scholarly journals Regulatory Dendritic Cells, T Cell Tolerance, and Dendritic Cell Therapy for Immunologic Disease

2021 ◽  
Vol 12 ◽  
Author(s):  
Sara Ness ◽  
Shiming Lin ◽  
John R. Gordon
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Surrogate Marker ◽  
T Cell Responses ◽  
T Cell Tolerance ◽  
Cell Tolerance ◽  
Cell Responses ◽  
The Impact

Dendritic cells (DC) are antigen-presenting cells that can communicate with T cells both directly and indirectly, regulating our adaptive immune responses against environmental and self-antigens. Under some microenvironmental conditions DC develop into anti-inflammatory cells which can induce immunologic tolerance. A substantial body of literature has confirmed that in such settings regulatory DC (DCreg) induce T cell tolerance by suppression of effector T cells as well as by induction of regulatory T cells (Treg). Many in vitro studies have been undertaken with human DCreg which, as a surrogate marker of antigen-specific tolerogenic potential, only poorly activate allogeneic T cell responses. Fewer studies have addressed the abilities of, or mechanisms by which these human DCreg suppress autologous effector T cell responses and induce infectious tolerance-promoting Treg responses. Moreover, the agents and properties that render DC as tolerogenic are many and varied, as are the cells’ relative regulatory activities and mechanisms of action. Herein we review the most current human and, where gaps exist, murine DCreg literature that addresses the cellular and molecular biology of these cells. We also address the clinical relevance of human DCreg, highlighting the outcomes of pre-clinical mouse and non-human primate studies and early phase clinical trials that have been undertaken, as well as the impact of innate immune receptors and symbiotic microbial signaling on the immunobiology of DCreg.

scholarly journals Batf3-Dependent Dendritic Cells Promote Optimal CD8 T Cell Responses against Respiratory Poxvirus Infection

2018 ◽  
Vol 92 (16) ◽  
Author(s):  
Pritesh Desai ◽  
Vikas Tahiliani ◽  
Georges Abboud ◽  
Jessica Stanfield ◽  
Shahram Salek-Ardakani
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Vaccinia Virus ◽  
Respiratory Infection ◽  
Host Resistance ◽  
T Cell Responses ◽  
Cell Responses ◽  
Ifn Γ ◽  
The Impact

ABSTRACTRespiratory infection with vaccinia virus (VacV) elicits robust CD8+T cell responses that play an important role in host resistance. In the lung, VacV encounters multiple tissue-resident antigen-presenting cell (APC) populations, but which cell plays a dominant role in priming of virus-specific CD8+effector T cell responses remains poorly defined. We used Batf3−/−mice to investigate the impact of CD103+and CD8α+dendritic cell (DC) deficiency on anti-VacV CD8+T cell responses. We found that Batf3−/−mice were more susceptible to VacV infection, exhibiting profound weight loss, which correlated with impaired accumulation of gamma interferon (IFN-γ)-producing CD8+T cells in the lungs. This was largely due to defective priming since early in the response, antigen-specific CD8+T cells in the draining lymph nodes of Batf3−/−mice expressed significantly reduced levels of Ki67, CD25, and T-bet. These results underscore a specific role for Batf3-dependent DCs in regulating priming and expansion of effector CD8+T cells necessary for host resistance against acute respiratory VacV infection.IMPORTANCEDuring respiratory infection with vaccinia virus (VacV), a member ofPoxviridaefamily, CD8+T cells play important role in resolving the primary infection. Effector CD8+T cells clear the virus by accumulating in the infected lungs in large numbers and secreting molecules such as IFN-γ that kill virally infected cells. However, precise cell types that regulate the generation of effector CD8+T cells in the lungs are not well defined. Dendritic cells (DCs) are a heterogeneous population of immune cells that are recognized as key initiators and regulators of T-cell-mediated immunity. In this study, we reveal that a specific subset of DCs that are dependent on the transcription factor Batf3 for their development regulate the magnitude of CD8+T cell effector responses in the lungs, thereby providing protection during pulmonary VacV infection.

