereas naive female C57BL/6 controls did not respond to the peptide.
Mentions: To further characterize the type of polarization induced by priming with mature PDCs, freshly isolated splenocytes were stimulated in vitro with the UTY246–254 peptide or PMA + ionomycin 8 d after priming. Analysis of intracellular cytokines revealed that CD8 T cells secreted the type 1 cytokine IFN-γ in response to both the specific peptide and PMA + ionomycin (Fig. 4). IL-2 was also detected in CD8 T cells stimulated with PMA + ionomycin. In contrast, CD8 cells did not secrete the type 2 cytokines IL-4 and IL-10 in response to either stimulation protocol. IL-4 and IL-10 were secreted only by the CD8 negative cells in response to PMA + ionomycin. A similar pattern of polarization was observed in mice primed by mature MDCs (unpublished data). Although the frequencies of tetramer+ cells in the spleen and in the blood were comparable, a higher proportion of splenic UTY246–254-specific CTLs secreted IFN-γ in response to the specific peptide (Fig. 4; not depicted), which may reflect homing of effector T cells to the spleen. We conclude that mature PDCs are able to efficiently prime antigen-specific CTLs, capable of cytolytic activity and IFN-γ secretion.

Bottom Line: In vitro experiments have shown that upon maturation, human and murine PDCs develop into potent immunostimulatory cells; however, their ability to prime an immune response in vivo remains to be addressed.In contrast, immature PDCs are unable to prime antigen-specific CTLs.Our results underline the heterogeneity and plasticity of different antigen-presenting cells, and reveal an important role of mature PDCs in priming CD8 responses to endogenous antigens, in addition to their previously reported ability to modulate antiviral responses via type I IFN.

View Article: PubMed Central - PubMed

Affiliation: Cancer Research Tumor Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Headley Way, OX3 9DS Oxford, UK. mariolina.salio@imm.ox.ac.uk

ABSTRACT
Plasmacytoid dendritic cells (PDCs) are a unique leukocyte population capable of secreting high levels of type I interferon (IFN) in response to viruses and bacterial stimuli. In vitro experiments have shown that upon maturation, human and murine PDCs develop into potent immunostimulatory cells; however, their ability to prime an immune response in vivo remains to be addressed. We report that CpG-matured murine PDCs are capable of eliciting in naive mice antigen-specific CTLs against endogenous antigens as well as exogenous peptides, but not against an exogenous antigen. Type I IFN is not required for priming, as injection of CpG-matured PDCs into type I IFN receptor-deficient mice elicits functional CTL responses. Mature PDCs prime CTLs that secrete IFN-gamma and protect mice from a tumor challenge. In contrast, immature PDCs are unable to prime antigen-specific CTLs. However, mice injected with immature PDCs are fully responsive to secondary antigenic challenges, suggesting that PDCs have not induced long-lasting tolerance via anergic or regulatory T cells. Our results underline the heterogeneity and plasticity of different antigen-presenting cells, and reveal an important role of mature PDCs in priming CD8 responses to endogenous antigens, in addition to their previously reported ability to modulate antiviral responses via type I IFN.

Show MeSH
Related in: MedlinePlus