scholarly journals Skin dendritic cells in melanoma are key for successful checkpoint blockade therapy

2021 ◽  
Vol 9 (1) ◽  
pp. e000832
Author(s):  
Anastasia Prokopi ◽  
Christoph H Tripp ◽  
Bart Tummers ◽  
Florian Hornsteiner ◽  
Sarah Spoeck ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Tumor Growth ◽  
Tumor Progression ◽  
Cd8 T Cells ◽  
Checkpoint Blockade ◽  
Tumor Stages ◽  
Tumor Immunogenicity

BackgroundImmunotherapy with checkpoint inhibitors has shown impressive results in patients with melanoma, but still many do not benefit from this line of treatment. A lack of tumor-infiltrating T cells is a common reason for therapy failure but also a loss of intratumoral dendritic cells (DCs) has been described.MethodsWe used the transgenic tg(Grm1)EPv melanoma mouse strain that develops spontaneous, slow-growing tumors to perform immunological analysis during tumor progression. With flow cytometry, the frequencies of DCs and T cells at different tumor stages and the expression of the inhibitory molecules programmed cell death protein-1 (PD-1) and T-cell immunoglobulin and mucin-domain containing-3 (TIM-3) on T cells were analyzed. This was complemented with RNA-sequencing (RNA-seq) and real-time quantitative PCR (RT-qPCR) analysis to investigate the immune status of the tumors. To boost DC numbers and function, we administered Fms-related tyrosine 3 ligand (Flt3L) plus an adjuvant mix of polyI:C and anti-CD40. To enhance T cell function, we tested several checkpoint blockade antibodies. Immunological alterations were characterized in tumor and tumor-draining lymph nodes (LNs) by flow cytometry, CyTOF, microarray and RT-qPCR to understand how immune cells can control tumor growth. The specific role of migratory skin DCs was investigated by coculture of sorted DC subsets with melanoma-specific CD8+ T cells.ResultsOur study revealed that tumor progression is characterized by upregulation of checkpoint molecules and a gradual loss of the dermal conventional DC (cDC) 2 subset. Monotherapy with checkpoint blockade could not restore antitumor immunity, whereas boosting DC numbers and activation increased tumor immunogenicity. This was reflected by higher numbers of activated cDC1 and cDC2 as well as CD4+ and CD8+ T cells in treated tumors. At the same time, the DC boost approach reinforced migratory dermal DC subsets to prime gp100-specific CD8+ T cells in tumor-draining LNs that expressed PD-1/TIM-3 and produced interferon γ (IFNγ)/tumor necrosis factor α (TNFα). As a consequence, the combination of the DC boost with antibodies against PD-1 and TIM-3 released the brake from T cells, leading to improved function within the tumors and delayed tumor growth.ConclusionsOur results set forth the importance of skin DC in cancer immunotherapy, and demonstrates that restoring DC function is key to enhancing tumor immunogenicity and subsequently responsiveness to checkpoint blockade therapy.

scholarly journals Pre-existing intratumoral CD8 T cells substantially contribute to control tumors following therapeutic anti-CD40 and polyI:C based vaccination

2020 ◽  
Author(s):  
Aaron D. Stevens ◽  
Timothy N.J. Bullock
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Tumor Growth ◽  
Cd8 T Cells ◽  
Tumor Control ◽  
Cell Trafficking ◽  
T Cell Trafficking ◽  
Cell Numbers

