CD2+/CD14+ monocytes rapidly differentiate into CD83+ dendritic cells

Since denditric cells (DC) represent the main players linking innate and adaptive immunity, their prompt generation from blood cells would be instrumental for an efficient immune response to infections. Consistent with this, CD2+ monocytes were found to express the DC maturation marker CD83, along with acquisition of high antigen-presenting activity, after a surprisingly short time in culture. This rapid process is associated with expression of IFN-alpha/beta genes and secretion of low levels of pro-inflammatory cytokines. Exposure of monocytes to IFN-alpha, but not to IL-4, induced persistence of CD2+/CD83+ cells, which were fully competent in stimulating primary responses by naive T cells. These results unravel the natural pathway by which infection-induced signals rapidly transform pre-armed monocytes into active DC.     

Engagement of CD33 surface molecules prevents the generation of dendritic cells from both monocytes and CD34+ myeloid precursors

Although CD33 represents an important marker of myeloid cell differentiation, its function remains poorly defined. In view of its homology with p75/AIRM1, a recently identified surface molecule which exerts a potent inhibition on NK cell function, we re-evaluated the effect of CD33 engagement in defined myeloid cell functions. Addition of anti-CD33 mAb to cultures of CD14+ monocytes supplemented with granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-4 and TNF-alpha, prevented the generation of dendritic cells. In these cultured cells, engagement of CD33 resulted in an increased surface binding of annexin-V, followed by cell death. Mature dendritic cells were resistant to the CD33-mediated effect. Also in CD34+ precursors, cultured in the presence of flt3-ligand, c-Kit-ligand, GM-CSF, IL-4 and TNF-alpha, addition of anti-CD33 mAb prevented the recovery of mature dendritic cells. These data suggest a regulatory role of CD33 in the myeloid cell maturation and may offer a tool to interfere with the monocyte/macrophage cell function as well as with the development of dendritic cells.     

Porphyromonas gingivalis lipopolysaccharides induce maturation of dendritic cells with CD14+CD16+ phenotype

Primary immune responses are initiated by dendritic cells (DC) that inform naive T helper cells about invading pathogens. DC undergo sequential events leading to irreversible maturation upon bacterial stimulation. To investigate the responses of DC during periodontal infection, we studied the effects of LPS from Porphyromonas gingivalis on DC. DC generated from human peripheral monocytes by culture with IL-4 and GM-CSF were incubated with P. gingivalis LPS (Pg LPS) or Escherichia coli LPS (Ec LPS). Flow cytometry and real-time quantitative RT-PCR analysis revealed that Pg LPS, but not Ec LPS, preferentially up-regulated CD14 and CD16 expression at protein and mRNA levels. Furthermore, Pg LPS preferentially induced the secretion of soluble CD14. CD1a, HLA-DR and CD54 were highly expressed on DC stimulated with both kinds of LPS; however, CD40, CD80, CD83 and CD86 expression on Pg LPS-stimulated DC was lower than on Ec LPS-stimulated DC. With regard to IL-6, IL-8, IL-10, IL-12 and RANTES production from DC and allogeneic T cell proliferation, Pg LPS was a weaker stimulator than Ec LPS. These results suggested that Pg LPS triggers maturation of DC with unique characteristics, which exhibited weak immunostimulatory activity and may contribute to induction of chronic inflammation at the site of periodontal infection.     

Mechanism of glucocorticoid-induced depletion of human CD14+CD16+ monocytes

Healthy donors infused with high doses of glucocorticoids [GCs; methyl-prednisolone (MP); 500 mg/day for 3 days] suffer a selective depletion of the CD14(+)CD16(+) monocytes such that these cells are reduced by 95% on day 5. In vitro studies revealed that at 11 h of culture in the presence of 10(-)(5) M MP, no depletion was observed as yet, but a reduction by 80% was seen after 24 h. In dose-response analysis, MP still led to a 50% reduction of CD14(+)CD16(+) monocytes at 10(-)(7) M. Depletion could not be overcome by addition of the cytokines interleukin-1beta or macrophage-colony stimulating factor, and it was independent of CD95. Depletion was, however, inhibited by the caspase 3,8 blocker z-Val-Ala-Asp, suggesting that cell death occurs in a caspase-dependent manner. Furthermore, blockade of depletion by RU-486 indicates that the intracellular GC receptor (GCR) is involved. Measurement of GCR by flow cytometry revealed a 50% higher level of expression in the CD14(+)CD16(+) monocytes. Our studies show a selective depletion of CD14(+)CD16(+) monocytes by GC treatment in vivo and in vitro, an effect to which the modestly increased level of GCR may contribute.     