Transfection of Dendritic Cells with In Vitro Transcribed RNA Induces Polyclonal CMV-Specific CD8+ and CD4+ Mediated T Cell Responses.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1354-1354
Author(s):  
Annkristin Heine ◽  
Tobias Holderried ◽  
Frank Grünebach ◽  
Silke Appel ◽  
Markus M. Weck ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Cell Response ◽  
Cytotoxic T Cells ◽  
T Cell Responses ◽  
T Cell Response ◽  
Cell Responses ◽  
Rna Transfection

Abstract Transfection of dendritic cells (DC) with in vitro transcribed RNA was shown to be a highly efficient method to generate antigen specific T cells, probably due to the induction of a polyclonal T cell response directed against multiple antigens presented on different HLA allels. However, the experimental evidence of this assumption remains to be demonstrated. To accomplish this, we used monocyte derived DC that were electroporated with RNA coding for the CMV pp65 antigen. The induction and expansion of antigen specific CD8+ and CD4+ T cells was assessed using a pannel of peptides derived from this antigen and presented on HLA-A2, -A1, -A11, -A24, -B35 and -B7 in IFN-g ELISPOT, 51Cr-release and proliferation assays. Autologous DC generated from CMV positive healthy donors were pulsed with peptides or transfected with pp65 RNA and utilized as stimulators. Autologous purified CD8+ and CD4+ lymphocytes were used as effector cells. By applying this approach we found that transfection of DC with pp65 RNA induces an expansion of polyclonal CD8+ mediated T cell responses that recognized peptide antigens presented on different HLA molecules. These in vitro generated cytotoxic T cells were able to efficiently lyse DC pulsed with pp65 derived peptides or transfected with the cognate RNA in an antigen specific manner after several in vitro restimulations. Furthermore, this experimental approach allowed the identification of the immunodominace of T cell epitopes presented upon RNA transfection. The HLA-2 directed responses were more pronounced as compared to the HLA-A1, -A11, -A24 or -B35 allels. In contrast, in 7 out of 7 HLA-A2 and HLA-B7 positive donors B7-peptides elicited a stronger T cell response than the A2-peptide, indicating the immunodominance of HLA-B7 epitopes. Interestingly, transfection of DC with pp65 RNA resulted in the induction of CD4+ antigen specific T cells that produced IFN-g and proliferated upon stimulation with transfected DC. In the next set of experiments we analyzed the possible induction of CMV specific T cells that recognize epitopes deduced from different antigens. Co-transfection of DC with a mixture of RNAs coding for the CMV pp65 and IE1 antigens elicited polyclonal T lymphocytes specific for peptides derived from both antigens. More importantly, polyclonal cytotoxic T cells could be elicited in peripheral blood of 2 out of 3 CMV negative donors demonstrating the efficiency of this approach. Our results demonstrate that DC transfected with RNA can elicit polyclonal T cell responses and have implications for the development of immunotherapeutic strategies to target viral or tumor associated antigens.

The Immunomodulatory Drug Lenalidomide (CC5013; Revlimid), Enhances Antigen-Presenting Cell’s Function Leading to Effective Priming of CD4+ T-Lymphocytes.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2391-2391
Author(s):  
Hongwei Wang ◽  
Aung Naing ◽  
Fengdong Cheng ◽  
Pedro Horna ◽  
Ildelfonso Suarez ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mhc Class Ii ◽  
Immune Tolerance ◽  
T Cell Responses ◽  
T Cell Tolerance ◽  
Cell Tolerance ◽  
Cell Responses ◽  
Cognate Antigen ◽  
Antigen Presenting