ABSTRACTBackgroundDendritic cells are potently activated by the synergistic action of CD40 stimulation in conjunction with signaling through toll like receptors, subsequently activating antigen specific T cells. Cancer vaccines targeting the activation of dendritic cells in this manner show promise in murine models and are being developed for human cancer patients. While vaccine efficacy has been established, further investigation is needed to understand the mechanism of tumor control and how vaccination alters tumor infiltrating immune cells.MethodsMice bearing established murine melanoma tumors were vaccinated with agonist anti-CD40, polyI:C, and tumor antigen. Intratumoral T cell numbers, differentiation state, proliferation, and survival were assessed by flow cytometry. T cell effector function was measured both within the tumor and ex vivo by flow cytometry. T cell trafficking was blocked to examine changes to intratumoral T cells present at the time of vaccination.ResultsVaccination led to increased intratumoral T cell numbers and delayed tumor growth. Expansion of T cells and tumor control did not require trafficking of T cells from the periphery. The increase in intratumoral T cells was associated with an acute burst in proliferation but not changes in viability. Intratumoral T cells had lower PD-1 and Eomes expression but were less functional after vaccination on a per cell basis. However, the increased intratumoral T cell numbers yielded increased effector T cells per tumor.ConclusionsPre-infiltrated CD8 T cells are responsive to CD40/TLR-mediated vaccination and sufficient for vaccination to delay tumor growth when additional T cell trafficking is blocked. This indicates that the existing T cell response and intratumoral DC could be critical for vaccination efficacy. This also suggests that circulating T cells may not be an appropriate biomarker for vaccination efficacy.

C5a Complement Depletion Suppresses In Vivo B Lymphoma Progression and Enhances Development Of Cellular Anti-Tumor Immune Response

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1837-1837
Author(s):  
Suresh Veeramani ◽  
George J. Weiner
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Tumor Growth ◽  
Tumor Progression ◽  
Cd8 T Cells ◽  
B Lymphoma

Abstract Background Proteins within the complement system have complex effects on cellular immune responses. In previous studies, we found that active complement components, especially C5a, can dampen the development of antigen-specific immune responses following vaccination with a model antigen, in part by promoting generation of APC-induced T regulatory (Treg) cells. These studies also demonstrated that B lymphoma cell lines exposed to complement can induce Treg generation in vitro. The current study was designed to address whether depletion of C5a could enhance development of a cellular anti-lymphoma immune response in vivo. Methods Immunocompetent Balb/C mice were inoculated subcutaneously with syngeneic A20 B lymphoma cells mixed with either 10 μg of rat anti-mouse C5a monoclonal antibody (mAb) or 10 μg of isotype-matched Rat IgG2a control mAb. Tumor growth was followed. In select experiments, mice were sacrificed and analyzed for the percentage and activity of tumor-infiltrating T cells and A20-specific splenic T cell responses. Results 1. Tumor progression. Lymphoma grew more slowly in mice treated with anti-C5a mAb compared to mice treated with control mAb (p<0.05) {Fig. 1). 2. Intratumoral T cells. Tumors from mice treated with anti-C5a mAb had higher CD8+ T cell infiltration compared to mice treated with control mAb (p=0.002) (Fig. 2). Tumor-infiltrating CD8+ T cells showed a trend towards higher intracellular IFNg production in mice treated with anti-C5a mAb compared to control mAb (p=0.051). 3. Splenic T cells. Splenic T cells from mice treated with anti-C5a mAb produced IFNg to a greater degree than did splenic T cells from control mice when splenocytes were cultured with irradiated A20 cells in vitro (p=0.041) (Fig. 3). There was a trend towards decreased numbers of splenic CD4+CD25highFoxp3+ Tregs in C5a-depleted mice compared to control mice. Conclusions Depletion of C5a at the site of tumor inoculation slows tumor growth and increases the number of tumor infiltrating CD8 T cells in a syngenic immunocompetent model of lymphoma. A trend towards enhanced production of IFNg in the tumor infiltrating T cells, increased numbers of tumor-specific splenic T cells, and reduced numbers of splenic Tregs, suggests intratumoral C5a depletion can enhance tumor-specific immune responses both within the tumor and systemically. Ongoing studies are exploring the molecular mechanisms involved in C5a-promoted tumor progression and the use of C5a depletion as a novel strategy to improve anti-tumor immunity. Disclosures: No relevant conflicts of interest to declare.