TNF-alpha induces the generation of Langerin/(CD207)+ immature Langerhans-type dendritic cells from both CD14-CD1a and CD14+CD1a- precursors derived from CD34+ cord blood cells

CD34+ cell-derived hematopoietic precursors amplified with FLT3-ligand, thrombopoietin and stem cell factor became, after a 6-day induction with GM-CSF, IL-4 and TGF-beta1, HLA-DR+, CD1a+, CD83-, CD86-, CD80- cells. A fraction of them expressed Langerin, Lag, and E-cadherin, resembling epidermal Langerhans cells (LC). TNF-alpha added for the last 3 days only marginally induced CD83 expression, but strikingly increased the proportion of immature Langerin+CD83- LC. Langerin+CD83+ and Langerin+CD83- cells were functionally distinct, the former internalizing less efficiently Langerin than the latter. Both CD1a-CD14- and CD1a-CD14+ cells sorted from FLT3-ligand, thrombopoietin and stem cell factor cultures responded to TNF-alpha by an increase of Langerin+ cells. Thus, TNF-alpha rescued LC precursors irrespective of their commitment to the monocytic lineage. When added to GM-CSF, IL-4 and TGF-beta1 containing-cultures, LPS or IL-1beta also induced significant numbers of Langerin+CD83- immature cells displaying a low allostimulatory activity, while CD40-ligand largely promoted highly allostimulatory Langerin-CD83+ cells. Altogether, these data show that in contrast to CD40-ligand, which induced LC maturation even in presence of TGF-beta1, nonspecific proinflammatory factors such as TNF-alpha, IL-1 or LPS, essentially induced immature LC generation, and little cell activation in the presence of TGF-beta1.     

CD14~+CD16~+亚型单核细胞的研究进展

目前已经确定的外周血单核细胞有4种亚型,最主要的有2种,分别是CD14++CD16-和CD14+CD16+单核细胞。两种主要亚型的单核细胞在趋化因子受体、黏附分子的表达以及在迁移和分化特性上都是不同的。近年来发现CD14+CD16+细胞的促炎症细胞因子是高表达的,也是具有较高抗原提呈能力的细胞。本文对单核细胞的亚型,CD14+CD16+细胞的主要特性,以及这一群CD14+CD16+单核细胞对于人类相关的一些疾病的影响进行简要综述。     

Functional specializations of human epidermal Langerhans cells and CD14+ dermal dendritic cells

Little is known about the functional differences between the human skin myeloid dendritic cell (DC) subsets, epidermal CD207(+) Langerhans cells (LCs) and dermal CD14(+) DCs. We showed that CD14(+) DCs primed CD4(+) T cells into cells that induce naive B cells to switch isotype and become plasma cells. In contrast, LCs preferentially induced the differentiation of CD4(+) T cells secreting T helper 2 (Th2) cell cytokines and were efficient at priming and crosspriming naive CD8(+) T cells. A third DC population, CD14(-)CD207(-)CD1a(+) DC, which resides in the dermis, could activate CD8(+) T cells better than CD14(+) DCs but less efficiently than LCs. Thus, the human skin displays three DC subsets, two of which, i.e., CD14(+) DCs and LCs, display functional specializations, the preferential activation of humoral and cellular immunity, respectively.     

Thymosin-alpha1 modulates dendritic cell differentiation and functional maturation from human peripheral blood CD14+ monocytes

