Dendritic cell precursor populations of mouse blood: identification of the murine homologues of human blood plasmacytoid pre-DC2 and CD11c+ DC1 precursors.
(9/629)
Immature and predendritic cells (pre-DCs) of human blood are the most readily accessible human DC sources available for study ex vivo. Murine homologues of human blood DCs have not been described. We report the isolation and characterization of 2 populations of precursor DCs in mouse blood. Mouse blood cells with the surface phenotype CD11c(lo)CD11b(-)CD45RA(hi) closely resemble human plasmacytoid cells (or pre-DC2) by morphology and function. On stimulation with oligonucleotides containing CpG motifs (CpG), these cells make large amounts of type 1 interferons and rapidly develop into DCs that bear CD8, though they may be distinct from the CD8(+) DCs in the unstimulated mouse. A second population of cells with the surface phenotype CD11c(+)CD11b(+)CD45RA(-) closely resembles the immediate precursors of pre-DC1, rapidly transforming into CD8(-) DCs after tumor necrosis factor-alpha (TNF-alpha) stimulation. These findings indicate the close relationship between human and mouse DCs, provided cells are obtained directly from equivalent source materials. (+info)
Granulocyte-colony stimulating factor increases CD123hi blood dendritic cells with altered CD62L and CCR7 expression.
(10/629)
Changes in blood dendritic cell (BDC) counts (CD123(hi)BDC and CD11c(+)BDC) and expression of CD62L, CCR7, and CD49d were analyzed in healthy donors, multiple myeloma (MM), and non-Hodgkin lymphoma (NHL) patients, who received granulocyte-colony stimulating factor (G-CSF) containing peripheral blood stem cell (PBSC) mobilization protocols. Low-dose G-CSF in healthy donors (8-10 microg/kg/d subcutaneously) and high-dose G-CSF in patients (30 microg/kg/d) increased CD123(hi)BDC (2- to 22-fold, mean 3.7 x 10(6)/L-17.7 x 10(6)/L and 1.9 x 10(6)/L-12.0 x 10(6)/L) in healthy donors and MM but decreased CD11c(+)BDC (2- to 10-fold, mean 5.7 x 10(6)/L-1.6 x 10(6)/L) in NHL patients, on the day of apheresis, compared with steady state. After apheresis, CD123(hi)BDC counts remained high, whereas low CD11c(+)BDC counts tended to recover in the following 2-5 days. Down-regulation of CD62L and up-regulation of CCR7 on CD123(hi)BDC were found in most healthy donors and MM patients. CD49d expression was unchanged. Thus, PBSC mobilization may change BDC counts by altering molecules necessary for BDC homing from blood into tissues. (+info)
Processing and degradation of exogenous prion protein by CD11c(+) myeloid dendritic cells in vitro.
(11/629)
The immune system plays an important role in facilitating the spread of prion infections from the periphery to the central nervous system. CD11c(+) myeloid dendritic cells (DC) could, due to their subepithelial location and their migratory capacity, be early targets for prion infection and contribute to the spread of infection. In order to analyze mechanisms by which these cells may affect prion propagation, we studied in vitro the effect of exposing such DC to scrapie-infected GT1-1 cells, which produce the scrapie prion protein PrP(Sc). In this system, the DC efficiently engulfed the infected GT1-1 cells. Unexpectedly, PrP(Sc), which is generally resistant to protease digestion, was processed and rapidly degraded. Based on this observation we speculate that CD11c(+) DC may play a dual role in prion infections: on one hand they may facilitate neuroinvasion by transfer of the infectious agent as suggested from in vivo studies, but on the other hand they may protect against the infection by causing an efficient degradation of PrP(Sc). Thus, the migrating and highly proteolytic CD11c(+) myeloid DC may affect the balance between propagation and clearance of PrP(Sc) in the organism. (+info)
Endothelial determinants of dendritic cell adhesion and migration: new implications for vascular diseases.