scholarly journals P03.31 Skin dendritic cells in melanoma are key for successful checkpoint blockade therapy

2020 ◽  
Vol 8 (Suppl 2) ◽  
pp. A35.2-A36
Author(s):  
N Prokopi ◽  
CH Tripp ◽  
B Tummers ◽  
JC Crawford ◽  
M Efremova ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
Tumor Microenvironment ◽  
Mouse Model ◽  
Tumor Growth ◽  
Tumor Immunity ◽  
Cd8 T Cells ◽  
Checkpoint Blockade ◽  
And Function

BackgroundImmunotherapy of cancer by checkpoint blockade has significantly improved the survival of melanoma patients. However, in patients with tumors that are poorly infiltrated by effector T cells the clinical results are not encouraging. Therefore, combination approaches that enhance pre-existing anti-tumor immunity and reset the patients‘ immunological status are urgently needed. In this study we used the tg(Grm1)EPv melanoma mouse model that reflects a non-immunogenic tumor microenvironment. In this mouse model, spontaneous melanoma development is driven by the ectopic expression of the metabotropic glutamate receptor-1 in melanocytes, which confers to them a hyperproliferative and anti-apoptotic phenotype. The same alteration has been shown to be present in 40% of melanoma patient samples. The aim of our study was to investigate whether enhancing dendritic cell (DC) numbers and function in the tg(Grm1)EPv mouse model could restore responsiveness to checkpoint blockade.Material and MethodsWe used multicolor flow cytometry, gene expression analysis by RNA-seq and microarray to analyze tumors and tumor-draining lymph nodes (tdLN). With various immunological in vitro and in vivo assays we determined the functional role of DC in tumor immunity.ResultsA loss of skin DC has previously been reported for primary melanoma lesions and we here show that melanoma progression in the tg(Grm1)EPv mouse model coincides with a gradual decrease in the skin cDC2 subset and an upregulation of the inhibitory ligands PD-L1 and galectin-9. Monotherapy with anti-PD-L1 could not delay tumor growth, suggesting that this is a good model to study resistance to checkpoint blockade. We hypothesized that by boosting DC numbers and function we would restore responsiveness to checkpoint blockade. By administering a treatment consisting of systemic Flt3L and intratumoral polyI:C/anti-CD40, we were able to rescue the numbers and function of skin cDC2. Analysis of the treated tumors by flow cytometry showed that the DC boost regimen led to an increased tumor infiltration of activated CD4+ and CD8+T cells. An in vitro T cell proliferation assay revealed that dermal cDC2 that had migrated to the tdLN, played a crucial role in this process, since these were able to cross-present endogenous gp100 antigen more efficiently than migratory Langerhans cells and dermal cDC1. CD4+ and CD8+T cells recruited in the tumors of the DC boost treated mice, expressed PD-1 and TIM-3. Therefore, combination therapy with checkpoint blockade of these molecules resulted in increased cytotoxic activity within the tumor and eventually delay of tumor growth.ConclusionsOur results demonstrate that skin DC shape the tumor microenvironment upon immunotherapy and thus, therapies that aim to enhance responsiveness to checkpoint blockade may well benefit from a component that boosts the numbers and the function of skin DC.Disclosure InformationN. Prokopi: None. C.H. Tripp: None. B. Tummers: None. J.C. Crawford: None. M. Efremova: None. K. Hutter: None. L. Bellmann: None. G. Cappellano: None. L. Boon: None. D. Ortner: None. Z. Trajanoski: None. S. Chen: None. T. de Gruijl: None. D.R. Green: None. P. Stoitzner: None.

scholarly journals 275 Flow cytometry and nanoString provide a comprehensive cell- and gene-based tumor profile following checkpoint inhibition in a murine bladder cancer model

