Capacity Of Monocyte-derived Dendritic Cells Research Articles

Abstract 1894: Immunophenotypic and functional characterization of higher-risk MDS patient moDCs

Abstract Background: Myelodysplastic syndromes (MDS) are the most common acquired cause of bone marrow failure. Baseline immunity among MDS patients varies significantly with limited ability to mount a clinically significant immune response, affecting treatment and survival outcomes. Dendritic cells (DCs) can be derived from the malignant MDS clones and have compromised immune function. Here we examine the immunophenotypes and endocytic capacity of monocyte-derived DCs (moDCs) from higher-risk MDS patients. Methods: Purified CD14+ cells were magnetically isolated from peripheral blood mononuclear cells from patients with IPSS-R Intermediate/High/Very High-risk MDS (collectively referred as higher-risk MDS) and age-matched healthy donors (n=8 and n=3, respectively). CD14+ cells were cultured in complete medium with IL-4 and GM-CSF for 6 days. Immature moDCs were then incubated with Ovalbumin-Alexa Fluor 488 conjugate (OVA), and cells from higher-risk MDS patients were also incubated with autologous tumor cell lines (TCLs) stained with a pH-sensitive red fluorescent dye (TCL-pHrodo). Phenotypic analysis was performed prior to transformation, pre- and post-incubation with OVA. Phenotypic parameters and endocytosis assays were measured by flow cytometry. Results: Comparing CD14-CD209+ immature moDCs from higher-risk MDS patients to healthy donors, there was no significant difference in CD86 (p=0.476) and CD80 expression (p=0.190), but significantly lower CCR7 expression (p=0.010). Higher-risk MDS moDCs post-incubation with OVA also had significantly lower CCR7 expression (p=0.013) compared to donor moDCs post-incubation. Uptake of OVA was comparable in higher-risk MDS and healthy donor immature moDCs (p=0.322). However, higher-risk MDS immature moDCs had significantly decreased internalization when incubated with TCL-pHrodo compared to OVA (p<0.001). TCL-pHrodo uptake varied significantly across patients (range 5-34%). When TCL-pHrodo uptake was correlated with marker expression, CD80, CD209, and CCR7 were largely uncorrelated (r<0.300), and CD86 was moderately correlated (r=0.579). Multiple correlation analysis found that two-marker combinations of CD80 with CD86 and CD86 with CCR7 correlated moderately well with TCL-pHrodo uptake (r=0.698 and r=0.592, respectively). Conclusions: Lower CCR7 expression among higher-risk MDS immature moDCs and post-incubation with OVA suggests dysfunction in the chemotactic ability of moDCs. Endocytic capacity of the autologous TCLs varies widely across MDS patients and is significantly lower than endocytic capacity for OVA, suggesting that DC and tumor micro-interactions are more complex than with an ovalbumin bead. Further studies, including whole exome and transcriptome sequencing of moDCs, may help elucidate mechanisms underlying differential endocytic capacity across MDS patients that could predict tumor sensitivity to immunotherapy. Citation Format: Randy G. Tsai, Hannah F. Fields, Xinlian Zhang, Valentina Ferrari, Soo J. Park, Rafael Bejar, Tiffany N. Tanaka. Immunophenotypic and functional characterization of higher-risk MDS patient moDCs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1894.

Lipid Antigen Presentation by CD1b and CD1d in Lysosomal Storage Disease Patients.

The lysosome has a key role in the presentation of lipid antigens by CD1 molecules. While defects in lipid antigen presentation and in invariant Natural Killer T (iNKT) cell response were detected in several mouse models of lysosomal storage diseases (LSD), the impact of lysosomal engorgement in human lipid antigen presentation is poorly characterized. Here, we analyzed the capacity of monocyte-derived dendritic cells (Mo-DCs) from Fabry, Gaucher, Niemann Pick type C and Mucopolysaccharidosis type VI disease patients to present exogenous antigens to lipid-specific T cells. The CD1b- and CD1d-restricted presentation of lipid antigens by Mo-DCs revealed an ability of LSD patients to induce CD1-restricted T cell responses within the control range. Similarly, freshly isolated monocytes from Fabry and Gaucher disease patients had a normal ability to present α-Galactosylceramide (α-GalCer) antigen by CD1d. Gaucher disease patients' monocytes had an increased capacity to present α-Gal-(1-2)-αGalCer, an antigen that needs internalization and processing to become antigenic. In summary, our results show that Fabry, Gaucher, Niemann Pick type C, and Mucopolysaccharidosis type VI disease patients do not present a decreased capacity to present CD1d-restricted lipid antigens. These observations are in contrast to what was observed in mouse models of LSD. The percentage of total iNKT cells in the peripheral blood of these patients is also similar to control individuals. In addition, we show that the presentation of exogenous lipids that directly bind CD1b, the human CD1 isoform with an intracellular trafficking to the lysosome, is normal in these patients.

