PPD extract induces the maturation of human monocyte-derived dendritic cells

Dendritic cells (DCs) are the most powerful antigen presenting cells, capable of inducing T-dependent immune responses even in naive T cells. DCs are of special interest as cellular adjuvants for immunity induction in clinical settings and several methods for their generation and maturation are recently under investigation. The present study was set out to define the effects of PPD (Purified Protein Derivative), a mycobacterial extract used in the tuberculin skin test, on in vitro differentiation and maturation of human monocyte derived dendritic cells. Immature DCs were prepared from the peripheral blood monocytes of healthy volunteers by culturing in a medium supplemented with granulocyte macrophage colony stimulating factor (GM-CSF) and interleukin-4 (IL-4). The resultant cells were then stimulated with PPD extract and their properties such as cell morphology and the expression of key surface molecules were compared with tumor necrosis factor-alpha (TNF-alpha) stimulated immature DCs. Our results suggest that mycobacterial purified extract is as potent as TNF-alpha, a well-established DC stimulator, in induction of maturation in human monocyte derived DCs. We also ruled out the contribution of lipopolysaccharide (LPS) and beta-glucan contamination in maturation effect of PPD preparations. So, PPD as an examined safe material for in vivo consumption could be used to stimulate DC maturation in DC based immunotherapy protocols.     

Distinct effect of CD40 and TNF-signaling on the chemokine/chemokine receptor expression and function of the human monocyte-derived dendritic cells

A key and limiting step in the process of human monocyte-derived dendritic cells （mDCs） for clinical use is their in vitro maturation and in vivo migration. We previously observed that CD40 signal facilitated human mDC growth and maturation. To further explore this process, mDCs generated with GM-CSF and IL-4 were co-cultured with apoptotic tumor cells for 24 hours, followed by incubating with anti-CD40 monoclonal antibody or TNF-a for 48 hours to generate mature DCs. The chemokine/chemokine receptor expression and functions of mature DCs upon various stimuli were determined. The expression of costimulatory molecules on apoptotic tumor cell-loaded mature DCs co-cultured with either anti-CD40 antibody （anti-CD40-DCs） or TNF-a （TNF-DCs） were up-regulated compared to immature DCs, consistent with the abilities of these cytokine to drive DC maturation in vitro. The mRNA levels of chemokines such as stromal cell-derived factor-1a （SDF-1a）, EBV-induced molecule 1 ligand chemokine （ELC）, and IFN inducible protein-10 （IP-10） in anti-CD40 activated DCs were increased and the dendritic cell-specific chemokine 1 （DC-CK1） was moderately up-regulated as compared with other mature DCs. The corresponding chemokine receptors CXCR4 and CCR7 of anti-CD40-DCs were significantly expressed. The CXCR3 expression on activated T cells stimulated by anti-CD40-DCs was also increased. Moreover, the anti-CD40-DCs had a stronger ability to stimulate T cell proliferation than any other DCs. The NF-xB activity was much higher in anti-CD40-DCs than that of TNF-DCs. These results offer further evidence of the importance of the CD40 signal in developing efficient human DC vaccines for cancer immune therapy. Cellular ＆ Molecular Immunology.     

CNL, a ricin B-like lectin from mushroom Clitocybe nebularis, induces maturation and activation of dendritic cells via the toll-like receptor 4 pathway

