Differentiation Of Human Dendritic Cells Research Articles

Leptin promotes differentiation and survival of human dendritic cells and licenses them for Th1 priming

Leptin promotes differentiation and survival of human dendritic cells and licenses them for Th1 priming

A cell line model for the differentiation of human dendritic cells

We have identified human monocytic (THP-1) and myelogenous CD34 + (KG-1) leukemia cell lines that can be differentiated rapidly into mature dendritic cells (DCs) when cultured in serum-free medium containing GM-CSF, TNF-α, and ionomycin. These hematopoietic cell line-derived DCs are highly pure and monotypic, and display the morphologic, phenotypic, molecular, and functional properties of DCs generated from human donor-derived monocytes or CD34 + hematopoietic progenitor cells. During differentiation into mature DCs, the cells exhibit de novo cell-surface expression of CD83, CD80, CD86, CD40, CD206, CD209, CD120a, CD120b, and intracellular synthesis of IL-10, increase their endocytotic capacity, and acquire characteristic stellate morphology. To further define the cells as DCs, cytosolic induction and upregulation of RelB and RelA (p65), transcription factors of the NF-κB/Rel family essential for differentiation and maturation of DCs, as well as upregulation of the immunoproteasome subunits LMP2, LMP7, and MECL-1, and the proteasome activator PA28α, components essential for efficient MHC class I peptide antigen processing, were demonstrated during differentiation of the cells. In contrast to the cell lines, the cell line-derived mature DCs are capable of stimulating allogeneic CD4 + and CD8 + T cells, ultimately defining them as potent antigen-presenting cells. The approach to differentiate THP-1 and KG-1 cells into immature and mature DCs may serve as an experimental model to study molecular events and pathways that govern the differentiation of human malignant myeloid precursors, monocytes, and CD34 + hematopoietic progenitor cells into DCs.

Leptin Promotes Differentiation and Survival of Human Dendritic Cells and Licenses Them for Th1 Priming

Leptin is an adipocyte-derived hormone/cytokine that links nutrition, metabolism, and immune homeostasis. Leptin is capable of modulating several immune responses. However, the effect of leptin on dendritic cells (DCs) has not yet been recognized. Because DCs are instrumental in the development of immune responses, in this study, we evaluated the impact of leptin on DC activation. We demonstrated the presence of leptin receptor in human immature and mature DCs both at mRNA and protein level and its capacity to transduce leptin signaling leading to STAT-3 phosphorylation. We found no consistent modulation of DC surface molecules known to be critical for their APC function in response to leptin. In contrast, we found that leptin induces rearrangement of actin microfilaments, leading to uropod and ruffle formation. At a functional level, leptin up-regulates the IL-1beta, IL-6, IL-12, TNF-alpha, and MIP-1alpha production. Coincident with this, leptin-treated DCs stimulate stronger heterologous T cell responses. Furthermore, we found that leptin down-regulates IL-10 production by DCs and drives naive T cell polarization toward Th1 phenotype. Finally, we found that leptin partly protects DCs from spontaneous and UVB-induced apoptosis. Consistent with the antiapoptotic effect of leptin, we observed the activation of NF-kappaB and a parallel up-regulation of bcl-2 and bcl-x(L) gene expression. These results provide new insights on the immunoregulatory function of leptin demonstrating its ability to improve DC functions and to promote DC survival. This is of relevance considering a potential application of leptin in immunotherapeutic approaches and its possible use as adjuvant in vaccination protocols.

Triptolide affects the differentiation, maturation and function of human dendritic cells