Abstract Professional antigen-presenting cells (APCs) play an important role in the initiation of antigen-specific T-cell responses. The demonstration that these cells are also required for the induction of T-cell tolerance, placed APCs at the crossroads of immune activation versus immune tolerance. Recent studies have demonstrated that the inflammatory status of the APC at the time of antigen presentation is the central determinant of T-cell priming versus T-cell tolerance. As such, therapeutic induction of inflammatory APCs might override immune tolerance and enhance the efficacy of immunotherapeutic strategies targeting hematologic tumors. Lenalidomide (CC5013) is a thalidomide analogue with immunomodulatory properties. Phase I and Phase II clinical trials in patients with myelodysplastic syndrome (MDS) have shown high frequency of erythropoietic responses, particularly in patients with 5q31 deletion associated with emergence of polyclonal lymphoid infiltrate in responding patient bone marrows. This observation raised the question as to whether immunological mechanism(s) may mediate, at least in part, the beneficial effect of CC5013 in patients with MDS. To gain further insight into the effects of Lenalidomide on APC’s function and regulation of antigen-specific CD4+ T-cell responses, we treated peritoneal elicited macrophages (PEM) and bone marrow-derived dendritic cells (DCs) with escalating concentration of Lenalidomide in vitro. Enhanced expression of both B7.1 and B7.2 co-stimulatory molecules was observed in Lenalidomide-treated APCs relative to untreated APCs. No difference in the expression of MHC class II molecules or CD40 was detected. Assessment of cytokine production by ELISA showed that Lenalidomide-treated APCs produce higher levels of TNF-a, IL-6 and IL-10 in response to LPS stimulation as compared to untreated APCs. Next, we evaluated the ability of Lenalidomide-treated APCs to present cognate antigen to naïve and tolerant CD4+ T-cells specific for a MHC class II restricted epitope of influenza hemagglutinin (HA). We found that treatment of either PEM or DC with low doses of Lenalidomide (range: 1.5–12.5 uM) significantly enhanced their antigen-presenting capabilities leading to effective priming of naïve CD4+ T-cells confirmed by their increased production of IL-2 and IFN-gamma in response to cognate antigen. Taken together, our results shows that by inducing inflammatory APCs, Lenalidomide directs the outcome of antigen-specific T-cell responses. Furthermore, they have broadened the scope of this drug as a promising adjuvant in cancer immunotherapy.

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 TNFRSF14 aberrations in Follicular Lymphoma B Cells Result in Increased Alloresponses in Vitro and in Vivo

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 2426-2426 ◽  
Author(s):  
Eleni Kotsiou ◽  
Jessica Okosun ◽  
Andrew James Clear ◽  
Sameena Iqbal ◽  
Jude Fitzgibbon ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Lymph Nodes ◽  
Follicular Lymphoma ◽  
T Cell Responses ◽  
Cell Responses ◽  
Significant Difference ◽  
The Impact

Abstract Introduction Genetic aberrations of Tumor Necrosis Factor Receptor Superfamily 14 (TNFRSF14, also known as HVEM) have been shown to occur at high frequencies in patients (pts) with follicular lymphoma (FL). HVEM is a ligand for B and T lymphocyte attenuator (BTLA) which negatively regulates T cell responses and BTLA stimulation reduces acute graft-versus-host disease (aGvHD) in murine allogeneic hematopoietic cell transplantation (AHCT) models. As activated FL B cells are potent alloantigen presenting cells, we hypothesized that TNFRSF14 aberrations in FL B cells would reduce expression of HVEM and potentiate capacity of FL B cells to stimulate allogeneic T cell responses. We therefore sought to determine the functional effect of TNFRSF14 aberrations on FL B cell-stimulated donor T cell alloresponses in vitro. We also examined the impact of TNFRSF14 aberrations on the outcome of FL pts after HLA-matched reduced intensity conditioning (RIC) AHCT. Results FL B cells from lymph nodes were FACS-sorted (>90% purity and > 95% light chain restriction), activated and used as stimulators in mixed lymphocyte reactions with purified allogeneic responder CD3+ T cells. HVEM expression on FL B cells from pts with biallelic TNFRSF14 aberrations (Mut/Del cases) was undetectable whereas 40% of FL B cells from TNFRSF14 WT cases expressed HVEM (Fig 1 A). In contrast, FL B cells from Mut/Del and WT cases expressed similar levels of MHC class I/II, CD80, CD86 and CD58 before and after activation. Allostimulation with Mut/Del FL B cells resulted in significantly greater expression of activation markers on responder CD4+ T cells, increased secretion of pro-inflammatory cytokines (IFN-γ, TNF-α, and IL-2) measured by ELISA and increased frequencies of cytokine-secreting CD4+ and CD8+ T cells enumerated by intracellular cytokine staining. Responder T cell proliferation by thymidine incorporation was significantly greater after stimulation with Mut/Del FL B cells compared to WT FL B cells. CFSE labeling studies demonstrated that this effect resulted from increased proliferation of CD4+ and CD8+ responder T cells after both primary (Fig 1B) and secondary allostimulation. To determine if the increased alloresponses we observed using FL B cells from TNFRSF14 Mut/Del cases was due to reduced HVEM-BTLA signaling, we performed allogeneic co-cultures in the presence of antagonist or agonist BTLA antibodies (ab). Antagonist anti-BTLA ab increased proliferation of responder T cells after stimulation with WT FL B cells confirming that BTLA limits alloresponses in our in vitro model. Importantly, agonist BTLA ab reduced alloresponses stimulated by Mut/Del FL B cells. We next sought to determine if the increased alloresponses we detected in vitro in FL pts with TNFRSF14 aberrations resulted in an increase in clinical alloreactivity after AHCT. DNA from lymph nodes from FL pts undergoing T-cell replete RIC AHSCT was screened for TNFRSF14 mutations and deletions by Sanger sequencing and multiplex ligation-probe amplification respectively. Cumulative incidences (CI) of aGvHD and GvHD-related death were calculated with FL progression as a competing risk. TNFRSF14 aberrations were identified in 10/21 pts prior to RIC AHCT (4 Mut/Del, 1 Del/Del, 1 Mut/WT, 4 Del/WT). Most (18/21) pts had evidence of ongoing FL pre-transplant. Disease and donor characteristics were similar in pts with and without aberrations. There was no significant difference in CI of aGvHD in pts with or without TNFRSF14 aberrations. However there was a significantly higher CI of fatal aGvHD in patients with TNFRSF14 aberrations (45%) compared to those without aberrations (0%, p<0.01). Interestingly, relapse was less frequent in patients with TNFRSF14 aberrations consistent with increased graft-versus-tumor effects, although this did not reach statistical significance. Conclusion This study is the first to describe the impact of TNFRSF14 aberrations on the allostimulatory capacity of FL B cells. TNFRSF14 aberrations were associated with enhanced T-cell alloresponses in vitro and increased death from aGvHD. Importantly, our results suggest FL patients with TNFRSF14 aberrations may benefit from more aggressive immunosuppression to prevent fatal aGvHD after AHCT. The increased antigen-presenting capacity of FL B cells with TNFRSF14 aberrations could also influence autologous anti-tumor responses and impact outcome after other treatment modalities. Figure 1 Figure 1. Disclosures Gribben: Celgene: Research Funding; Pharmacyclics: Honoraria; Roche: Honoraria.