Although thymosins have been demonstrated to have immunomodulatory effects, it is still not clear whether they could affect dendritic cells (DCs), the most professional antigen-presenting cells. The objective of this study was to determine the effect and potential mechanisms of thymosin-alpha1 (Talpha1) on DC differentiation and functional maturation. Human peripheral blood CD14(+) monocytes were purified by using a magnetic separation column and cultured with GM-CSF and IL-4 to differentiate into immature DCs (iDCs). In the presence of Talpha1, iDC surface markers CD40, CD80, MHC class I and class II molecules were significantly upregulated as measured by flow cytemotry analysis. However, Tbeta4 or Tbeta10 did not show these effects on iDCs. There was an approximately 30% reduction in antigen (FITC-conjugated dextran)-uptake by Talpha1-treated iDCs as compared with non-Talpha1-treated iDCs. In addition, Talpha1-treated matured DCs (mDCs) showed an increased stimulation of allogeneic CD3(+) T-cell proliferation as measured by a mixed-lymphocyte reaction assay. Talpha1-treated mDCs also increased the production of several Th1- and Th2-type cytokines as measured by a Bio-Plex cytokine assay. Furthermore, rapid activation of p38 MAPK and NFkappaB was seen in Talpha1-treated iDCs as measured by a Bio-Plex phosphoprotein assay. Thus, Talpha1 significantly enhances DC differentiation, activation, and functions from human peripheral blood CD14(+) monocytes possibly through a mechanism of the activation of p38 MAPK and NFkappaB pathways. This study provides a basis to further evaluate Talpha1 as a possible adjuvant for a DC-directed vaccine or therapy.     

Heterogeneity of human blood monocytes: the CD14+CD16+ subpopulation

Previously, human blood monocyte subpopulations were defined by approaches that required their isolation, such as differential sedimentation or adherence. Therefore, enumeration of subpopulations and their analysis in disease remained difficult. Here, Löms Ziegler-Heitbrock suggests that expression of CD14 and CD16 can be used to define at least two subsets of monocytes with distinct functional properties.     

In vitro differentiation of porcine blood CD163- and CD163+ monocytes into functional dendritic cells

Swine monocytes constitute a heterogeneous cell population containing subsets with distinct functional capacities or representing different maturational stages. Based on the expression of CD163, we have recently identified two monocyte subpopulations. In this study, we investigate the ability of both CD163- and CD163+ monocytes to differentiate into dendritic cells (DCs) in the presence of GM-CSF and IL-4. Monocyte differentiation into DC is accompanied by an up-regulation of the expression of swine leukocyte antigen (SLA) I, SLA II and CD80/86 molecules, and a decrease in the expression of CD14, CD16 and CD163. These DC express the pan-myeloid marker SWC3 and display typical dendritic cytoplasmic projections. When monocytes are split into CD163+ and CD163- cells, both subsets give rise to DC. However, compared to CD163- monocyte-derived DC (MoDC), CD163+ MoDC appear to have reached a more advanced stage of maturation, expressing higher levels of SLA II and CD80/86 and inducing more efficiently proliferation of T cells to recall antigens and alloantigens.     

Expansion of CD14+CD16+ peripheral monocytes among patients with aseptic loosening

Objective and design  In this study, we have investigated the relevance of peripheral blood inflammatory CD14⁺CD16⁺ monocytes phenotype to patients with aseptic loosening (AL). Material and treatment  Immunophenotypes of monocytes were examined among patients with AL (n = 43), patients with mechanical loosening (ML, n = 30), patients with stable implant (SI, n = 16), and patients with osteoarthritis (OA, n = 17) using flow cytometry. Methods  Immunological assay was used to measure TNF-α and IL-1β levels in both sera and culture media of implant wear stimulated CD14⁺CD16⁺ and CD14⁺⁺CD16⁻ monocytes. Periprosthetic tissues were collected during surgery for histological assessment. Results  The frequency of CD14⁺CD16⁺ monocytes showed significant increase in AL patients than in ML, SI, and OA patients. A positive association was found between the subpopulation of CD14⁺CD16⁺ monocytes and plasma TNF-α and IL-1β level in AL patients. Furthermore, a positive correlation existed between the subpopulation of CD14⁺CD16⁺ monocytes and the total histopathology score. Conclusion  The results indicate that CD14⁺CD16⁺ monocytes represent a sensitive marker for the disease activity of AL, and may serve as an effective prognostic index to identify total joint replacement recipients who are at increased risk for osteolysis and progression of AL.     