Different immune response of dendritic cells of newborns of allergic and healthy mothers to bacterial stimuli.

Continuous increasing incidence of allergic diseases is calling for identifying early prognostic markers pointing to increased risk of allergy development and establishing protocols for preventive strategies limiting allergy development in predisposed individuals. It is important to better understand the critical events occurring in early postnatal life, especially the interaction of a newborn with microbial compounds important for the maturation of the neonatal immune system and setting immunoregulatory responses as well. Dendritic cells (DC) together with the cytokine microenvironment play an important role in priming of immune responses. The capacity of monocyte-derived DC (moDC) from cord blood of children of healthy and allergic mothers to respond to microbial antigens (Escherichia coli O86 (EcO86) and delipidated Bacillus firmus (DBF)) was tested by flow cytometry and quantitative real-time PCR. Both EcO86 and DBF were able to promote maturation of moDC, but moDC of children of allergic mothers expressed higher levels of activation markers CD80 and CD83. Increased gene expression of IL-6 and lower expression of indol-amine 2,3 dioxygenase were observed in moDC of neonates of allergic mothers, in comparison to healthy ones. A higher gene expression and an increased presence of activation markers on moDC of newborns of allergic mothers indicate a generally higher reactivity of these cells, possibly enabling easier development of inappropriate immune response after an allergen encounter.

1,25-Dihydroxyvitamin D3 modulates the phenotype and function of Monocyte derived dendritic cells in cattle

BackgroundThe active form of the vitamin D3, 1,25-Dihydroxyvitamin D3 (1,25-(OH)2D3) has been shown to have major effects not only on physiological processes but also on the regulation of the immune system of vertebrates. Dendritic cells are specialised antigen presenting cells which are in charge of the initiation of T-cell dependant immune responses and as such are key regulators of responses towards pathogens. In this study we set out to evaluate the effects of 1,25-(OH)2D3 on the phenotype of cattle monocyte-derived dendritic cells (MoDCs) and how the conditioning with this vitamin affects the function of these myeloid cells.ResultsMoDCs were generated from CD14+ monocytes with bovine IL-4 and GM-CSF with or without 1,25-(OH)2D3 supplementation for 10 days. Vitamin D conditioned MoDCs showed a reduced expression of co-stimulatory and antigen presenting molecules, as well as a reduced capability of endocytose ovalbumin. Furthermore, the capacity of MoDCs to induce proliferation in an allogeneic mixed leukocyte reaction was abolished when MoDCs were generated in presence of 1,25-(OH)2D3. LPS induced maturation of 1,25-(OH)2D3conditioned MoDCs resulted in lower secretion of IL-12 and higher IL-10 than that observed in MoDCs.ConclusionsThe typical immunotolerant phenotype observed in cattle DCs after exposure to 1,25-(OH)2D3 has a significant effect on the functionality of these immune cells, inhibiting the T-cell stimulatory capacity of MoDCs. This could have profound implications on how the bovine immune system deals with pathogens, particularly in diseases such as tuberculosis or paratuberculosis.

Effects of arsenic on porcine dendritic cells in vitro

Exposure to arsenic (As) is an ongoing, and in some places increasing, health problem. Still, however, the effects of As exposure on the immune system are not well understood. Dendritic cells (DC) are a critical immune cell that bridges the innate and adaptive immune systems. To determine the impact of inorganic (i)As exposure on DC, the effects of (geo)anthropogenically relevant levels of NaAsO2 on the function of porcine monocyte-derived DC (MoDC) were evaluated in an in vitro model. The results showed a low dose of iAs reduced the phagocytic capacity of MoDC. Furthermore, although surface expression of DC activation markers, such as major histocompatibility complex (MHC)-II, CD80/86, CD40 and CD25, were only slightly changed, MoDC T-cell proliferation-inducing capacity was remarkably diminished by iAs treatment. Additionally, iAs induced significant interleukin (IL)-6 secretion by MoDC after 12- or 24-h incubation, whereas IL-1β secretion was only significantly up-regulated after 12 h. The secretion patterns of IL-8, tumor necrosis factor α (TNFα and IL-10 by iAs-treated MoDC were almost similar to that by mock-treated MoDC. Considering the broad roles of DC in immunobiology, this finding deepens the understanding of molecular mechanisms/functional consequences underpinning the immunopathology, inflammation, and increases in infection arising from As exposure.