Triptolide is a purified component from a traditional Chinese herb Tripterygium wilfordii Hook F. It has been shown to have anti-inflammatory and immunosuppressive activities by its inhibitory effect on T cells. But the effect of triptolide on dendritic cells (DC) is unknown. Dexamethasone (Dex) is a classic immunosuppressive agent known to suppress the immune response at different levels and has recently found to modulate the development of DC, thereby influencing the initiation of the immune response. In this study, we investigated the affect of triptolide on the differentiation, maturation and function of DC differentiated from human monocytes (MoDC) in vitro in the presence of GM-CSF and IL-4. Dex was included in the study as a reference. Our data show that both triptolide and Dex prevented the differentiation in immature MoDC by inhibiting CD1a, CD40, CD80, CD86 and HLA-DR expression but upregulating CD14 expression, as well as by reducing the capacity of MoDC to stimulate lymphocyte proliferation in the allogeneic mixed lymphocyte reaction. They blocked the maturation of MoDC as totally blocked induction of CD83 expression and absent upregulation of CD40, CD80, CD86 and HLA-DR. In addition, higher concentration of triptolide (20 ng/ml) and 10 − 6 M Dex induced apoptosis in MoDC as measured by expression of APO2.7 and DNA fragmentation (TUNEL assay). However, the phagocytic capacity of MoDC was enhanced by triptolide but not Dex. Therefore, the suppression of DC differentiation, the function in immature DCs as well as the inhibition of DC maturation by triptolide may explain some of its immunosuppressive properties. It is suggested that DCs are a primary target of the immunosuppressive activity of triptolide.

Prostaglandin D2 affects the differentiation and functions of human dendritic cells: impact on the T cell response

The local environment in which dendritic cells (DC) differentiate is important for the acquisition of their immunostimulatory properties. Since prostaglandin D(2) (PGD(2)), a major prostanoid produced during inflammatory reactions, is involved in the control of immune responses, its effect on the differentiation and functions of human monocyte-derived dendritic cells (MDDC) was studied. We show that DC differentiated in the presence of PGD(2) (PG/DC) have an unusual phenotype, with modifications in the expression of molecules involved in antigen (Ag) capture and presentation, leading to higher endocytic and Ag-processing activities. However, under conditions that necessitated Ag processing and presentation, PG/DC have an impaired ability to stimulate naive T cells, whereas superAg-pulsed DC efficiently promote their proliferation. Upon lipopolysaccharide or TNF-alpha/IL-1beta stimulation, PG/DC phenotypically mature but produce abnormal amounts of immunoregulatory cytokines (decreased IL-12p70/IL-10 ratio). Moreover, mature PG/DC fail to up-regulate the chemokine receptor CCR7 and show an impaired migration towards its ligand CCL19. Finally, PG/DC favor the differentiation of naive T cells toward Th2 cells, an effect dependent on IL-10 and inducible costimulator ligand expression by DC. Most of the herein described effects of PGD(2) on MDDC can be reproduced, usually with a higher efficacy, with a selective D prostanoid receptor (DP)1, but not DP2, agonist. Taken as a whole, these results demonstrate that PGD(2) impacts DC differentiation and functions, and extend the concept that it exerts important roles in immunity.

Changes in the proteomic profile during differentiation and maturation of human monocyte-derived dendritic cells stimulated with granulocyte macrophage colony stimulating factor/interleukin-4 and lipopolysaccharide

Dendritic cells (DCs) are highly specialized antigen-presenting cells that play an essential role in the immune response. We used the proteomic approach based on two-dimensional gel electrophoresis and mass spectrometry to identify the protein changes that occur during differentiation of DCs from monocytes (Mo) stimulated with granulocyte macrophage colony stimulating factor/interleukin-4 (GM-CSF/IL-4) and during the maturation of immature DCs stimulated with lipopolysaccharide. Sixty-three differentially expressed proteins (+/- two-fold) were unambiguously identified with sequence coverage greater than 20%. They corresponded to only 36 different proteins, because 11 were present as 38 electrophoretic forms. Some proteins such as tropomyosin 4 and heat shock protein 71 presented differentially expressed electrophoretic forms, suggesting that many of the changes in protein expression that accompany differentiation and maturation of DCs occur in post-translationally modified proteins. The largest differences in expression were observed for actin (21-fold in Mo), Rho GDP-dissociation inhibitor 2 (20-fold in Mo), vimentin (eight-fold in immature DCs), lymphocyte-specific protein 1 (12-fold in mature DCs) and thioredoxin (14-fold in mature DCs). Several proteins are directly related to functional and morphological characteristics of DCs, such as cytoskeletal proteins (cytoskeleton rearrangement) and chaperones (antigen processing and presentation), but other proteins have not been assigned specific functions in DCs. Only a few proteins identified here were the same as those reported in proteomic studies of DCs, which used different stimuli to produce the cells (GM-CSF/IL-4 and tumor necrosis factor-alpha). These data suggest that the DC protein profile depends on the stimuli used for differentiation and especially for maturation.