CD4+/CD57+/CD69+ T lymphocytes and CD14+ dendritic cells accumulate in advanced follicular lymphoma

Follicular lymphoma is the second most frequent non-Hodgkin’s lymphoma, accounting for around 20 % of all lymphomas in Western countries. Initially, it behaves indolently, but in time becomes more aggressive and less susceptible to chemotherapy. Multiple features correlate with the survival of the patients and the progression of the disease, such as therapy with rituximab, tumour microenvironment and the intrafollicular proliferation index. Our research was focused on the association of specific components of tumour microenvironment and the tumour behaviour. The presence and the relative percentage of T lymphocytes, follicular dendritic cells, dendritic cells and macrophages was detected by immunohistochemical staining of the antigens specific for certain cell populations. Our results show that T lymphocytes and dendritic cells affect tumour growth, possibly through interactions with tumour cells. Higher patients’ ECOG score and the outcome of the disease are associated with the presence of CD14+ dendritic cells in tumour tissue, while the worse overall survival of patients is associated with the increased number of activated helper T lymphocytes that express marker of exhaustion CD57. Taken together, our results suggest that the efficiency of the immune response against follicular lymphoma depends on more than one type of immune cells. Also, we found that the phenotype of these cells, rather than just their number, affects the tumour behaviour and in consequence survival of the patients.     

Primary human alveolar epithelial cells can elicit the transendothelial migration of CD14+ monocytes and CD3+ lymphocytes

The ability of freshly isolated primary human alveolar epithelial cells (type II pneumocytes) to induce leucocyte migration across an endothelial monolayer was investigated. Three-way factorial analysis of variance (ANOVA) demonstrated that resting alveolar endothelial cells (AEC) could produce detectable quantities of monocyte chemoattractant protein 1 (MCP-1), which was upregulated in response to tumour necrosis factor-alpha (TNF-alpha) in a dose- and time-dependent fashion. Interferon-gamma (IFN-gamma) had no significant effect on this process. TNF-alpha and IFN-gamma both induced AEC to provoke migration of CD14+ monocytes and CD3+ lymphocytes across endothelium. IFN-gamma and TNF-alpha synergized in their ability to induce production of T lymphocyte, but not monocyte, chemoattractants from AEC. Leucocyte transendothelial migration was inhibited by anti-MCP-1 neutralizing antibody and by heparin, a polyanionic glycosaminoglycan (GAG). These data suggest that human AEC play a role in the multiple mechanisms that facilitate monocyte and T lymphocyte migration into the alveolar compartment of the lung under homeostasis and inflammatory conditions. One of these mechanisms is mediated via constitutive MCP-1 production by alveolar epithelial cells, which is upregulated by TNF-alpha.     

Decreased CD14+CCR2+ monocytes in active multiple sclerosis

The expression of CCR2, a receptor to MCP-1, on blood monocytes was measured in 15 patients with active multiple sclerosis (MS). We determined the ratio of CD4+CXCR3+cells (Th1), CD4+CCR4+cells (Th2), and CD14+CCR2+ cells using 3-color flow cytometry. The CD4+CXCR3+/CD4+CCR4+ ratio, which represents the Th1/Th2 balance, was significantly elevated in the active MS patients compared to the healthy controls. The expression of CCR2 and CD14 on the monocytes in the MS patients was markedly decreased. There was a significant negative correlation between the Th1/Th2 ratio and the CCR2 and CD14 expression on monocytes. In the pathogenesis of MS, the CD14+CCR2+ blood monocytes may play an important role in the shift from active MS to a state in which the disease is in remission.     

Density of CD163+ CD11c+ dendritic cells increases and CD103+ dendritic cells decreases in the coeliac lesion

Coeliac disease is a chronic inflammation of the intestinal mucosa controlled by gluten-specific T cells restricted by disease-associated HLA-DQ molecules. We have previously reported that mucosal CD11c(+) dendritic cells (DCs) are responsible for activation of gluten-reactive T cells within the coeliac lesion. In mice, intestinal CD11c(+) DCs comprise several functionally distinct subsets. Here, we report that HLA-DQ(+) antigen-presenting cells (APCs) in normal human duodenal mucosa can be divided into four subsets with striking similarities to those described in mice: CD163(+) CD11c(-) macrophages (74%), and CD11c(+) cells expressing either CD163 (7%), CD103 (11%) or CD1c (13%). CD103(+) and CD1c(+) DCs belonged to partly overlapping populations, whereas CD163(+) CD11c(+) APCs appeared to be a distinct population. In the coeliac lesion, we found increased density of CD163(+) CD11c(+) APCs, whereas the density of CD103(+) and CD1c(+) DCs was decreased, suggesting that distinct subpopulations of APCs in coeliac disease may exert different functions in the pathogenesis.     