Monocyte-derived dendritic cells from cirrhotic patients retain similar capacity for maturation/activation and antigen presentation as those from healthy subjects

Few studies have investigated the impact of liver cirrhosis on dendritic cell function. The purpose of this study was to compare the activation and antigen-presentation capacity of monocyte-derived dendritic cells (MoDC) from cirrhotic patients (CIR) relative to healthy donors (HD). MoDC from CIR and HD were matured, phenotyped, irradiated and pulsed with 15mer peptides for two hepatocellular carcinoma-related antigens, alphafetoprotein and glypican-3, then co-cultured with autologous T-cells. Expanded T-cells were evaluated by interferon-gamma ELISPOT and intracellular staining. 15 CIR and 7 HD were studied. While CD14+ monocytes from CIR displayed enhanced M2 polarization, under MoDC-polarizing conditions, we identified no significant difference between HD and CIR in maturation-induced upregulation of co-stimulation markers. Furthermore, no significant differences were observed between CIR and HD in subsequent expansion of tumor antigen-specific IFNγ+ T-cells. Conclusion: MoDCs isolated from cirrhotic individuals retain similar capacity for in vitro activation, maturation and antigen-presentation as those from healthy donors.

Ivig Negatively Regulates LPS-Induced Monocytes Activation Through a Microrna-146a Related Mechanism

AbstractAbstract 3274 Background:Cells from the monocytic lineage are known to play a central role in the immune defense against pathogens. In the adaptive immune response, they act as antigen presenting cells to trigger T and B cell responses. Monocytic cells also participate in innate immunity following recognition of pathogen-associated molecular patterns (PAMPs) such as bacterial lipopolysaccharides (LPS), which leads to their activation and release of very potent inflammatory mediators. The innate immune response thus needs to be tightly regulated to control not only its onset, but also its termination in order to avoid excessive inflammation. Recent studies have shown that the differentiation and functions of monocytic cells involve small RNA species, named microRNAs (miRNAs). MiRNAs are 21–23 nucleotide long single strand RNAs, which mainly cause gene silencing by degradation of target mRNAs or by inhibition of translation. Among them, miR-146a has captivated interest as it plays an important role in the negative regulation of acute inflammatory responses during activation of the innate immune system. In fact, it has been shown that miR-146a expression is gradually increased in THP-1 monocytic cells following stimulation with LPS or cytokines (e.g. IL-1β and TNF-α) via a NF-κB dependent pathway. MiR-146a inhibits the expression of IRAK1 and TRAF6 leading to the subsequent suppression of NF-κB activity. Consequently, the expression of NF-κB target genes such as IL-1β, TNF-α and PU.1 is suppressed. Therefore, miR146a controls NF-κB signaling via a negative feedback regulation loop and thus can be considered as an anti-inflammatory mediator. IVIg is a therapeutic preparation of polyclonal human IgG isolated from the plasma of thousands of healthy donors. IVIg is well known for its anti-inflammatory effects on a variety of immune cells and processes. More precisely, it has been shown to abrogate the capacity of monocyte-derived dendritic cells to secrete pro-inflammatory cytokines while increasing the expression of anti-inflammatory cytokines such as IL-10. We thus hypothesize that at least some of the anti-inflammatory effects of IVIg on monocytic cells could be triggered through the modulation of miR-146a expression. Objectives:To evaluate the involvement of miR-146a in the anti-inflammatory effects of IVIg following LPS stimulation of human monocytes. Methods:Human monocytes were obtained from the blood of healthy volunteers and treated with LPS (1 mg/mL) or IVIg (15 mg/mL) alone or alternatively, pretreated with LPS followed by addition of IVIg. Pre-treatment with LPS was done during for 4 h prior to addition of IVIg for 3, 6, 12 and 24 hours. Cells were then recovered and separated in two parts. The first part was used to extract the small RNA fraction of total RNA for miRNA analysis and the second part was used for protein isolation. The miR-146a level was measured by real time PCR while NF-kB and IRF4 protein levels were evaluated by western blotting. Finally, the expression of the transcription factor PU.1 was evaluated by flow cytometry. Results:Our preliminary data revealed that addition of IVIg to LPS-pretreated human monocytes resulted in a significant upregulation of miR-146a expression associated with a significant reduction in NF-κB expression. Furthermore, the expression of the PU.1/IRF4 transcriptional activator complex involved in the stimulation of inflammatory cytokine production was modulated. Indeed, we found that the expression PU.1 was reduced in IVIg-treated cells whereas IRF4 expression was increased, thus promoting the IRF4-mediated cytokine production inhibitory pathway. Conclusion:Our preliminary data suggest that in human monocytes, the anti-inflammatory effects of IVIg may involve miR-146a negative feedback loop regulation of NF-κB activity. Disclosures:No relevant conflicts of interest to declare.