Choosing a Dendritic Cell Profession

Circulating monocytes can differentiate into two types of professional antigen-presenting cells: macrophages or dendritic cells (DCs). However, the factors that determine which path they follow and that govern further differentiation remain incompletely understood. Bayry et al. found that DCs derived from monocytes (mo-DCs) of people with X-linked agammaglobulinemia (XLA), who have reduced numbers of circulating B cells and thus reduced amounts of circulating immunoglobulin, showed reduced expression of DC differentiation markers compared with mo-DCs from healthy donors. Stimulation with CD40 ligand or a monoclonal antibody against CD40 promoted XLA mo-DC maturation, as did exposure to physiological levels of immunoglobulin. Moreover, CD40-reactive natural antibodies (NAbs, which are produced without stimulation by foreign antigen and are often autoreactive) isolated from immunoglobulin promoted maturation of mo-DCs from both healthy donors and individuals with XLA. However, XLA mo-DCs differentiated with CD40-reactive NAbs secreted IL-10 (which limits inflammatory responses) and showed increased immunoreactivity for cAMP response element-binding protein 1 (CREB-1), whereas XLA mo-DCs stimulated with CD40 ligand secreted interleukin-12 (IL-12, which promotes inflammatory responses) and had increased immunoreactivity for NF-κB p65, NF-κB p50, and c-Rel. Thus, the authors propose that NAbs found circulating in immunoglobulin play a role in promoting the maturation of "bystander" mo-DCs, without directly promoting their ability to stimulate an immune response. J. Bayry, S. Lacroix-Desmazes, V. Donkova-Petrini, C. Carboneil, N. Misra, Y. Lepelletier, S. Delignat, S. Varambally, E. Oksenhendler, Y. Lévy, M. Debré, M. Kazatchkine, O. Hermine, S. V. Kaveri, Natural antibodies sustain differentiation and maturation of human dendritic cells. Proc. Natl. Acad. Sci. U.S.A. 101 , 14210-14215 (2004). [Abstract] [Full Text]

Effects of mesenchymal stem cells on differentiation, maturation, and function of human monocyte-derived dendritic cells.

Mesenchymal stem cells (MSCs) reportedly inhibit the mixed lymphocyte reaction. Whether this effect is mediated by dendritic cells (DCs) is still unknown. In this study, we used an in vitro model to observe the effects of MSCs and their supernatants on the development of monocyte-derived DCs. Phenotypes and the endocytosic ability of harvested DCs were determined by flow cytometry; interleukin 12 (IL-12) secreted by DCs was evaluated by enzyme-linked immunosorbent assay (ELISA); and the antigen-presenting function of DCs was evaluated by MLR. Our results show that MSCs inhibit the up-regulation of CD1a, CD40, CD80, CD86, and HLA-DR during DC differentiation and prevent an increase of CD40, CD86, and CD83 expression during DC maturation. MSCs supernatants had no effect on DCs differentiation, but they inhibited the up-regulation of CD83 during maturation. Both MSCs and their supernatants interfered with endocytosis of DCs, decreased their capacity to secret IL-12 and activate alloreactive T cells. Thus, effects of MSCs on DCs contribute to immunoregulation and development.

Mycophenolate mofetil inhibits differentiation, maturation and allostimulatory function of human monocyte-derived dendritic cells.