(12/629)
OBJECTIVE: Atherosclerosis is a chronic disease triggered by endothelial injury and sustained by inflammation. Dendritic cells (DCs) are critical for the cell-mediated arm of an immune response and are known to influence inflammatory immunity. A fundamental aspect of DC function is their capacity to adhere and migrate through vascular endothelial cells (ECs). We investigated the role of endothelial activation and dysregulation of the NO pathway on DC adhesion and migration. METHODS AND RESULTS: We discovered that DC adhesion and migration are modulated by changes in endothelial function. DC adhesion and transmigration were markedly increased after exposing ECs to hypoxia, oxidized low density lipoprotein, or tumor necrosis factor-alpha. Specifically, inhibition of endothelial NO synthase increased DC binding and transmigration. L-Arginine or 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibition partially decreased DC-EC interaction. CONCLUSIONS: The results of this study suggest that the adhesion and migration of DCs are increased by stimuli known to accelerate atherogenesis. Vice versa, augmentation of endothelial NO synthase activity prevents DC adhesion. These findings may provide insight into the inflammatory processes occurring in atherosclerosis. Because DCs control immunity, regulating DC-EC interaction may be relevant to inflammation and atherogenesis. (+info)
Adenovirus vector-mediated overexpression of a truncated form of the p65 nuclear factor kappa B cDNA in dendritic cells enhances their function resulting in immune-mediated suppression of preexisting murine tumors.
(13/629)
PURPOSE: The purpose of this study was to evaluate the effect of the Rel homology domain (RHD) of the transcription factor, nuclear factor kappa B (NF kappa B), on proinflammatory gene expression in bone marrow-derived dendritic cells (BMDCs). EXPERIMENTAL DESIGN: We used an adenovirus vector encoding only the RHD of the NF kappa B (p65 family member) cDNA (AdRHD) to transduce murine BMDCs ex vivo. Endpoints measured included BMDC expression of activation markers, cytokine secretion, peptide antigen presentation, and the ability of these transduced cells to induce antitumor immunity in vivo. RESULTS: AdRHD-transduced BMDCs secreted higher levels of the cytokines interleukin (IL) 1 beta, IL-6, and IL-12 (p40) compared with sham-transduced BMDCs or those transduced with an empty vector. AdRHD induced heightened surface expression of the activation markers CD40, B7.1, B7.2, and MHC class II on BMDCs, and these cells were able to present a peptide antigen to a T-lymphocyte hybridoma more efficiently than controls in vitro. Growth of syngeneic, established tumors (CT26 and B16.F10) was inhibited, and survival was prolonged in the mice that received intratumoral AdRHD-modified BMDCs compared with controls. Splenocytes from CT26 tumor-bearing animals that received intratumoral AdRHD-modified BMDCs were able to lyse CT26 target cells more efficiently than controls. Similar experiments using host mice harboring targeted mutations in CD4 and CD8, as well as BMDCs from mice lacking MHC class I, MHC class II, or IL-12 revealed that this tumor immunity was dependent on the presence of CD4+ and CD8+ cells in the tumor-bearing host, as well as MHC class I, MHC class II, and IL-12 expression by the administered BMDCs. Furthermore, induction of IL-12 (p40) expression by AdRHD was completely abrogated in BMDCs lacking the c-Rel NF kappa B family member. CONCLUSIONS: We made the following conclusions: (a) gene transfer-mediated overexpression of the RHD of NF kappa B activates BMDCs; (b) AdRHD-transduced BMDCs induce antitumor immunity when administered intratumorally, an effect mediated by both the CD4+ T cell/MHC class II and the CD8+ T cell/MHC class I pathways, as well as IL-12; and (c) IL-12 (p40) up-regulation by the RHD transgene in BMDCs is dependent on the presence of the c-Rel NF kappa B family member. (+info)
Secretion of interleukin-10 or interleukin-12 by LPS-activated dendritic cells is critically dependent on time of stimulus relative to initiation of purified DC culture.