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A298-A298
Author(s):  
David Draper ◽  
Philip Lapinski ◽  
Scott Wise
Keyword(s):  
Flow Cytometry ◽  
Bladder Cancer ◽  
T Cells ◽  
T Cell ◽  
Tumor Growth ◽  
Cd8 T Cells ◽  
Combination Treatment ◽  
Immune Gene ◽  
Cell Recruitment ◽  
Anti Tumor Activity

BackgroundBladder cancer (BC) is the thirteenth leading cause of cancer-related deaths.1 Five checkpoint immunotherapies that target the PD-1/PD-L1 axis are FDA approved, and gene- and protein-based approaches are helping to identify new combination treatment strategies for therapeutic intervention.2 Using the murine MB49 model for BC, we demonstrate how non-targeted immune gene expression profiling can combine with flow cytometry to provide a gene and cell-specific signature for the tumor microenvironment and help identify potential targets for novel treatment approaches.MethodsAnimals with established MB49 tumors were treated with anti-mPD-1 or isotype control antibodies. Tumors were collected 7 days after the last treatment. Flow cytometry examined anti-mPD-1 treatment-induced immunophenotypic modulation for eleven tumor-infiltrating immune subsets. The mouse PanCancer IO 360™ panel (NanoString) provided transcriptomic analysis of 770 immuno-oncology-related genes. The ROSALIND™ platform (OnRamp BioInformatics) was used to identify differentially regulated genes between treatment groups (±1.5 fold-change; p <0.05).ResultsAnti-mPD-1 had moderate anti-tumor activity, with a 58% tumor growth inhibition at day 18 post-implant in treated compared to control animals. Flow cytometry revealed anti-mPD-1 triggered an increase in tumor-infiltrating CD8+ T cells (45%) compared to control animals. Furthermore, the CD8+ T cell phenotype was altered by anti-mPD-1 treatment. The percentage of CD8+ T cells that expressed ICOS and LAG-3 was increased in tumors from anti-mPD-1 treated animals (22% and 35% respectively). A reduction in PD-1 expression was also observed (33%). In myeloid cells, iNOS expression increased in tumor-associated macrophages from treated animals compared to controls. NanoString analysis revealed 62 genes were differentially regulated in tumors from anti-mPD-1 treated animals compared to controls. ROSALIND analysis classified 30 of the genes as regulators of interferon, cytotoxicity, antigen presentation, and cytokine/chemokine signaling. Also, among the genes upregulated by anti-mPD-1 were IDO, HAVCR2 (TIM-3), and CSFR1, which can promote tumor growth and are clinical targets actively being investigated for new immunotherapies.ConclusionsNanoString analysis complemented flow cytometry to provide a comprehensive profile of the MB49 tumor. Together, these data demonstrate that anti-mPD1 increases T cell recruitment into the tumor and upregulates the expression of genes known to enhance T cell recruitment and anti-tumor activity. iNOS protein upregulation indicates that anti-mPD-1 treatment may also exert effects by reprogramming M2 macrophages towards an M1 phenotype. Upregulation of IDO, HAVCR2, and CSFR1 genes may effectively counteract anti-mPD-1 treatment. Further investigation may elucidate clinical implications for inhibitors of these gene products as combination treatment partners with anti-mPD-1.ReferencesSaginala K, Barsouk A, Aluru JS, Rawla P, Padala SA, Barsouk A. Epidemiology of bladder cancer. Med Sci 2020;1:15–26. Lopez-Beltran A, Cimadamore A, Blanca A, Massari F, Vau N, Scarpelli M, Cheng L, Montironi R. Immune checkpoint inhibitors for the treatment of bladder cancer. Cancers 2021;1:131–146.Ethics ApprovalN/A

scholarly journals Checkpoint blockade accelerates a novel switch from an NKT-driven TNFα response toward a T cell driven IFN-γ response within the tumor microenvironment