Comparison of Antigen-Loading Strategies for DC-Based Immunotherapy of B-CLL.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4821-4821
Author(s):  
Hakan Mellstedt ◽  
Parviz Kokhaei ◽  
Anders Osterborg ◽  
Aniruddha Choudhury
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Tumor Antigen ◽  
Tumor Antigens ◽  
T Cell Responses ◽  
Pcr Analysis ◽  
Apoptotic Bodies ◽  
Cell Responses

Abstract The slow indolent nature of B-CLL makes it eminently suitable for immune-based treatment strategies. Currently, there exist very few CLL-associated, defined antigen which can be used in vaccination approaches. The use of whole tumor preparations in conjunction with dendritic cells (DC) as cellular adjuvants presents an alternative method for generating therapeutic T-cell responses in CLL patients. We have examined various strategies of loading DC with whole tumor antigens; viz. tumor-DC hybrids, endocytosed apoptotic bodies, RNA or lysate from B-CLL cells. Dendritic cells were generated in vitro, using GM-CSF and IL-4 from immunomagnetically purified, CD14+ monocyte precursors obtained from the peripheral blood of B-CLL patients. The immature DC were loaded with whole tumor antigen using the above methods and matured using TNFα. The tumor antigen-loaded DC were compared for their ability to stimulate autologous T-cell responses. Among all the antigen-loading methods tested, DC that had endocytosed apoptotic bodies (Apo-DC) consistently generated the greatest numbers and magnitude of reactive T-cells as quantified in proliferation and ELISPOT assays. RT-PCR analysis for cytokine mRNA revealed that T-cells stimulated by Apo-DC resulted in an immune response that was almost entirely of the TH1 type as manifested by the production of mRNA for IFN-γ and TNFα. In contrast, other methods of loading antigen resulted in a mixed TH1-TH2 population with varying amounts of TH2 cytokines like IL-4 and IL-10. In a separate series of experiments we compared the T-cell stimulatory capacities of cryopreserved and thawed, with fresh antigen-loaded DC. The results of these studies are essential for the development of a protocol for clinical therapy of B-CLL patients using Apo-DC. Our results indicated that cryopreserved DC could be recovered with high viability. A comparison of functional abilities demonstrated that no significant differences in T-cell stimulatory capacity between cryopreserved and fresh Apo-DC could be noted over a wide variety of immunological assays. Cumulatively, our results suggest that Apo-DC may be a suitable vaccine candidate for immunotherapy of B-CLL patients.