We have studied the effect of mycophenolate mofetil (MMF), a new drug used in prevention of transplant rejection, on differentiation, maturation and allostimulatory activity of human monocyte-derived dendritic cells (MDDC). MDDC were generated in vitro with granulocyte macrophage-colony stimulating factor (GM-CSF) and interleukin (IL)-4 in the presence or absence of MMF. MMF reduced the number of immature MDDC in culture, dose-dependently, by inducing apoptosis and inhibited their stimulatory activity on allogeneic lymphocytes. These changes correlated with down-regulation of co-stimulatory and adhesion molecules such as CD40, CD54, CD80 and CD86. No differences were observed in mannose receptor (MR)-mediated endocytosis, measured by the uptake of fluorescein isothiocyanate (FITC)-dextran. MDDC differentiated in the presence of MMF showed significantly reduced maturation upon stimulation with lipopolysaccharide, as judged by lower expresson of CD83 and co-stimulatory molecules, lower production of tumour necrosis factor (TNF)-alpha, IL-10, IL-12 and IL-18 as well as lower stimulation of alloreactive T cells including naive CD4+ CD45RA+ T cells. In contrast, MDDC matured in the presence of MMF showed a more marked decrease in the FITC-dextran uptake than mature MDDC cultivated without MMF and the phenomenon correlated with down-regulation of the MR expression. These results suggest that MMF impairs differentiation, maturation and function of human MDDC in vitro, which is an additional mechanism of its immunosuppressive effect.

Peritoneal dialysis solutions inhibit the differentiation and maturation of human monocyte-derived dendritic cells: effect of lactate and glucose-degradation products.

Peritoneal dialysis (PD) is a well-established therapy for end-stage renal failure, but its efficiency is limited by recurrent peritonitis. As PD solutions impair local inflammatory responses within the peritoneal cavity, we have analyzed their influence on the in vitro maturation of human monocyte-derived dendritic cells (MDDC). Evaluation of MDDC maturation parameters [expression of adhesion and costimulatory molecules, receptor-mediated endocytosis, allogeneic T cell activation, production of tumor necrosis factor alpha, interleukin (IL)-6 and IL-12 p70, and nuclear factor (NF)-kappaB activation] revealed that currently used PD solutions differentially inhibit the lipopolysaccharide (LPS)-induced maturation of MDDC, an inhibition that correlated with their ability to impair the LPS-stimulated NF-kappaB activation. Evaluation of PD components revealed that sodium lactate and glucose-degradation products impaired the acquisition of maturation parameters and NF-kappaB activation in a dose-dependent manner. Moreover, PD solutions impaired monocyte-MDDC differentiation, inhibiting the acquisition of DC markers such as CD1a and DC-specific intercellular adhesion molecule-3 grabbing nonintegrin (CD209). These findings have important implications for the initiation of immune responses under high lactate conditions, such as those occurring within tumor tissues or after macrophage activation.

Differentiation of human dendritic cells from monocytes in vitro using granulocyte-macrophage colony stimulating factor and low concentration of interleukin-4.

Several laboratories have developed culture systems that allow the generation of large numbers of human dendritic cells (DC) from monocytes using granulocyte-macrophage colony stimulating factor (GM-CSF), and interleukin-4 (IL-4). In this work we provided evidence that GM-CSF (100 ng/ml) in combination with a low concentration of IL-4 (5 ng/ml) was efficient in the generation of immature, non-adherent, monocyte-derived DC as the same concentration of GM-CSF, and ten times higher concentration of IL-4 (50 ng/ml). This conclusion was based on the similar phenotype profile of DC, such as the expression of CD1a, CD80, CD86, and HLA-DR, down-regulation of CD14, and the absence of CD83, as well as on their similar allostimulatory activity for T cells. A higher number of cells remained adherent in cultures with lower concentrations of IL-4 than in cultures with higher concentrations of the cytokine. However, most of these adherent cells down-regulated CD14 and stimulated the proliferation of alloreactive T cells. In contrast, adherent cells cultivated with GM-CSF alone were predominantly macrophages, as judged by the expression of CD14 and the inefficiency to stimulate alloreactive T cells. DC generated in the presence of lower concentrations of IL-4 had higher proapoptotic potential for the Jurkat cell line than DC differentiated with higher concentrations of IL-4, suggesting their stronger cytotoxic, anti-tumor effect.

Differentiation of human antigen-presenting dendritic cells from CD34+ hematopoietic stem cells in vitro.