A novel lectin, isolated from the basidiomycete mushroom Clitocybe nebularis and termed C. nebularis lectin (CNL), exhibits an immunostimulatory effect on the most potent antigen‐presenting cells, the dendritic cells (DCs). Treatment of human monocyte‐derived DCs with CNL in doses from 1 to 10 μg/ml resulted in a dose‐dependent induction of overall DC maturation characteristics. Exposure of DCs to CNL for 48 hr resulted in extensive up‐regulation of co‐stimulatory molecules CD80 and CD86, as well as of the maturation marker CD83 and HLA‐DR molecules. Such CNL‐matured DCs (CNL‐DCs) were capable of inducing a T helper type 1‐polarized response in naive CD4⁺ CD45RA⁺ T cells in 5‐day allogeneic co‐cultures. The allostimulatory potential of CNL‐DCs was significantly increased relative to untreated controls, as was their capacity to produce several pro‐inflammatory cytokines such as interleukin‐6, interleukin‐8 and tumour necrosis factor‐α. By using a specific Toll‐like receptor 4 (TLR4) signalling inhibitor, CLI‐095, as well as Myd88 inhibitory peptide, we have shown that DC activation by CNL is completely dependent on the TLR4 activation pathway. Furthermore, activation of TLR4 by CNL was confirmed via TLR4 reporter assay. Measurement of p65 nuclear factor‐κB and p38 mitogen‐activated protein kinase (MAPK) phosphorylation levels following CNL stimulation of DCs revealed primarily an increase in nuclear factor‐κB activity, with less effect on the induction of p38 MAPK signalling than of lipopolysaccharide‐matured DCs. The CNL had the ability to activate human DCs in such a way as to subsequently direct T helper type 1 T‐cell responses. Our results encourage the use of mushroom‐derived lectins for use in therapeutic strategies with aims such as to strengthen anti‐tumour immune responses.     

Heat-inactivated Lactobacillus rhamnosus and Lactobacillus delbrueckii induce efficient maturation and differential cytokine production in human monocyte derived dendritic cells

Probiotics' strain specific immunoregulatory properties in development of protective immune outcomes are believed to be induced by targeting and polarising dendritic cells (DCs) as the key determinants of the immune response. Therefore, we studied the effects of a heat-inactivated form of Lactobacillus rhamnosus GG (LGG) and Lactobacillus delbrueckii (L.del) on maturation pattern and extracellular cytokine production profile of monocyte derived dendritic cells. Expression of specific maturation markers and induction of extracellular cytokines were detected by flow cytometry. Up-regulation of CD86, CD80 and CD83 and down-regulation of DCSIGN was observed. In addition, LGG induced secretion of high levels IL-10, INF-γ and IL-1β whereas L.del seemed to be more potent in induction of TNF-α in a dose dependent manner. These results indicated that non-viable forms of both tested strains are able to induce divergent immune regulatory effects via the induction of phenotypic changes and cytokine production of DCs.     

Apolipoproteins L control cell death triggered by TLR3/TRIF signaling in dendritic cells

Apolipoproteins L (ApoLs) are Bcl‐2‐like proteins expressed under inflammatory conditions in myeloid and endothelial cells. We found that Toll‐like receptor (TLR) stimuli, particularly the viral mimetic polyinosinic:polycytidylic acid (poly(I:C)), specifically induce ApoLs7/11 subfamilies in murine CD8α⁺ dendritic cells (DCs). This induction requires the TLR3/TRIF (where TRIF is TIR domain containing adapter‐inducing interferon β) signaling pathway and is dependent on IFN‐β in all ApoLs subfamilies except for ApoL7c. Poly(I:C) treatment of DCs is also associated with induction of both cell death and autophagy. ApoLs expression is related to promotion of DC death by poly(I:C), as ApoLs7/11 knockdown increases DC survival and ApoLs7 are associated with the anti‐apoptotic protein Bcl‐xL (where Bcl‐xL is B‐cell lymphoma extra large). Similarly, in human monocyte‐derived DCs poly(I:C) induces both cell death and the expression of ApoLs, principally ApoL3. Finally, the BH3‐like peptide of ApoLs appears to be involved in the DC death‐promoting activity. We would like to propose that ApoLs are involved in cell death linked to activation of DCs by viral stimuli.     

C反应蛋白与酶修饰低密度脂蛋白对树突状细胞成熟的影响

目的探讨在动脉粥样斑块硬化进程中C反应蛋白（CRP）和酶修饰低密度脂蛋白（E-LDL）对外周血中树突状细胞（DC）分化成熟的影响。方法梯度离心法分离人外周血单核细胞,用含rhGM-CSF和rhIL-4的Cellgro培养液培养5d,使其分化为DC。分别用CRP、E-LDL及CRP加E-LDL刺激DC48h后,采用流式细胞术检测DC表型（CD1a、CD80、CD86、HLA-DR）的表达,ELISA法检测DC上清液中IL-12、TNFα、IL-2和IL-10的含量,并进行比较。结果CRP抑制DC的CD1a、CD80表达及IL-12、TNFα分泌,E-LDL促进DC的CD1a、CD80、CD86和HLA-DR表达及IL-12、TNFα分泌,CPR加E-LDL结果与E-LDL类似。结论CRP抑制DC的活化,E-LDL可促进DC的分化成熟,E-LDL激活DC的作用强于CRP的抑制作用。     