Inducible Heat Shock Protein 70 Reduces T Cell Responses and Stimulatory Capacity of Monocyte-derived Dendritic Cells

Heat shock protein 70 (Hsp70) has gained a lot of attention in the past decade due to its potential immunoregulatory functions. Some of the described proinflammatory functions of Hsp70 became controversial as they were based on recombinant Hsp70 proteins specimens, which were later shown to be endotoxin-contaminated. In this study we used low endotoxin inducible Hsp70 (also known as Hsp72, HSPA1A), and we observed that after a 24-h incubation of monocyte-derived immature dendritic cells (mo-iDCs) with 20 μg/ml of low endotoxin Hsp70, their ability to stimulate allogenic T cells was reduced. Interestingly, low endotoxin Hsp70 also significantly reduced T cell responses when they were simulated with either IL-2 or phytohemagglutinin, therefore showing that Hsp70 could alter T cell responses independently from its effect on mo-iDCs. We also reported a greater response of Hsp70 treatment when activated versus nonactivated T cells were used. This effect of Hsp70 was similar for all tested populations of T cells that included CD3(+), CD4(+), or CD8(+). Taken together, our observations strongly suggest that Hsp70 might dampen, rather than provoke, T cell-mediated inflammatory reactions in many clinical conditions where up-regulation of Hsp70 is observed.

Upregulation of Osteoactivin Upon Exposure to Tyrosine Kinase Inhibitors Impairs the T Cell Stimulatory Capacity of Monocyte-Derived Dendritic Cells

Abstract 1112▪▪This icon denotes a clinically relevant abstractTargeted therapies using tyrosine kinase (TK) inhibitors have significantly improved the treatment of cancer patients. Imatinib (Glivec, Gleevec, STI 571) was the first TK inhibitor (TKI) established for the treatment of cancer and efficiently blocks the activity of c-ABL, a non-receptor TK which is pathologically activated in philadelphia chromosome-positive (Ph+) chronic myelogenous leukemia (CML). Nilotinib (Tasigna) and dasatinib (Sprycel) are second-generation TKI that have shown efficacy in the treatment of Ph+ CML resistant or intolerant to imatinib. However, molecularly detectable disease persists in the majority of patients treated with TKI, causing relapse after discontinuation of TKI treatment in many cases. Thus, multiple approaches presently aim to combine TKI treatment with immunotherapy. As TKI, besides targeting their eponymous enzyme, influence multiple other signaling pathways involved in cellular functions, analysis of potential effects of TKI on immune effector cells may be key to develop successful combinatorial strategies. Due to their unique ability to initiate powerful anti-tumor T cell responses, dendritic cells (DC) are employed in many immunotherapeutic strategies aiming to eradicate the malignant cell population. Upon activation they change their expression pattern of cell surface molecules and secreted cytokines/chemokines, a process called DC maturation. Osteoactivin, also known as transmembrane glycoprotein NMB (GPNMB) and dendritic cell-associated transmembrane protein (DC-HIL), is a type I transmembrane glycoprotein that is detected abundantly in DC but not or substantially less in monocytes. Its expression can inhibit T cell activation by binding the type 1 transmembrane proteoglycan syndecan-4 (SD-4) on T cells. Here we extend our findings that the exposure of human peripheral blood monocytes to the immunosuppressive and anti-inflammatory cytokine IL-10 or to therapeutic concentrations of TKI during differentiation into monocyte-derived DC (moDC) leads to significant upregulation of osteoactivin at the transcript and protein level in vitro (Blood 2010 116: abstract 1733). We analyzed the expression of other inhibitory receptors, such as PD-L1, PD-L2, CD80, or CD86 and observed no significant differences of the expression under TKI treatment. Furthermore, we thoroughly examined the expression of osteoactivin in the presence of relevant maturation signals such as TLR ligands, IFN-γ or TNF. LPS, Poly I:C, Pam3Cys or R848 nearly abolished osteoactivin expression compared to untreated control cells. In contrast, IFN-γ or TNF did not significantly reduce osteoactivin expression below the basal level. To evaluate the involvement of osteoactivin in TKI-triggered effects on moDC function we performed mixed lymphocyte reactions with allogenic T cells. Osteoactivin upregulation upon exposure to imatinib, dasatinib and nilotinib resulted in significantly reduced T cell stimulatory capacity of moDC. This was not due to IL-10 upregulation but rather due to direct inhibitory effects of osteoactivin on T cell proliferation which could be overcome by addition of blocking anti-osteoactivin antibody. Our data demonstrate that upregulation of osteoactivin upon exposure of immature moDC to TKI is critically involved in the inhibition of DC function. These findings indicate that inhibition of osteoactivin expression or function may serve as a novel strategy in combinatory approaches using TKI and DC-based immunotherapy and may enhance the efficacy of immunotherapeutic interventions in cancer patients. Disclosures:No relevant conflicts of interest to declare.