2021 ◽  
Vol 9 (6) ◽  
pp. e002269
Author(s):  
Shota Aoyama ◽  
Ryosuke Nakagawa ◽  
Satoshi Nemoto ◽  
Patricio Perez-Villarroel ◽  
James J Mulé ◽  
...  
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Cell ◽  
Tumor Growth ◽  
Ex Vivo ◽  
T Cell Response ◽  
Effector Function ◽  
Checkpoint Blockade ◽  
Necrosis Factor Alpha ◽  
Ifn Γ

BackgroundThe temporal response to checkpoint blockade (CB) is incompletely understood. Here, we profiled the tumor infiltrating lymphocyte (TIL) landscape in response to combination checkpoint blockade at two distinct timepoints of solid tumor growth.MethodsC57BL/6 mice bearing subcutaneous MC38 tumors were treated with anti-PD-1 and/or anti-CTLA-4 antibodies. At 11 or 21 days, TIL phenotype and effector function were analyzed in excised tumor digests using high parameter flow cytometry. The contributions of major TIL populations toward overall response were then assessed using ex vivo cytotoxicity and in vivo tumor growth assays.ResultsThe distribution and effector function among 37 distinct TIL populations shifted dramatically between early and late MC38 growth. At 11 days, the immune response was dominated by Tumor necrosis factor alpha (TNFα)-producing NKT, representing over half of all TIL. These were accompanied by modest frequencies of natural killer (NK), CD4+, or CD8+ T cells, producing low levels of IFN-γ. At 21 days, NKT populations were reduced to a combined 20% of TIL, giving way to increased NK, CD4+, and CD8+ T cells, with increased IFN-γ production. Treatment with CB accelerated this switch. At day 11, CB reduced NKT to less than 20% of all TIL, downregulated TNFα across NKT and CD4+ T cell populations, increased CD4+ and CD8+ TIL frequencies, and significantly upregulated IFN-γ production. Degranulation was largely associated with NK and NKT TIL. Blockade of H-2kb and/or CD1d during ex vivo cytotoxicity assays revealed NKT has limited direct cytotoxicity against parent MC38. However, forced CD1d overexpression in MC38 cells significantly diminished tumor growth, suggesting NKT TIL exerts indirect control over MC38 growth.ConclusionsDespite an indirect benefit of early NKT activity, CB accelerates a switch from TNFα, NKT-driven immune response toward an IFN-γ driven CD4+/CD8+ T cell response in MC38 tumors. These results uncover a novel NKT/T cell switch that may be a key feature of CB response in CD1d+ tumors.

scholarly journals Characterization of human cytomegalovirus peptide–specific CD8+ T-cell repertoire diversity following in vitro restimulation by antigen-pulsed dendritic cells

Blood ◽  
2002 ◽  
Vol 99 (1) ◽  
pp. 213-223 ◽  
Author(s):  
Karl Peggs ◽  
Stephanie Verfuerth ◽  
Arnold Pizzey ◽  
Jenni Ainsworth ◽  
Paul Moss ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Viral Replication ◽  
Cd8 T Cells ◽  
Cd8 T Cell ◽  
T Cell Repertoire ◽  
Cell Repertoire ◽  
Repertoire Diversity ◽  
Clonal Composition