Selective depletion of CD14+ CD16+ monocytes by glucocorticoid therapy

Glucocorticoids (GC) are potent anti-inflammatory and immunosuppressive agents that act on many cells of the body, including monocytes. Here we show that a 5-day course of high dose GC therapy differentially affected the CD14⁺⁺ and the CD14⁺ CD16⁺ monocyte subpopulations in 10 patients treated for multiple sclerosis. While the classical (CD14⁺⁺) monocytes exhibited a substantial increase from 495 ± 132 to 755 ± 337 cells/μl, the CD14⁺ CD16⁺ monocytes responded with a pronounced decrease from 36 ± 15 to 2 ± 3 cells/μl (P < 0.001). In 4/10 patients the CD14⁺ CD16⁺ monocytes fell below detection limits (< 0.2 cells/μl). This observation was confirmed when the CD14⁺ CD16⁺ monocytes were identified by virtue of their low CD33 expression as these cells decreased as well. After discontinuation of GC therapy the CD14⁺ CD16⁺ monocytes reappeared and reached normal levels after 1 week. The profound depletion of CD14⁺ CD16⁺ monocytes by GC as described here is a novel effect of GC action in vivo and may contribute to GC-mediated immunosuppression. Determination of the number of this monocyte subset may also serve to monitor the effectiveness of GC therapy in patients requiring immunosuppressive treatment.     

Notch signaling suppresses CD14+ monocytes cells activity in patients with chronic hepatitis C

Hepatitis C virus (HCV) infection always leads to chronic hepatitis via dysregulation of host immunity. Notch signaling also modulates the response of monocytes/macrophages. Thus, we aimed to investigate the regulatory role of Notch signaling to CD14⁺ monocytes. Forty patients with chronic hepatitis C and twenty normal controls (NC) were enrolled. CD14⁺ monocytes and CD4⁺ T cells were purified from peripheral bloods. Notch receptors' mRNA expression in CD14⁺ monocytes was semi‐quantified by real‐time PCR. Cytokine production by CD14⁺ monocytes in response to γ‐secretase inhibitor (GSI) was investigated by ELISA. GSI‐induced CD14⁺ monocytes activity to HCV clearance in Huh7.5 cells and to CD4⁺ T cell differentiation was also assessed in direct and indirect contact co‐culture system. Notch1 mRNA relative level was approximately 10‐fold elevated in CD14⁺ monocytes from chronic hepatitis C patients when compared with NC. GSI stimulation resulted in enhanced cytokines production by CD14⁺ monocytes from chronic hepatitis C patients. GSI‐stimulated CD14⁺ monocytes from chronic hepatitis C patients induced suppression of HCV RNA replication in both direct and indirect contact co‐culture system of CD14⁺ monocytes and HCVcc‐infected Huh7.5 cells, and this process was accompanied by elevation of interferon‐γ production but not increased target cell death. Moreover, GSI stimulation also enhanced CD14⁺ monocytes‐induced Th1 and Th17 cells activation, and this process required direct cell‐to‐cell contact. Effective antiviral therapy down‐regulated Notch1 mRNA expression and promoted cytokine production by CD14⁺ monocytes from chronic hepatitis C. Current data revealed an important immunoregulatory property of Notch signaling to CD14⁺ monocytes in chronic HCV infection.     

Differentiation of human monocytes into CD14 negative accessory cells: do dendritic cells derive from the monocytic lineage?

Human peripheral-blood monocytes, when cultured in the absence of serum, are prevented to differentiate to macrophages (M phi). Instead, they develop into accessory cells which by various properties resemble dendritic cells. Signals that control development either into M phi or monocyte-derived accessory cells (m-AC) have been investigated by us. By applying such triggers, m-AC phenotypes and functions approached those known from lymphoid dendritic cells. Only the monocyte marker CD14, which is absent from dendritic cells, remained positive on m-AC as a last indicator of the monocytic origin of the cells. We now report that this most stable marker of the monocyte/M phi lineage can completely be down-regulated by combining tissue culture techniques with the inductive property of interleukin-4. Evidence has also been obtained by us that the conversion of monocytes into both m-AC and M phi represents a true differentiation, as demonstrated by the expression of the nuclear marker lamin A/C.