scholarly journals Immunization with host-type CD8α+ dendritic cells reduces experimental acute GVHD in an IL-10–dependent manner

Blood ◽  
2010 ◽  
Vol 115 (3) ◽  
pp. 724-735 ◽  
Author(s):  
Tomomi Toubai ◽  
Chelsea Malter ◽  
Isao Tawara ◽  
Chen Liu ◽  
Evelyn Nieves ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
Major Histocompatibility Complex ◽  
T Cell ◽  
Immune Responses ◽  
T Cell Responses ◽  
Class Ii ◽  
Cell Responses ◽  
Histocompatibility Complex

Abstract Little is known about the role of active immunization in suppressing undesirable immune responses. Because CD8α+ dendritic cells (DCs) suppress certain immune responses, we tested the hypothesis that immunization of donors with host-derived CD8α+ DCs will reduce host-specific donor T-cell responses. BALB/c T cells from the animals that were immunized with B6 CD8α+ DCs demonstrated, in vitro and in vivo, significantly reduced proliferation and secretion of inflammatory cytokines but showed enhanced secretion of interleukin-10 (IL-10). The responses against third-party and model antigens were preserved demonstrating antigen specificity. The in vivo relevance was further demonstrated by the reduction on graft-versus-host disease (GVHD) in both a major histocompatibility complex–mismatched clinically relevant BALB/c → B6 model and major histocompatibility complex–matched, minor-mismatched C3H.SW → B6 model of GVHD. Immunization of the donors that were deficient in IL-10 (IL-10−/−) or with CD8α+ DCs from B6 class II (class II−/−) failed to reduce T-cell responses, demonstrating (1) a critical role for secretion of IL-10 by donor T cells and (2) a direct contact between the T cells and the CD8α+ DCs. Together, these data may represent a novel strategy for reducing GVHD and suggest a broad counterintuitive role for vaccination strategies in mitigating undesirable immune responses in an antigen-specific manner.

scholarly journals Endogenous dendritic cells mediate the effects of intravenously injected therapeutic immunosuppressive dendritic cells in transplantation

Blood ◽  
2010 ◽  
Vol 116 (15) ◽  
pp. 2694-2705 ◽  
Author(s):  
Sherrie J. Divito ◽  
Zhiliang Wang ◽  
William J. Shufesky ◽  
Quan Liu ◽  
Olga A. Tkacheva ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Indirect Pathway ◽  
Allograft Survival ◽  
Complex Molecules ◽  
Cell Responses ◽  
Histocompatibility Complex

Abstract The prevailing idea regarding the mechanism(s) by which therapeutic immunosuppressive dendritic cells (DCs) restrain alloimmunity is based on the concept that they interact directly with antidonor T cells, inducing anergy, deletion, and/or regulation. However, this idea has not been tested in vivo. Using prototypic in vitro–generated maturation-resistant (MR) DCs, we demonstrate that once MR-DCs carrying donor antigen (Ag) are administered intravenously, they decrease the direct and indirect pathway T-cell responses and prolong heart allograft survival but fail to directly regulate T cells in vivo. Rather, injected MR-DCs are short-lived and reprocessed by recipient DCs for presentation to indirect pathway CD4+ T cells, resulting in abortive activation and deletion without detrimental effect on the number of indirect CD4+ FoxP3+ T cells, thus increasing the regulatory to effector T cell relative percentage. The effect on the antidonor response was independent of the method used to generate therapeutic DCs or their viability; and in accordance with the idea that recipient Ag-presenting cells mediate the effects of therapeutic DCs in transplantation, prolongation of allograft survival was achieved using donor apoptotic MR-DCs or those lacking surface major histocompatibility complex molecules. We therefore conclude that therapeutic DCs function as Ag-transporting cells rather than Ag-presenting cells to prolong allograft survival.

scholarly journals Immune Responses in Perforin Deficient Mice

2021 ◽  
Author(s):  
◽  
Helen Mary Alys Simkins
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Influenza Infection ◽  
T Cell Responses ◽  
Nkt Cells ◽  
T Cell Response ◽  
Dependent Manner ◽  
Cell Responses