Under conditions of impaired T-cell immunity, human cytomegalovirus (HCMV) can reactivate from lifelong latency, resulting in potentially fatal disease. A crucial role for CD8+ T cells has been demonstrated in control of viral replication, and high levels of HCMV-specific cytotoxic T-lymphocytes are seen in immunocompetent HCMV-seropositive individuals despite very low viral loads. Elucidation of the minimum portion of the anti-HCMV T-cell repertoire that is required to suppress viral replication requires further study of clonal composition. The ability of dendritic cells to take up and process exogenous viral antigen by constitutive macropinocytosis was used to study HCMV-specific T-cell memory in the absence of viral replication. The specificity and clonal composition of the CD8+ T-cell responses were evaluated using HLA tetrameric complexes and T-cell receptor β chain (TCRBV) spectratypic analyses. There was a skewed reactivity toward the matrix protein pp65, with up to 40-fold expansion of CD8+ T cells directed toward a single peptide-MHC combination. Individual expansions detected on TCRBV spectratype analysis were HCMV-specific and composed of single or highly restricted numbers of clones. There was preferential TCRBV gene usage (BV6.1/6.2, BV8, and BV13 in HLA-A*0201+ individuals) but lack of conservation of CDR3 length and junctional motifs between donors. While there was a spectrum of TCR repertoire diversity directed toward individual MHC-peptide combinations between donors, a relatively small number of clones appeared to predominate the response in each case. These data provide further insight into the range of anti-HCMV responses and will aid the design and monitoring of adoptive immunotherapy protocols.

scholarly journals Sunitinib Exerts In Vitro Immunomodulatory Activity on Sarcomas via Dendritic Cells and Synergizes With PD-1 Blockade

2021 ◽  
Vol 12 ◽  
Author(s):  
Darina Ocadlikova ◽  
Mariangela Lecciso ◽  
Javier Martin Broto ◽  
Katia Scotlandi ◽  
Michele Cavo ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Cell Lines ◽  
Effector T Cells ◽  
Sarcoma Cell ◽  
Ifn Γ ◽  
Sarcoma Cells

BackgroundHigh-grade sarcomas are a heterogeneous group of aggressive tumors arising in bone and soft tissues. After relapse, treatment options are limited. The multi-targeted receptor tyrosine kinase inhibitors (TKIs) sunitinib and inhibitor of PD-1 (anti-PD-1) nivolumab have shown antitumor activity in selected subtypes. In this study, we examine the role of TKIs and PD-1 based therapy in in vitro cocultures of sarcoma.MethodsThe human osteosarcoma (SaOS-2) and synovial sarcoma (SYO-1) cell lines were treated with sunitinib. After cell death and proliferation assessment, expression of PD-L1 was analyzed by flow cytometry. Sunitinib-treated sarcoma cells were cocultured with dendritic cells (DCs), and the phenotype of mature DCs was determined by flow cytometry. Mature DCs were cultured with autologous T cells. PD-1 expression on T cells, their proliferation, T regulatory cell (Tregs) induction and IFN-γ production, before and after nivolumab exposure, were analyzed.ResultsAlong with its anti-proliferative and direct pro-apoptotic effect on sarcoma cell lines, sunitinib prompted PD-L1 upregulation on sarcoma cells. Interestingly, sunitinib-treated sarcoma cells drive DCs to full maturation and increase their capacity to induce sarcoma-reactive T cells to produce IFN-γ. Conversely, no effect on T cell proliferation and T cell subpopulation composition was observed. Moreover, both bone and synovial sarcoma cell lines induced Tregs through DCs but sunitinib treatment completely abrogated Treg induction. Finally, sarcoma cell lines induced PD-1 upregulation on both effector T cells and Tregs when loaded into DCs, providing a rationale for using PD-1 blockade. Indeed, PD-1 blockade by nivolumab synergized with sunitinib in inducing IFN-γ-producing effector T cells.ConclusionsTaken together, our in vitro data indicate that the treatment of sarcoma cells with sunitinib can exert significant changes on immune cell subsets toward immune activation, leading to DC-based cross-priming of IFN-γ-producing effector T cells and reduced Treg induction. PD-1 blockade with nivolumab has a synergistic effect with sunitinib, supporting the use of TKI and anti-PD-1 approach in sarcomas, and perhaps in other cancers. DC-targeted drugs, including toll-like receptor 3 inhibitors and CD47 inhibitors, are under development and our preclinical model might help to better design their clinical application.

scholarly journals Generation of Human CD8 T Regulatory Cells by CD40 Ligand–activated Plasmacytoid Dendritic Cells