Antigen-presenting dendritic cells (DCs) originate from hematopoietic stem cells in bone marrow through successive steps of differentiation (-). In peripheral tissues (e.g., skin), DCs are exposed to and capture antigens like viruses, bacteria, and other pathogens through endocytosis and phagocytosis. In the presence of maturation-inducing stimuli, such as inflammatory cytokines, DCs undergo a process of maturation and migrate via the lymphatic vessels to the secondary lymphoid organs. In the lymphoid tissue, they present the processed antigens to T cells in the context of major histocompatibility complex (MHC) class I and class II molecules and initiate potent antigen specific immune responses. Giving their unique properties as professional antigenpresenting cells, DCs are currently being assessed for medical therapy, such as immunotherapy of cancer (,).

Butyrate affects differentiation, maturation and function of human monocyte-derived dendritic cells and macrophages.

We studied the in vitro effects of butyric acid on differentiation, maturation and function of dendritic cells (DC) and macrophages (M(Phi)) generated from human monocytes. A non-toxic dose of butyrate was shown to alter the phenotypic differentiation process of DC as assessed by a persistence of CD14, and a decreased CD54, CD86 and HLA class II expression. The more immature differentiation stage of treated cells was confirmed further by their increased phagocytic capability, their altered capacity to produce IL-10 and IL-12, and their weak allostimulatory abilities. Butyrate also altered DC terminal maturation, regardless of the maturation inducer, as demonstrated by a strong down-regulation of CD83, a decreased expression of CD40, CD86 and HLA class II. Similarly, butyrate altered M(Phi) differentiation, down-regulating the expression of the restricted membrane antigens and reducing the phagocytic capacity of treated cells. To investigate further the mechanism by which butyrate hampers the monocyte dual differentiation pathway, we studied the effects of 1,25(OH)2D3 alone or in combination with butyrate on the phenotypic features of DC. Unlike 1,25(OH)2D3, butyrate inhibited DC -differentiation without redirecting it towards M(Phi). Combined treatment gave rise to a new cell subset (CD14(high), CD86 and HLA-DR(low)) phenotypically distinct from monocytes. These results reveal an alternative mechanism of inhibition of DC and M(Phi) differentiation. Altogether, our data demonstrate a novel immune suppression property of butyrate that may modulate both inflammatory and immune responses and support further the interest for butyrate and its derivatives as new immunotherapeutic agents.

Diltiazem impairs maturation and functions of human dendritic cells

The aim of this study was to define the effects of diltiazem, a calcium antagonist drug used in cardiology and in clinical transplantation, on the differentiation and maturation of human dendritic cells (DC). Herein, we demonstrate that diltiazem, in association with granulocyte macrophage–colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4), induces monocytes to differentiate into cells with many of the characteristic of DC. However, diltiazem-induced DC express high levels of mannose receptor and FcγRII and, consequently, manifest a higher endocytic activity compared with GM-CSF+IL-4-induced DC. Importantly, diltiazem-induced DCs have an impaired responsiveness to lipopolysaccharide and CD40 ligand because they produce decreased levels of IL-12 and reveal a reduced ability to stimulate alloreactive T-cell responses as well as in inducing interferon-γ producing Th1 cells. These effects may contribute to a decreased DC-dependent T-cell activation and may help to explain the immunoregulatory function of diltiazem and its effectiveness in preventing transplant rejection.

Polycyclic aromatic hydrocarbons affect functional differentiation and maturation of human monocyte-derived dendritic cells.

Polycyclic aromatic hydrocarbons (PAHs) such as benzo(a)pyrene (BP) are environmental carcinogens exhibiting potent immunosuppressive properties. To determine the cellular bases of this immunotoxicity, we have studied the effects of PAHs on differentiation, maturation, and function of monocyte-derived dendritic cells (DC). Exposure to BP during monocyte differentiation into DC upon the action of GM-CSF and IL-4 markedly inhibited the up-regulation of markers found in DC such as CD1a, CD80, and CD40, without altering cell viability. Besides BP, PAHs such as dimethylbenz(a)anthracene and benzanthracene also strongly altered CD1a levels. Moreover, DC generated in the presence of BP displayed decreased endocytic activity. Features of LPS-mediated maturation of DC, such as CD83 up-regulation and IL-12 secretion, were also impaired in response to BP treatment. BP-exposed DC poorly stimulated T cell proliferation in mixed leukocyte reactions compared with their untreated counterparts. In contrast to BP, the halogenated arylhydrocarbon 2,3,7,8-tetrachlorodibenzo-p-dioxin, which shares some features with PAHs, including interaction with the arylhydrocarbon receptor, failed to phenotypically alter differentiation of monocytes into DC, suggesting that binding to the arylhydrocarbon receptor cannot mimic PAH effects on DC. Overall, these data demonstrate that exposure to PAHs inhibits in vitro functional differentiation and maturation of blood monocyte-derived DC. Such an effect may contribute to the immunotoxicity of these environmental contaminants due to the major role that DC play as potent APC in the development of the immune response.