<p>Dendritic cells (DC) play a pivotal role in the initiation of T cell responses and earlier studies have shown that their survival is important for the generation of effective immune responses. Cytotoxic T lymphocytes (CTL) and natural killer T (NKT) cells have been proposed to regulate the survival of antigen presenting DC through their ability to kill cells expressing specific antigen via secretion of perforin, a protein contained in cytotoxic granules. Perforin knockout (PKO) mice generate amplified immune responses to DC immunization, suggesting a link between defective cytotoxicity and increased T cell responses. The studies in this thesis used PKO mice and in vivo models of CD8+T cells and NKT cell immune responses to determine whether CTL and NKT cells eliminate DC in a perforin-dependent manner, and whether DC elimination is a mechanism to regulate T cell responses. During a primary influenza infection C57BL/6 and PKO mice generated a similar influenza specific CD8+ immune response. No significant difference in the percentage of influenza epitope PA224-233 specific T cells was observed between C57BL/6 and PKO mice during a secondary influenza infection, but PKO mice had a significantly reduced T cell response directed towards the dominant influenza epitope, NP366-374. The reduced T cell response in PKO mice was not due to differences in activation or differentiation status of specific T cells compared to C57BL/6 mice. Therefore, the extended DC survival in PKO after secondary influenza viral infection, recently reported by other authors, does not appear to correlate with increased expansion of virus specific CD8+T cells in infected mice. The role of NKT cells in DC elimination was assessed in vivo using the NKT cell ligand a-Galactosylceramide (a-GalCer). Injection of a-GalCer in C57BL/6 mice induced a dramatic decline in the number of splenic CD8+DC. A similar decrease in CD8+DC numbers was observed in PKO mice, suggesting that the mechanism of DC loss did not involve perforinmediated killing. In contrast, treatment with a TNF-a neutralizing antibody substantially reduced the decline in CD8+DC numbers. This reduction in splenic CD8+DC occurred as early as 15 hr after a-GalCer treatment, and did not affect generation of CD8+T cell responses or the ability of a-GalCer treatment to provide tumour protection. Taken together, these results suggest that multiple cells and mechanisms can regulate DC survival in vivo. CTL regulate DC survival in vivo in a perforin-dependent manner, but this does not necessarily affect the magnitude of the resulting immune responses. NKT cells also affect the survival of DC in vivo, but in a perforin-independent, cytokine-dependent manner. These findings provide additional knowledge about the in vivo involvement of perforin in regulating DC survival by CTL and NKT cells and the effects this has on T cell responses.</p>

scholarly journals Immune Responses in Perforin Deficient Mice

2021 ◽  
Author(s):  
◽  
Helen Mary Alys Simkins
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Influenza Infection ◽  
T Cell Responses ◽  
Nkt Cells ◽  
T Cell Response ◽  
Dependent Manner ◽  
Cell Responses

<p>Dendritic cells (DC) play a pivotal role in the initiation of T cell responses and earlier studies have shown that their survival is important for the generation of effective immune responses. Cytotoxic T lymphocytes (CTL) and natural killer T (NKT) cells have been proposed to regulate the survival of antigen presenting DC through their ability to kill cells expressing specific antigen via secretion of perforin, a protein contained in cytotoxic granules. Perforin knockout (PKO) mice generate amplified immune responses to DC immunization, suggesting a link between defective cytotoxicity and increased T cell responses. The studies in this thesis used PKO mice and in vivo models of CD8+T cells and NKT cell immune responses to determine whether CTL and NKT cells eliminate DC in a perforin-dependent manner, and whether DC elimination is a mechanism to regulate T cell responses. During a primary influenza infection C57BL/6 and PKO mice generated a similar influenza specific CD8+ immune response. No significant difference in the percentage of influenza epitope PA224-233 specific T cells was observed between C57BL/6 and PKO mice during a secondary influenza infection, but PKO mice had a significantly reduced T cell response directed towards the dominant influenza epitope, NP366-374. The reduced T cell response in PKO mice was not due to differences in activation or differentiation status of specific T cells compared to C57BL/6 mice. Therefore, the extended DC survival in PKO after secondary influenza viral infection, recently reported by other authors, does not appear to correlate with increased expansion of virus specific CD8+T cells in infected mice. The role of NKT cells in DC elimination was assessed in vivo using the NKT cell ligand a-Galactosylceramide (a-GalCer). Injection of a-GalCer in C57BL/6 mice induced a dramatic decline in the number of splenic CD8+DC. A similar decrease in CD8+DC numbers was observed in PKO mice, suggesting that the mechanism of DC loss did not involve perforinmediated killing. In contrast, treatment with a TNF-a neutralizing antibody substantially reduced the decline in CD8+DC numbers. This reduction in splenic CD8+DC occurred as early as 15 hr after a-GalCer treatment, and did not affect generation of CD8+T cell responses or the ability of a-GalCer treatment to provide tumour protection. Taken together, these results suggest that multiple cells and mechanisms can regulate DC survival in vivo. CTL regulate DC survival in vivo in a perforin-dependent manner, but this does not necessarily affect the magnitude of the resulting immune responses. NKT cells also affect the survival of DC in vivo, but in a perforin-independent, cytokine-dependent manner. These findings provide additional knowledge about the in vivo involvement of perforin in regulating DC survival by CTL and NKT cells and the effects this has on T cell responses.</p>

scholarly journals Species specificity and augmentation of responses to class II major histocompatibility complex molecules in human CD4 transgenic mice.

