Limits...
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.

Show MeSH

Related in: MedlinePlus

Intravenous injection of CpG-matured male PDCs induces functional CTL responses. C57BL/6 mice (n = 5) were primed as described in Fig. 1 A. (A) CTL responses were assessed in the blood by ex vivo FACS® analysis using UTY246–254-H-2-Db tetramers 7 d after priming. One representative animal per group is shown. (B) 10 d after priming, cytolytic activity of the UTY246–254-specific cells was assessed in vivo against female syngeneic splenocytes unpulsed or peptide pulsed (CFSE labeled), male splenocytes unpulsed (CFSE labeled), or peptide pulsed (5-(and 6)-([{4-chloromethyl}benzoyl]amino) tetramethylrhodamine labeled) as summarized in the cartoon. Correlation between tetramer staining (A) and lysis of CFSE-labeled target cells at 17 and 96 h (B) is shown. The mouse primed by CpG-PDCs has a total of 2% UTY246–254-CTL (as a percentage of CD8 cells). (C) Analysis of mean antigen-specific lysis 17 h after target cell injection, calculated as described in Materials and Methods. Cells used for priming are shown on the x axis. Each panel depicts specific lysis of the labeled targets (top left).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2211835&req=5

fig2: Intravenous injection of CpG-matured male PDCs induces functional CTL responses. C57BL/6 mice (n = 5) were primed as described in Fig. 1 A. (A) CTL responses were assessed in the blood by ex vivo FACS® analysis using UTY246–254-H-2-Db tetramers 7 d after priming. One representative animal per group is shown. (B) 10 d after priming, cytolytic activity of the UTY246–254-specific cells was assessed in vivo against female syngeneic splenocytes unpulsed or peptide pulsed (CFSE labeled), male splenocytes unpulsed (CFSE labeled), or peptide pulsed (5-(and 6)-([{4-chloromethyl}benzoyl]amino) tetramethylrhodamine labeled) as summarized in the cartoon. Correlation between tetramer staining (A) and lysis of CFSE-labeled target cells at 17 and 96 h (B) is shown. The mouse primed by CpG-PDCs has a total of 2% UTY246–254-CTL (as a percentage of CD8 cells). (C) Analysis of mean antigen-specific lysis 17 h after target cell injection, calculated as described in Materials and Methods. Cells used for priming are shown on the x axis. Each panel depicts specific lysis of the labeled targets (top left).

Mentions: The functional state of the induced UTY246–254-specific CTLs was investigated by assessing their cytotoxic capacity and cytokine secretion upon antigen exposure. Cytotoxicity was assayed in vivo against syngeneic splenocyte targets, either male or peptide-pulsed female that had been labeled with a fluorescent dye and injected into the lateral vein 10 d after priming. Specific lysis of the antigen-expressing cells was determined against control female splenocytes not pulsed with the UTY246–254 peptide. UTY246–254-specific CTLs primed by mature PDCs efficiently lysed pulsed with 10 μg/ml of peptide female cells, as well as unpulsed male splenocytes (Fig. 2, B and C). Lysis of unpulsed male splenocytes, expressing a much lower density of UTY246–254–Db complexes than UTY246–254 peptide-pulsed cells, is indicative of expansion of high affinity CTLs. The majority of peptide-pulsed female targets were lysed within the first 17 h, whereas lysis of unpulsed male cells continued over the next 96 h, consistent with UTY246–254–Db complexes being presented at lower density but continuously over time (Fig. 2 B; not depicted). The cytolytic activity detected in mice primed by immature and mature MDCs correlated with the extent of CTL priming. No specific lysis above background was observed in mice primed by immature PDCs, mirroring the lack of detectable CTLs in the blood.


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 functional CTL responses. C57BL/6 mice (n = 5) were primed as described in Fig. 1 A. (A) CTL responses were assessed in the blood by ex vivo FACS® analysis using UTY246–254-H-2-Db tetramers 7 d after priming. One representative animal per group is shown. (B) 10 d after priming, cytolytic activity of the UTY246–254-specific cells was assessed in vivo against female syngeneic splenocytes unpulsed or peptide pulsed (CFSE labeled), male splenocytes unpulsed (CFSE labeled), or peptide pulsed (5-(and 6)-([{4-chloromethyl}benzoyl]amino) tetramethylrhodamine labeled) as summarized in the cartoon. Correlation between tetramer staining (A) and lysis of CFSE-labeled target cells at 17 and 96 h (B) is shown. The mouse primed by CpG-PDCs has a total of 2% UTY246–254-CTL (as a percentage of CD8 cells). (C) Analysis of mean antigen-specific lysis 17 h after target cell injection, calculated as described in Materials and Methods. Cells used for priming are shown on the x axis. Each panel depicts specific lysis of the labeled targets (top left).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2211835&req=5

fig2: Intravenous injection of CpG-matured male PDCs induces functional CTL responses. C57BL/6 mice (n = 5) were primed as described in Fig. 1 A. (A) CTL responses were assessed in the blood by ex vivo FACS® analysis using UTY246–254-H-2-Db tetramers 7 d after priming. One representative animal per group is shown. (B) 10 d after priming, cytolytic activity of the UTY246–254-specific cells was assessed in vivo against female syngeneic splenocytes unpulsed or peptide pulsed (CFSE labeled), male splenocytes unpulsed (CFSE labeled), or peptide pulsed (5-(and 6)-([{4-chloromethyl}benzoyl]amino) tetramethylrhodamine labeled) as summarized in the cartoon. Correlation between tetramer staining (A) and lysis of CFSE-labeled target cells at 17 and 96 h (B) is shown. The mouse primed by CpG-PDCs has a total of 2% UTY246–254-CTL (as a percentage of CD8 cells). (C) Analysis of mean antigen-specific lysis 17 h after target cell injection, calculated as described in Materials and Methods. Cells used for priming are shown on the x axis. Each panel depicts specific lysis of the labeled targets (top left).
Mentions: The functional state of the induced UTY246–254-specific CTLs was investigated by assessing their cytotoxic capacity and cytokine secretion upon antigen exposure. Cytotoxicity was assayed in vivo against syngeneic splenocyte targets, either male or peptide-pulsed female that had been labeled with a fluorescent dye and injected into the lateral vein 10 d after priming. Specific lysis of the antigen-expressing cells was determined against control female splenocytes not pulsed with the UTY246–254 peptide. UTY246–254-specific CTLs primed by mature PDCs efficiently lysed pulsed with 10 μg/ml of peptide female cells, as well as unpulsed male splenocytes (Fig. 2, B and C). Lysis of unpulsed male splenocytes, expressing a much lower density of UTY246–254–Db complexes than UTY246–254 peptide-pulsed cells, is indicative of expansion of high affinity CTLs. The majority of peptide-pulsed female targets were lysed within the first 17 h, whereas lysis of unpulsed male cells continued over the next 96 h, consistent with UTY246–254–Db complexes being presented at lower density but continuously over time (Fig. 2 B; not depicted). The cytolytic activity detected in mice primed by immature and mature MDCs correlated with the extent of CTL priming. No specific lysis above background was observed in mice primed by immature PDCs, mirroring the lack of detectable CTLs in the blood.

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