Varying Effects of Different β-Glucans on the Maturation of Porcine Monocyte-Derived Dendritic Cells

β-Glucans are well known for their immunomodulatory capacities in humans and mice. For this reason, together with the European ban on growth-promoting antibiotics, β-glucans are intensively used in pig feed. However, as shown in the present study, there is much variation in the stimulatory capacities of β-glucans from different sources. Since dendritic cells (DCs) are the first cells that are encountered after an antigen is taken up by the intestinal epithelial cell barrier, we decided to investigate the effect of two concentrations (5 and 10 μg/ml) of five commercial β-glucan preparations, differing in structure and source, on porcine monocyte-derived dendritic cells (MoDCs). Although all β-glucans gave rise to a significant reduction of the phagocytic activity of DCs, only Macrogard induced a significant phenotypic maturation. In addition to Macrogard, zymosan, another β-glucan derived from Saccharomyces cerevisiae, and curdlan also significantly improved the T-cell-stimulatory capacity of MoDCs. Most interesting, however, is the cytokine secretion profile of curdlan-stimulated MoDCs, since only curdlan induced significant higher expression levels of interleukin-1β (IL-1β), IL-6, IL-10, and IL-12/IL-23p40. Since the cytokine profile of DCs influences the outcome of the ensuing immune response and thus may prove valuable in intestinal immunity, a careful choice is necessary when β-glucans are used as dietary supplement.

Impact of Psoralen/UVA-Treatment on Survival, Activation, and Immunostimulatory Capacity of Monocyte-Derived Dendritic Cells

Extracorporeal Photopheresis (ECP) has been shown to be an effective treatment of graft-versus-host disease, solid organ graft rejection, and other T-cell-mediated diseases. The mechanisms of action of ECP include lymphocyte apoptosis, cytokine modulation, and the induction of regulatory T cells. It has been suggested that dendritic cells (DCs) are more resistant to ECP-induced apoptosis and might be directly modulated by ECP. We tested this hypothesis using in vitro Psoralen/UVA (PUVA) treatment as an in vitro model of ECP. Monocyte-derived DCs (mo-DCs) were treated with 8-methoxypsoralen /UVA and analyzed for surface molecule expression, apoptosis markers, endocytosis, and migratory and immunostimulatory capacity. Mo-DC phenotype and cytokine secretion was tested after CD40L stimulation. Naive T cells stimulated with PUVA-treated mo-DCs were tested for Th1/Th2 cytokine secretion and associated chemokine receptor patterns. DCs underwent apoptosis after in vitro PUVA and in vivo ECP. In vitro, the induction of apoptosis was preceded by partial maturation of immature mo-DCs. PUVA-treated immature mo-DCs also exhibited enhanced migratory and immunostimulatory capacity. However, mo-DCs stimulation through CD40 ligation was abrogated and interleukin (IL)-12 secretion was abolished 24 hr after PUVA treatment. PUVA-treated mo-DCs skewed naive T cells toward a Th2 response as defined by increased IL-4, IL-10, and IL-13 and decreased interferon-gamma levels, and the expression of the Th2-associated chemokine receptors CCR4 and CCR10. The observed Th2 shift was partially reversed by exogenous IL-12. These data suggest that direct modulation of DC function as well as apoptosis contribute to the immunoregulatory effects of ECP.