Treatment of Antigen-Presenting Cells with Histone Deacetylase Inhibitors Represents a Novel Strategy To Overcome CD4+ T-Cell Tolerance: Divergent Effects on the IL10 and IL-12 Promoter.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2392-2392
Author(s):  
Hongwei Wang ◽  
Fengdong Cheng ◽  
P. Horna ◽  
I.V. Suarez ◽  
Jian Wu ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
Inflammatory Cytokine ◽  
T Cell Responses ◽  
Cd4 T Cell ◽  
T Cell Tolerance ◽  
Cell Tolerance ◽  
Cell Responses ◽  
Antigen Presenting

Abstract Tumor-antigen-specific T-cell tolerance imposes a significant barrier to the development of effective therapeutic cancer vaccines. Bone marrow-derived antigen presenting cells (APCs) are critical in the induction of this unresponsive state. The requirement for APCs in tolerance induction, together with their well-known role in priming T-cell antitumor responses place APCs at the crossroads of immune activation versus immune tolerance and points to manipulation of these cells as an enticing strategy to modulate T-cell responses against tumors. Identification of the intracellular mechanisms by which APCs induces either T-cell outcome represents therefore a critical step to better understand and overcome tumor-induced immune tolerance. Histones tail plays an important role in modulation of gene transcription. Emerging evidence suggest that inhibition of hystone deacetylases (HDAC) increases the expression of inflammatory genes. Given that the inflammatory status of the APC at the time of antigen presentation is central in determining T-cell priming versus T-cell tolerance, we evaluated the effects of the HDAC inhibitor LAQ842 (Novartis Pharmaceutical Inc.) on APC function and regulation of antigen-specific CD4+ T-cell responses. First, treatment of peritoneal elicited macrophages (PEM) or bone marrow derided dendritic cells (DCs) with increasing concentrations of LAQ842 resulted in enhanced acetylation of hystones H-2A, H-2B, H3 and H4. Analysis of the expression of MHC class molecules and co-stimulatory molecules revealed a significant increase in B7.2 and CD40 in LAQ842-treated APCs as compared to untreated APCs. Utilizing multi-template RNA probes and ELISA we found that LAQ842-treated APCs produce enhanced levels of several inflammatory mediators such as IL-1a, IL-1b, IL-6, TNF-a and RANTES relative to untreated APCs. Similarly, in response to LPS-stimulation, LAQ842-treated APCs produce significant higher levels of the pro-inflammatory cytokine IL-12 but reduce production of the anti-inflammatory cytokine IL-10 as determined by RT-PCR and ELISA. Furthermore, by chromatin immune precipitation (CHIP) assays we found that LAQ842-treated APCs display an increased acetylation of histones associated with the IL-12 promoter but a diminished acetylation of histones at the IL-10 promoter in response to LPS stimulation. Next, we evaluated whether the inflammatory APCs induced by LAQ842 were capable of effectively present antigen and prime productive antigen-specific T-cell responses. In vitro treatment of PEM or DCs with increasing concentrations of LAQ842 resulted in an enhanced presentation of HA-peptide to naïve CD4+ T cells specific for a MHC class II restricted epitope of influenza hemagglutinin (HA). Indeed, these clonotypic T cells display an enhanced HA-specific proliferation, IL-2 and IFN-gamma production relative to clonotypic T cells that encountered HA-antigen on untreated APCs. More importantly, LAQ842-treated APCs were able to restore the responsiveness of tolerant CD4+ T-cells isolated from lymphoma bearing hosts. By demonstrating that HDAC inhibitor induces inflammatory APCs capable of restoring the responsiveness of tolerant T-cells, our studies have unveiled a previously unknown immunological effect of these agents and have broadened their clinical scope as promising adjuvants in cancer immunotherapy.