2002 ◽  
Vol 195 (6) ◽  
pp. 695-704 ◽  
Author(s):  
Michel Gilliet ◽  
Yong-Jun Liu
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Transforming Growth Factor ◽  
Cd8 T Cell ◽  
Cd40 Ligand ◽  
Plasmacytoid Dendritic Cells ◽  
Target Cells ◽  
Ifn Γ

Although CD8 T cell–mediated immunosuppression has been a well-known phenomenon during the last three decades, the nature of primary CD8 T suppressor cells and the mechanism underlying their generation remain enigmatic. We demonstrated that naive CD8 T cells primed with allogeneic CD40 ligand–activated plasmacytoid dendritic cells (DC)2 differentiated into CD8 T cells that displayed poor secondary proliferative and cytolytic responses. By contrast, naive CD8 T cells primed with allogeneic CD40 ligand–activated monocyte-derived DCs (DC1) differentiated into CD8 T cells, which proliferated to secondary stimulation and killed allogeneic target cells. Unlike DC1-primed CD8 T cells that produced large amounts of interferon (IFN)-γ upon restimulation, DC2-primed CD8 T cells produced significant amounts of interleukin (IL)-10, low IFN-γ, and no IL-4, IL-5, nor transforming growth factor (TGF)-β. The addition of anti–IL-10–neutralizing monoclonal antibodies during DC2 and CD8 T cell coculture, completely blocked the generation of IL-10–producing anergic CD8 T cells. IL-10–producing CD8 T cells strongly inhibit the allospecific proliferation of naive CD8 T cells to monocytes, and mature and immature DCs. This inhibition was mediated by IL-10, but not by TGF-β. IL-10–producing CD8 T cells could inhibit the bystander proliferation of naive CD8 T cells, provided that they were restimulated nearby to produce IL-10. IL-10–producing CD8 T cells could not inhibit the proliferation of DC1-preactivated effector T cells. This study demonstrates that IL-10–producing CD8 T cells are regulatory T cells, which provides a cellular basis for the phenomenon of CD8 T cell–mediated immunosuppression and suggests a role for plasmacytoid DC2 in immunological tolerance.

scholarly journals Transcription factor Etv6 regulates functional differentiation of cross-presenting classical dendritic cells

2018 ◽  
Vol 215 (9) ◽  
pp. 2265-2278 ◽  
Author(s):  
Colleen M. Lau ◽  
Ioanna Tiniakou ◽  
Oriana A. Perez ◽  
Margaret E. Kirkling ◽  
George S. Yap ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
Transcription Factor ◽  
T Cell ◽  
Cd8 T Cells ◽  
Functional Differentiation ◽  
Specific Gene ◽  
Hematopoietic Stem

An IRF8-dependent subset of conventional dendritic cells (cDCs), termed cDC1, effectively cross-primes CD8+ T cells and facilitates tumor-specific T cell responses. Etv6 is an ETS family transcription factor that controls hematopoietic stem and progenitor cell (HSPC) function and thrombopoiesis. We report that like HSPCs, cDCs express Etv6, but not its antagonist, ETS1, whereas interferon-producing plasmacytoid dendritic cells (pDCs) express both factors. Deletion of Etv6 in the bone marrow impaired the generation of cDC1-like cells in vitro and abolished the expression of signature marker CD8α on cDC1 in vivo. Moreover, Etv6-deficient primary cDC1 showed a partial reduction of cDC-specific and cDC1-specific gene expression and chromatin signatures and an aberrant up-regulation of pDC-specific signatures. Accordingly, DC-specific Etv6 deletion impaired CD8+ T cell cross-priming and the generation of tumor antigen–specific CD8+ T cells. Thus, Etv6 optimizes the resolution of cDC1 and pDC expression programs and the functional fitness of cDC1, thereby facilitating T cell cross-priming and tumor-specific responses.

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