1992 ◽  
Vol 175 (6) ◽  
pp. 1707-1715 ◽  
Author(s):  
E Barzaga-Gilbert ◽  
D Grass ◽  
S K Lawrance ◽  
P A Peterson ◽  
E Lacy ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
Major Histocompatibility Complex ◽  
T Cell ◽  
Class Ii ◽  
T Cell Proliferation ◽  
Human Class ◽  
Cell Responses ◽  
Histocompatibility Complex ◽  
Species Specific

Murine T cell responses to human class II major histocompatibility complex (MHC) molecules were shown to be a minimum of 20-70-fold lower than responses to allogeneic molecules. Transgenic mice expressing slightly below normal (75-95%) or very high (250-380%) cell surface levels of human CD4 were utilized to determine whether this was due to a species-specific interaction between murine CD4 and class II molecules. Human CD4 was shown to function in signal transduction events in murine T cells based on the ability of anti-human CD4 antibody to synergize with suboptimal doses of anti-murine CD3 antibody in stimulating T cell proliferation. In mice expressing lower levels of human CD4, T cell responses to human class II molecules were enhanced up to threefold, whereas allogeneic responses were unaltered. In mice expressing high levels of human CD4, responses to human class II molecules were enhanced at least 10-fold, whereas allogeneic responses were between one and three times the level of normal responses. The relatively greater enhancement of the response to human class II molecules in both lines argues for a preferential interaction between human CD4 and human class II molecules. In mice expressing lower levels of human CD4, responses to human class II molecules were blocked by antibodies to CD4 of either species, indicating participation by both molecules. In mice expressing high levels of human CD4, responses to both human and murine class II molecules were almost completely blocked with anti-human CD4 antibody, whereas anti-murine CD4 antibody had no effect. However, anti-murine CD4 continued to synergize with anti-CD3 in stimulating T cell proliferation in these mice. Thus, overexpression of human CD4 selectively impaired the ability of murine CD4 to assist in the process of antigen recognition. The ability of human CD4 to support a strong allogeneic response under these conditions indicates that this molecule can interact with murine class II molecules to a significant extent. Despite the fact that human CD4 appeared to be the only functional coreceptor in these mice, responses to human class II molecules were still much lower than those to murine class II alloantigens. This indicates that species-specific interactions between class II molecules and CD4 expressed on peripheral T cells are not sufficient to account for the low xenogeneic response and that intrinsic differences in T cell receptor structures or the need for species specificity in the interaction between CD4 and class II molecules during positive selection are also important.

T Cell Responses in Patients Vaccinated with Telomerase (hTERT)-mRNA Transfected Dendritic Cells.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 373-373
Author(s):  
Else Marit Inderberg Suso ◽  
Anne-Marie Rasmussen ◽  
Steinar Aamdal ◽  
Svein Dueland ◽  
Gustav Gaudernack ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Immune Responses ◽  
Cancer Patients ◽  
Cd8 T Cells ◽  
Stable Disease ◽  
T Cell Responses ◽  
Htert Mrna ◽  
Cell Responses

Abstract Abstract 373 Two cancer patients were vaccinated with dendritic cells (DC) loaded with telomerase (hTERT) mRNA to investigate the safety, tolerability and immunological response to vaccination prior to the start of a new phase I/II clinical trial. Following written informed consent one primary lung adenocarcinoma with metastasis and one patient with a relapsed pancreatic ductal type of adenocarcinoma, were treated with autologus monocyte-derived DC transfected with mRNA encoding hTERT. The patients first received four weekly injections administered intradermally followed by monthly booster injections. Peripheral blood mononuclear cells (PBMC) at each vaccination time point were tested in vitro with transfected DC and a panel of 24 overlapping hTERT peptides. In addition, hTERT-specific CD8+ T cells were monitored by pentamer staining. The treatment was well tolerated with minor side effects. Immune responses against telomerase-transfected DC and some of the overlapping hTERT peptides were detected in both patients. We also detected hTERT-specific CD8+ T cells in both patients by pentamer staining in post-vaccination samples. The lung cancer patients obtained a stable disease that lasted 18 months while the patient with pancreas cancer who started the DC vaccination in July 2007 following palliative chemotherapy, still is in stable disease by continuously boost vaccination. T-cell responses against telomerase epitopes have also been identified in both non-vaccinated cancer patients and cancer patients previously vaccinated with telomerase peptide. Since patients with these findings often show extraordinary clinical courses of their disease we hypothesize that it exists a high degree of immunogenicity and HLA promiscuity for some telomerase epitopes. In this study we have shown that vaccination with hTERT-mRNA transfected DC is safe and able to induce robust immune responses to several telomerase T-cell epitopes both in CD4+ and CD8+ T cells. This opens up the possibility for a broad clinical application of mRNA hTERT DC vaccines. Furthermore, responding T cells identified in these patients are strong candidates for T-cell receptor cloning and the receptors identified can thereafter be transferred into T cells creating the next generation of immuno-gene therapy with retargeted T cells. Disclosures: No relevant conflicts of interest to declare.