Inhibition of effects of endogenously synthesized histamine disturbs in vitro human dendritic cell differentiation

Histamine, a principal mediator in various physiological and pathological cell functions is synthesized from l-histidine exclusively by histidine decarboxylase, an enzyme, which is expressed in many tissues of mammalian organism. Histamine plays a role in various cellular functions, including cell differentiation. The aim of this study was to determine the presence and to characterize the role of the endogenously produced histamine during in vitro dendritic cell (DC) differentiation induced by interleukin-4 (IL-4) and granulocyte-monocyte colony stimulating factor (GM-CSF). The changes in intracellular histamine content, biosynthesis and gene expression of histidine decarboxylase were investigated during this process. One also studied how histamine receptor antagonists and a histamine synthesis blocker influence the expression of differentiation antigens on the DC during in vitro maturation. During in vitro differentiation parallel culture incubations were performed by adding H1 receptor antagonist triprolidine, H2 receptor antagonist tiotidine, the tamoxifene derivate DPPE which blocks the intracellular binding of histamine, and an irreversible blocker of histidine decarboxylase, α-fluoromethyl histamine (α-FMH). The results show simultaneous increase in both histidine decarboxylase level and histamine content during differentiation of elutriated monocytes toward DC. Both blockade of de novo histamine production (by α-FMH) and inhibition of histamine binding (by H1 and H2 receptor antagonists, triprolidine and tiotidine, respectively) markedly decreased CD40 expression and that of CD45 from the 3rd day of treatment. DPPE by disturbing intracellular interaction of histamine with cytochrome P-450 moieties was able to decrease the expression of CD45, CD86, HLA-DR, CD33, CD40 and CD11c. Based on the data it is suggested that endogenous histamine is actively synthesized during cytokine-induced in vitro DC differentiation. The functional relevance and autocrine and paracrine action of endogenously produced histamine is supported by the data showing that inhibition of histamine synthesis by HDC, blocking of histamine binding by both ‘extracellular’ histamine receptors (by specific antagonists, triprolidine and tiotidine) and ‘intracellular’ antagonists (DPPE) disturb the differentiation of DC. This conclusion is supported by the fact, that by the inhibition of histamine acting in an autocrine/paracrine way, the expression pattern of differentiation markers on DC is markedly changed.

The effect of calcineurin inhibitors and corticosteroids on the differentiation of human dendritic cells.

Corticosteroids and the calcineurin inhibitors cyclosporin A (CsA) and FK506 have been studied extensively regarding their effects on T lymphocytes, but their effects on dendritic cells (DC) are relatively unknown. Monocytes are one of the precursors of DC that differentiate into CD14-CD1a+ immature DC upon culture with IL-4 and GM-CSF. The presence of CsA or FK506 during differentiation did not affect DC development. In contrast, the presence of corticosteroids, either dexamethasone (Dex) or prednisolone (Pred), for as little as the first 48 h of culture blocked the generation of immature DC. Dex-DC were unresponsive to signals inducing maturation (CD40 ligand, lipopolysaccharide), as demonstrated by the absence of CD83, CD80/CD86 and HLA-DR up-regulation and their strongly reduced T cell stimulatory capacity. Furthermore, Dex-DC showed a decreased CD40 ligand-induced IL-6 and TNF-alpha production, a complete block in IL-12p40 production, while IL-10 production was unaffected. CsA-DC and FK506-DC showed a partial reduction in the production of TNF-alpha, whereas all other functional activities appeared to be similar to control DC. These data show that, when compared to calcineurin inhibitors, corticosteroids have a unique and profound inhibitory effect on the generation and function of DC.