Monocyte chemoattractant protein-1 selectively inhibits the acquisition of CD40 ligand-dependent IL-12-producing capacity of monocyte-derived dendritic cells and modulates Th1 immune response.

Accumulating evidence indicates that monocyte chemoattractant protein-1 (MCP-1), a CC chemokine, also displays immunoregulatory functions and may be involved in Th subset differentiation. In this study, we examined the effects of MCP-1 on the cytokine-driven differentiation of monocytes into dendritic cells (DCs), the most potent APCs for naive T cells. We found that DCs generated in the presence of MCP-1 displayed a markedly reduced production of IL-12 in response to CD40 ligand but not in response to Staphylococcus aureus stimulation in the presence or absence of IFN-gamma. The production of IL-10, a potent endogenous IL-12 inhibitor, was not affected by MCP-1. Whereas the inhibitory activity of MCP-1 on IL-12 production by monocytes was sensitive to pertussis toxin, its effects on DC differentiation were pertussis toxin resistant. MCP-1 did not affect the surface phenotype and T cell-stimulating activity of DCs, but most interestingly, naive T cells stimulated with MCP-1-primed DCs produced much less IFN-gamma but the same levels of IL-13. Taken together, our results indicated that MCP-1 modulates the differentiation of monocytes into DCs and may thereby inhibit Th1 cell development.

Cimetidine modulates the antigen presenting capacity of dendritic cells from colorectal cancer patients.

Cimetidine, a H2 receptor antagonist, has been reported to improve survival in gastrointestinal cancer patients. These effects have largely been attributed to the enhancing effects of cimetidine on the host's antitumour cell-mediated immune response, such as inhibition of suppressor T lymphocyte activity, stimulation of natural killer cell activity and increase of interleukin-2 production from helper T lymphocytes. We conducted an in vitro study on the effects of cimetidine on differentiation and antigen presenting capacity of monocyte-derived dendritic cells from advanced colorectal cancer patients and normal controls. As a result, an investigation of expression of surface molecules associated with dendritic cells by flow cytometric analyses showed that cimetidine had no enhancing effect on differentiation of dendritic cells from cancer patients and normal controls. An investigation of [3H]thymidine incorporation by allogeneic mixed lymphocyte reactions revealed that cimetidine increased the antigen presenting capacity of dendritic cells from both materials. Moreover, a higher antigen presenting capacity was observed in advanced cancer patients compared to normal controls. These effects might be mediated via specific action of cimetidine and not via H2 receptors because famotidine did not show similar effects. Our results suggest that cimetidine may enhance the host's antitumour cell-mediated immunity by improving the suppressed dendritic cells function of advanced cancer patients.British Journal of Cancer (2002) 86, 1257–1261. DOI: 10.1038/sj/bjc/6600233 www.bjcancer.com© 2002 Cancer Research UK

Interferon-β increases the stimulatory capacity of monocyte-derived dendritic cells to induce IL-13, IL-5 and IL-10 in autologous T-cells

Dendritic cells (DCs) are key regulators of immune responses and have been associated with autoimmunity in animal models and human disease. The effects of interferon beta (IFN-β), an immunomodulatory cytokine used in multiple sclerosis (MS) therapy, on DCs are not well understood. Monocyte-derived DCs at different stages of maturation were stimulated with IFN-β and DC-phenotype and stimulatory function were measured. IFN-β inhibited the development of DCs at early stages but enhanced DC maturation. Moreover, IFN-β enhanced the capacity of DCs to stimulate autologous T-cells to secrete IL-13, IL-10 and IL-5. Thus, IFN-β has both immunostimulatory and immunosuppressive effects on DCs depending on the stage of maturation.