Ex Vivo Generation Of Functional Plasmacytoid and Myeloid Dendritic Cells Is Strongly Promoted By The Aryl Hydrocarbon Receptor Antagonist Stemregenin 1

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2025-2025
Author(s):  
Soley Thordardottir ◽  
Hangalapura Basav N. ◽  
Tim Hutten ◽  
Marta Cossu ◽  
Jan Spanholtz ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Ex Vivo ◽  
T Cell Responses ◽  
Cell Responses ◽  
Aryl Hydrocarbon ◽  
Hla Dr ◽  
Cd34 Cells

Abstract The prominent role of dendritic cells (DCs) in T cell activation is the rational for DC-based immunotherapy of cancer and infectious diseases. In cancer, DC therapy aims to induce tumor-specific effector T cell responses that can reduce or eliminate the tumor, and to develop immunological memory to control tumor relapse. So far, the vast majority of DC vaccination studies have been performed with DCs differentiated from monocytes (Mo-DCs) that are loaded with tumor-associated antigens (TAAs) or minor histocompatibility antigens (MiHA). This strategy has been reported to induce the expansion of antigen-specific CD4+ and/or CD8+ T cells in the majority of patients, however only a fraction of the patients develop clinical responses. Strategies to improve the potency of DC-based vaccines are to increase the stimulatory and migratory capacity of Mo-DCs, or to use alternative DC subtypes, such as naturally circulating plasmacytoid DCs (pDCs), BDCA1+ myeloid DCs (mDCs) or BDCA3+ mDCs. These DC subsets are potent inducers of antigen-specific T cell responses, and are therefore attractive cells to exploit for DC-based therapy. However, since their frequency in blood is very low, it is a challenge to obtain high enough numbers for immunotherapy. It would be advantageous if DCs, which are phenotypically and functionally similar to blood pDCs and mDCs, could be generated from CD34+ hematopoietic progenitor cells (HPCs). Interestingly, recent findings have indicated that the aryl hydrocarbon receptor (AhR) not only regulates toxic effects of environmental contaminants, but also plays a role in modulating hematopoiesis and the immune system. For instance, it has been reported that StemRegenin 1 (SR1), a small molecule inhibitor of AhR, promotes the ex vivo expansion of human CD34+ HPCs that are able to effectively engraft immunodeficient mice. Furthermore, differentiation of Langerhans cells and monocytes in vitro from HPCs can be inhibited by the addition of the AhR agonist VAF347. In light of these data, we investigated if we could generate DC subsets from CD34+ HPCs by supplementing SR1. Therefore, we cultured CD34+ HPCs in medium containing SCF, Flt3L, IL-6, TPO supplemented with 1 μM SR1 or DMSO as control. Interestingly, addition of SR1 explicitly promoted the emergence of pDCs (CD11c-HLA-DR+CD123hiBDCA2+BDCA4+ cells), BDCA1+ mDCs (Lin1-HLA-DR+BDCA1+BDCA3- cells) and BDCA3+ mDCs (Lin1-HLA-DR+BDCA1-BDCA3+ cells). After three weeks of culture, the frequency of these DC subsets was significantly higher in cultures with SR1 compared to control conditions; 2.9% vs. 0.04% for pDCs, 4.6% vs. 0.5% for BDCA1+ mDCs and 1.1% vs. 0.1% for BDCA3+ mDCs (n=3-5 donors). The average yield after three weeks of culture with SR1 starting from 105 CD34+ UCB cells was 3.8x106 pDCs, 5.3x106 BDCA1+ mDCs and 1.2x106 BDCA3+ mDCs (n=3-5 donors). Furthermore, SR1 also promoted the differentiation of DC subsets from CD34+ cells obtained from peripheral blood of G-CSF-mobilized donors. The average frequency of DCs in these SR1-cultures was 4.7%, 3.8% and 0.9% for pDCs, BDCA1+ and BDCA3+ mDCs, respectively (n=3 donors), which is comparable to the frequency obtained from UCB CD34+ cells. But the expansion potential of G-CSF-mobilized blood CD34+ HPCs was lower than that of UCB CD34+ cells, resulting in average DC yields of 0.6x106, 0.5x106 and 0.1x106 from 105 CD34+ cells (n=3). Flow cytometry analysis demonstrated that the SR1-induced pDCs and mDCs are phenotypically comparable to their naturally occurring counterpart in blood. Furthermore, the ex vivo-generated pDCs potently responded to stimulation with TLR7 and TLR9 ligands by secreting high amounts of IFN-α and upregulating CD83, CD80, CD86 and CCR7. The HPC-mDC subsets also upregulate CD80 and CD83 upon TLR3, TLR4 or TLR7/8 ligation. Finally, both the ex vivo-generated pDCs and mDCs induced potent allogeneic T cell responses and activated CD8+ effector T cells against hematopoietic-restricted MiHA. These findings demonstrate that our SR1 culture system not only allows detailed study of DC differentiation and molecular regulations in vitro, but it also offers the opportunity to evaluate the in vivo efficacy of cultured DC subsets upon vaccination into patients with cancer and viral infections. Disclosures: Spanholtz: Glycostem Therapeutics: Employment.