(14/629)
Dendritic cells (DC) are key regulators of adaptive immunity with the potential to induce T cell activation/immunity or T cell suppression/tolerance. DC are themselves induced by "maturation" signals such as bacterial lipopolysaccharide (LPS). We demonstrate here that LPS can stimulate DC to display similar maturation phenotypes but to differentiate toward an interleukin (IL)-10(high)- or IL-12(high)-secretor profile depending on the timing of maturation signal induction. Immediate/early administration of LPS induced purified bone marrow-derived DC (BMDC) to differentiate as IL-10(high)IL-12(low)-secreting cells, termed early DC (eDC). Conversely, delayed administration of LPS altered the DC cytokine profile to IL-10(low)IL-12(high), termed later DC (lDC). The presence of IL-4 enhanced the yield and maturation of BMDC but inhibited LPS-induced IL-10 production by eDC. In contrast, interferon-gamma reduced the yield of DC but promoted the level of LPS-induced IL-10 production by lDC. Our data provide new evidence that ex vivo manipulation and the cytokine environment regulate DC maturation status and cytokine-secretor phenotype with implications for the control of T cell differentiation and function via DC-based immunotherapeutic strategies. (+info)
Differential effects of G-CSF mobilisation on dendritic cell subsets in normal allogeneic donors and patients undergoing autologous transplantation.
(15/629)
It has been suggested that the immunological properties of cytokine primed PBSC may reflect the presence of altered levels of cellular components. In this study the changes induced in blood dendritic cell (DC) subsets following G-CSF mobilisation are analysed. Analysis of normal donors (n = 64) demonstrated considerable individual variation in the absolute numbers (x10(6)/l) of resting blood CD11c(-) DC (1.2-26.2) and CD11c(+) DC (0.9-34.7) as well as in the CD11c(-)/CD11c(+) DC ratio (0.29-4.13). G-CSF therapy increased CD11c(-) DC numbers to above the normal range in all normal donors analysed (n = 6) and the CD11c(-)/CD11c(+) ratio was also increased to >2.0 in all donors. Patients undergoing autologous PBSCT showed a heterogeneous response to mobilisation and although total DC and CD11c(-) DC numbers were increased in the majority (8/14), they remained within the normal range post mobilisation. The CD11c(-)/CD11c(+) ratio decreased in 5/15 patients and only three patients had ratios >2.0 post mobilisation. Post G-CSF the DC from all normal donors and 13/14 patients had an immature phenotype. These results demonstrate that G-CSF mobilisation induces relatively consistent changes in the number and ratio of DC subsets in normal donors, but considerable variation is seen in the response of patients undergoing mobilisation for autologous PBSCT. (+info)
Murine plasmacytoid pre-dendritic cells generated from Flt3 ligand-supplemented bone marrow cultures are immature APCs.
(16/629)
The putative counterparts of human plasmacytoid pre-dendritic cells (pDCs) have been described in vivo in mouse models and very recently in an in vitro culture system. In this study, we report that large numbers of bone marrow-derived murine CD11c(+)B220(+) pDCs can be generated with Flt3 ligand (FL) as the sole exogenous differentiation/growth factor and that pDC generation is regulated in vivo by FL because FL-deficient mice showed a major reduction in splenic pDC numbers. We extensively analyzed bone marrow-derived CD11c(+)B220(+) pDCs and described their immature APC phenotype based on MHC class II, activation markers, and chemokine receptor level of expression. CD11c(+)B220(+) pDCs showed a nonoverlapping Toll-like receptor pattern of expression distinct from that of classical CD11c(+)B220(-) dendritic cells and were poor T cell stimulators. Stimulation of CD11c(+)B220(+) pDCs with oligodeoxynucleotides containing certain CpG motifs plus CD40 ligand plus GM-CSF led to increased MHC class II, CD80, CD86, and CD8alpha expression levels, to a switch in chemokine receptor expression that affected their migration, to IFN-alpha and IL-12 secretion, and to the acquisition of priming capacities for both CD4(+) and CD8(+) OVA-specific TCR-transgenic naive T cells. Thus, the in vitro generation of murine pDCs may serve as a useful tool to further investigate pDC biology as well as the potential role of these cells in viral immunity and other settings. (+info)