Interferon-α and -β inhibit the in vitro differentiation of immunocompetent human dendritic cells from CD14+ precursors

Dendritic cell (DC) precursors and immature DC reside in epithelium where they encounter pathogens and cytokines, which stimulate their differentiation. We hypothesized that type-I interferons (IFN- and -β), cytokines that are produced early in the innate immune response against viruses and some bacteria, may influence DC differentiation and function. To examine this possibility, we used an in vitro model of DC differentiation in which initial culture of human CD14+monocytes with granulocyte–macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4 generates immature DC, and subsequent culture with tumor necrosis factor (TNF)- drives the final development into mature DC. We found in this model that IFN-/β, added from the initiation of the culture on, significantly reduced the survival and altered the morphology and differentiation of DC. TNF-–dependent maturation of IFN-β–treated immature DC led to cells with reduced expression of CD1a, CD40, CD54, and CD80 when compared with mature DC controls. IFN-/β–treated DC further had a reduced capacity to induce naive Th-cell proliferation through allostimulation or anti-CD3 monoclonal antibody stimulation. In addition, IFN-/β–treated DC secreted less IL-12 upon stimulation with Staphylococcus aureus Cowan strain or with CD4+ T cells, and this decrease correlated directly with their inability to support CD4+ T-cell secretion of IFN-γ, even though T-cell lymphotoxin production was unaffected. These findings indicate that type-I IFNs can influence the generation of acquired immune responses by modifying T-helper cell differentiation through the regulation of DC differentiation and function.

Interferon-α and -β inhibit the in vitro differentiation of immunocompetent human dendritic cells from CD14+ precursors

AbstractDendritic cell (DC) precursors and immature DC reside in epithelium where they encounter pathogens and cytokines, which stimulate their differentiation. We hypothesized that type-I interferons (IFN-α and -β), cytokines that are produced early in the innate immune response against viruses and some bacteria, may influence DC differentiation and function. To examine this possibility, we used an in vitro model of DC differentiation in which initial culture of human CD14+monocytes with granulocyte–macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4 generates immature DC, and subsequent culture with tumor necrosis factor (TNF)-α drives the final development into mature DC. We found in this model that IFN-α/β, added from the initiation of the culture on, significantly reduced the survival and altered the morphology and differentiation of DC. TNF-α–dependent maturation of IFN-β–treated immature DC led to cells with reduced expression of CD1a, CD40, CD54, and CD80 when compared with mature DC controls. IFN-α/β–treated DC further had a reduced capacity to induce naive Th-cell proliferation through allostimulation or anti-CD3 monoclonal antibody stimulation. In addition, IFN-α/β–treated DC secreted less IL-12 upon stimulation with Staphylococcus aureus Cowan strain or with CD4+ T cells, and this decrease correlated directly with their inability to support CD4+ T-cell secretion of IFN-γ, even though T-cell lymphotoxin production was unaffected. These findings indicate that type-I IFNs can influence the generation of acquired immune responses by modifying T-helper cell differentiation through the regulation of DC differentiation and function.

Nonsteroidal anti-estrogens inhibit the functional differentiation of human monocyte-derived dendritic cells

Dendritic cells (DC) are professional antigen-presenting cells with a unique capacity to initiate and regulate immune responses. Immature CD1a(+) DC can be cultured from CD14(+) monocytes in the presence of interleukin (IL)-4 and granulocyte macrophage colony-stimulating factor in vitro. Results of this study show that the nonsteroidal anti-estrogens toremifene and tamoxifen inhibit this differentiation. In the presence of anti-estrogens the cells lose CD14 expression, but remain CD1a(-) and clearly have less dendritic processes than immature DC. Functionally, anti-estrogen-treated cells are inferior to immature DC in inducing proliferation of allogeneic T cells and in producing IL-12 p70 protein after CD40 ligation. The expression of the costimulatory molecules CD80 and CD86 is differentially regulated by anti-estrogens during DC differentiation. Furthermore, anti-estrogens are also able to inhibit the terminal maturation of DC. By inhibiting the functional differentiation of DC, anti-estrogens may have a role in the treatment and prevention of autoimmune diseases. (Blood. 2000;95:2875-2882)