ICAM-1 on exosomes from mature dendritic cells is critical for efficient naive T-cell priming

Blood ◽  
2005 ◽  
Vol 106 (1) ◽  
pp. 216-223 ◽  
Author(s):  
Elodie Segura ◽  
Carole Nicco ◽  
Bérangère Lombard ◽  
Philippe Véron ◽  
Graça Raposo ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Mhc Class Ii ◽  
T Cell Responses ◽  
Class Ii ◽  
Naive T Cells ◽  
Naïve T Cells ◽  
Cell Responses

Exosomes are secreted vesicles formed in late endocytic compartments. Immature dendritic cells (DCs) secrete exosomes, which transfer functional major histocompatibility complex (MHC)–peptide complexes to other DCs. Since immature and mature DCs induce different functional T-cell responses (ie, tolerance versus priming), we asked whether DC maturation also influenced the priming abilities of their exosomes. We show that exosomes secreted by lipopolysaccharide (LPS)–treated mature DCs are 50- to 100-fold more potent to induce antigen-specific T-cell activation in vitro than exosomes from immature DCs. In vitro, exosomes from mature DCs transfer to B lymphocytes the ability to prime naive T cells. In vivo, only mature exosomes trigger effector T-cell responses, leading to fast skin graft rejection. Proteomic and biochemical analyses revealed that mature exosomes are enriched in MHC class II, B7.2, intercellular adhesion molecule 1 (ICAM-1), and bear little milk-fat globule–epidermal growth factor–factor VIII (MFG-E8) as compared with immature exosomes. Functional analysis using DC-derived exosomes from knock-out mice showed that MHC class II and ICAM-1 are required for mature exosomes to prime naive T cells, whereas B7.2 and MFG-E8 are dispensable. Therefore, changes in protein composition and priming abilities of exosomes reflect the maturation signals received by DCs.

scholarly journals Interleukin-12p70 Expression by Dendritic Cells of HIV-1-Infected Patients Fails to Stimulategag-Specific Immune Responses

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Ellen Van Gulck ◽  
Nathalie Cools ◽  
Derek Atkinson ◽  
Lotte Bracke ◽  
Katleen Vereecken ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Immune Responses ◽  
T Cell Responses ◽  
Hiv Replication ◽  
Cell Responses ◽  
Antigen Presenting ◽  
Hiv 1 ◽  
Unique Capability

A variety of immune-based therapies has been developed in order to boost or induce protective CD8+T cell responses in order to control HIV replication. Since dendritic cells (DCs) are professional antigen-presenting cells (APCs) with the unique capability to stimulate naïve T cells into effector T cells, their use for the induction of HIV-specific immune responses has been studied intensively. In the present study we investigated whether modulation of the activation state of DCs electroporated with consensus codon-optimized HxB2gagmRNA enhances their capacity to induce HIVgag-specific T cell responses. To this end, mature DCs were (i) co-electroporated with mRNA encoding interleukin (IL)-12p70 mRNA, or (ii) activated with a cytokine cocktail consisting of R848 and interferon (IFN)-γ. Our results confirm the ability of HxB2gag-expressing DCs to expand functional HIV-specific CD8+T cells. However, although most of the patients had detectablegag-specific CD8+T cell responses, no significant differences in the level of expansion of functional CD8+T cells could be demonstrated when comparing conventional or immune-modulated DCs expressing IL-12p70. This result which goes against expectation may lead to a re-evaluation of the need for IL-12 expression by DCs in order to improve T-cell responses in HIV-1-infected individuals.

scholarly journals Functional analysis of peripheral and intratumoral neoantigen-specific TCRs identified in a patient with melanoma