scholarly journals Efficient In Vitro Expansion of Human Immunodeficiency Virus (HIV)-Specific T-Cell Responses by gag mRNA-Electroporated Dendritic Cells from Treated and Untreated HIV Type 1-Infected Individuals

2008 ◽  
Vol 82 (7) ◽  
pp. 3561-3573 ◽  
Author(s):  
Ellen R. Van Gulck ◽  
Guido Vanham ◽  
Leo Heyndrickx ◽  
Sandra Coppens ◽  
Katleen Vereecken ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
T Cell Responses ◽  
Cell Responses ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Developing an immunotherapy to keep human immunodeficiency virus type 1 (HIV-1) replication suppressed while discontinuing highly active antiretroviral therapy (HAART) is an important challenge. In the present work, we evaluated in vitro whether dendritic cells (DC) electroporated with gag mRNA can induce HIV-specific responses in T cells from chronically infected subjects. Monocyte-derived DC, from therapy-naïve and HAART-treated HIV-1-seropositive subjects, that were electroporated with consensus codon-optimized HxB2 gag mRNA efficiently expanded T cells, secreting gamma interferon (IFN-γ) and interleukin 2 (IL-2), as well as other cytokines and perforin, upon restimulation with a pool of overlapping Gag peptides. The functional expansion levels after 1 week of stimulation were comparable in T cells from HAART-treated and treatment-naïve patients and involved both CD4+ and CD8+ T cells, with evidence of bifunctionality in T cells. Epitope mapping of p24 showed that stimulated T cells had a broadened response toward previously nondescribed epitopes. DC, from HAART-treated subjects, that were electroporated with autologous proviral gag mRNA equally efficiently expanded HIV-specific T cells. Regulatory T cells did not prevent the induction of effector T cells in this system, whereas the blocking of PD-L1 slightly increased the induction of T-cell responses. This paper shows that DC, loaded with consensus or autologous gag mRNA, expand HIV-specific T-cell responses in vitro.

scholarly journals Primary stimulation by dendritic cells induces antiviral proliferative and cytotoxic T cell responses in vitro.

1989 ◽  
Vol 169 (4) ◽  
pp. 1255-1264 ◽  
Author(s):  
S E Macatonia ◽  
P M Taylor ◽  
S C Knight ◽  
B A Askonas
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
T Cell Responses ◽  
Class Ii ◽  
Cytotoxic T Cell ◽  
Hanging Drop ◽  
Cell Responses ◽  
Class Ii Mhc

We used well-gassed hanging drop (20 microliters) cultures with high concentrations of purified T cells from normal BALB/c mice to examine whether dendritic cells (DC) can induce primary antiviral proliferative T cell responses and generate virus-specific CTL. We found that DC exposed to infectious influenza virus in vitro or in vivo in small numbers (0.1-1%) resulted in strong proliferation of responder T cells within 3 d, and this was strongly inhibited by antibodies to class II MHC molecules. In addition, in 5-d cultures, the influenza-treated DC generated CTL specifically able to lyse influenza-infected syngeneic target cells bearing MHC class I antigens. The most potent nucleoprotein (NP) epitope recognized by BALB/c CTL is peptide 147-158 (Arg156-) and influenza-infected DC in vitro stimulated CTL recognizing this peptide, thus mimicking the response in mice primed by intranasal influenza infection. We also induced T cell proliferation and virus-specific CTL in cultures of normal T cells by stimulating with DC pulsed with the natural NP sequence 147-158 or the potent peptide 147-158 (Arg156-). Small numbers of peritoneal exudate cells, after activation with Con A to produce class II MHC expression and after removal of DC with a specific mAb (33DI), did not lead to primary CTL generation but initiated secondary stimulation in vitro. Our results using the hanging drop culture method and DC as APC have implications for studying the T cell repertoire for viral components in humans without the necessity of previous immunization.

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