2021 ◽  
Vol 9 (9) ◽  
pp. e002754
Author(s):  
Eva Bräunlein ◽  
Gaia Lupoli ◽  
Franziska Füchsl ◽  
Esam T Abualrous ◽  
Niklas de Andrade Krätzig ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Immune Checkpoint ◽  
T Cell Responses ◽  
Functional Avidity ◽  
Cell Responses

BackgroundNeoantigens derived from somatic mutations correlate with therapeutic responses mediated by treatment with immune checkpoint inhibitors. Neoantigens are therefore highly attractive targets for the development of therapeutic approaches in personalized medicine, although many aspects of their quality and associated immune responses are not yet well understood. In a case study of metastatic malignant melanoma, we aimed to perform an in-depth characterization of neoantigens and respective T-cell responses in the context of immune checkpoint modulation.MethodsThree neoantigens, which we identified either by immunopeptidomics or in silico prediction, were investigated using binding affinity analyses and structural simulations. We isolated seven T-cell receptors (TCRs) from the patient’s immune repertoire recognizing these antigens. TCRs were compared in vitro by multiparametric analyses including functional avidity, multicytokine secretion, and cross-reactivity screenings. A xenograft mouse model served to study in vivo functionality of selected TCRs. We investigated the patient’s TCR repertoire in blood and different tumor-related tissues over 3 years using TCR beta deep sequencing.ResultsSelected mutated peptide ligands with proven immunogenicity showed similar binding affinities to the human leukocyte antigen complex and comparable disparity to their wild-type counterparts in molecular dynamic simulations. Nevertheless, isolated TCRs recognizing these antigens demonstrated distinct patterns in functionality and frequency. TCRs with lower functional avidity showed at least equal antitumor immune responses in vivo. Moreover, they occurred at high frequencies and particularly demonstrated long-term persistence within tumor tissues, lymph nodes and various blood samples associated with a reduced activation pattern on primary in vitro stimulation.ConclusionsWe performed a so far unique fine characterization of neoantigen-specific T-cell responses revealing defined reactivity patterns of neoantigen-specific TCRs. Our data highlight qualitative differences of these TCRs associated with function and longevity of respective T cells. Such features need to be considered for further optimization of neoantigen targeting including adoptive T-cell therapies using TCR-transgenic T cells.

scholarly journals Francisella tularensis Induces Ubiquitin-Dependent Major Histocompatibility Complex Class II Degradation in Activated Macrophages

2009 ◽  
Vol 77 (11) ◽  
pp. 4953-4965 ◽  
Author(s):  
Justin E. Wilson ◽  
Bhuvana Katkere ◽  
James R. Drake
Keyword(s):  
T Cells ◽  
Major Histocompatibility Complex ◽  
T Cell ◽  
Mhc Class Ii ◽  
Francisella Tularensis ◽  
Class Ii ◽  
Activated Macrophages ◽  
Cell Responses ◽  
Histocompatibility Complex ◽  
Ifn Γ

ABSTRACT The intracellular bacterium Francisella tularensis survives and replicates within macrophages, ultimately killing the host cell. Resolution of infection requires the development of adaptive immunity through presentation of F. tularensis antigens to CD4+ and CD8+ T cells. We have previously established that F. tularensis induces macrophage prostaglandin E2 (PGE2) production, leading to skewed T-cell responses. PGE2 can also downregulate macrophage major histocompatibility complex (MHC) class II expression, suggesting that F. tularensis-elicited PGE2 may further alter T-cell responses via inhibition of class II expression. To test this hypothesis, gamma interferon (IFN-γ)-activated reporter macrophages were exposed to supernatants from F. tularensis-infected macrophages, and the class II levels were measured. Exposure of macrophages to infection supernatants results in essentially complete clearance of surface class II and CD86, compromising the macrophage's ability to present antigens to CD4 T cells. Biochemical analysis revealed that infection supernatants elicit ubiquitin-dependent class II downregulation and degradation within intracellular acidic compartments. By comparison, exposure to PGE2 alone only leads to a minor decrease in macrophage class II expression, demonstrating that a factor distinct from PGE2 is eliciting the majority of class II degradation. However, production of this non-PGE2 factor is dependent on macrophage cyclooxygenase activity and is induced by PGE2. These results establish that F. tularensis induces the production of a PGE2-dependent factor that elicits MHC class II downregulation in IFN-γ-activated macrophages through ubiquitin-mediated delivery of class II to lysosomes, establishing another mechanism for the modulation of macrophage antigen presentation during F. tularensis infection.

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