Human Dendritic Cell Interactions with Whole Recombinant Yeast: Implications for HIV-1 Vaccine Development

Defects in number and function of dendritic cells (DCs) have been observed during HIV-1 infection, so therapeutic HIV-1 vaccine approaches that target or activate DCs may improve vaccine immunogenicity. To determine the potential of recombinant Saccharomyces cerevisiae yeast as an HIV-1 vaccine, we investigated interactions between yeast and human DCs. Yeast induced direct phenotypic maturation of monocyte-derived DCs (MDDCs) and enriched blood myeloid DCs (mDCs), but only indirectly matured blood plasmacytoid DCs (pDCs). Yeast-pulsed MDDCs and blood mDCs produced inflammatory cytokines and stimulated strong allo-reactive T cell proliferation. Both blood DC subsets internalized yeast, and when pulsed with yeast recombinant for HIV-1 Gag protein, both stimulated in vitro expansion of Gag-specific CD8⁺ memory T cells. These results suggest that S. cerevisiae yeast have potent adjuvant effects on human DCs. Furthermore, recombinant yeast-derived antigens are processed by human blood DCs for MHC class-I cross-presentation. These DC-targeting characteristics of yeast suggest that it may be an effective vaccine vector for induction of HIV-1-specific cellular immune responses.     

Indolamine 2,3‐dioxygenase expression by monocytes and dendritic cell populations in hepatitis C patients

Dendritic cells (DCs) play an important role in the induction of the primary immune response to infection. DCs may express the tryptophan‐catabolizing enzyme indolamine2,3‐dioxygenase (IDO), which is an inducer of immune tolerance. Because there is evidence that chronic hepatitis C virus (HCV) infection leads to functional impairment of certain DC populations, we analysed IDO expression in DCs and monocytes from chronically infected and recovered HCV patients. The IDO1 and ‐2 expression was increased significantly in the monocytes of chronic HCV patients but, interestingly, not in those from recovered patients. The myeloid DCs from chronically infected HCV patients also showed enhanced IDO1 expression, while no change in either IDO1 or ‐2 was found for plasmacytoid DCs. Up‐regulation of IDO1 gene expression was confirmed by the presence of enhanced kynurenine/tryptophan ratios in the plasma from chronic HCV patients. Increased IDO1 and ‐2 expression was also observed in monocytes from healthy donors infected with an adapted mutant of the HCV JFH‐1 strain ex vivo, confirming a direct effect of HCV infection. These changes in IDO expression could be prevented by treatment with the IDO inhibitor 1‐methyl tryptophan (1‐mT). Furthermore, maturation of monocyte‐derived DCs from chronically infected HCV patients, as well as well as monocyte‐derived DCs infected ex vivo with HCV, was impaired, but this was reversed by 1‐mT treatment. This suggests that IDO inhibitors may be used to treat chronic HCV patients in vivo, in conjunction with current therapies, or to activate DCs from patients ex vivo, such that they can be administered back as a DC‐based therapeutic vaccine.     

PD-L1和PD-L2在树突状细胞上的表达及其生物学意义

探讨小鼠髓系DC (CD8α )中PD L1和PD L2的表达及其在T淋巴细胞活化中的作用。采用mCD4 0L CHO和TNF α分别刺激凋亡肿瘤细胞负载DC 4 8h ;免疫荧光标记检测DC表型 ;RT PCR和realtime PCR检测PD L1和PD L2mRNA转录水平 ;ELISA测定IL 2的分泌水平 ;3 H TdR掺入试验和51Cr释放试验测定DC体外激发T细胞的增殖和细胞毒杀伤率。结果显示 :PD L1和PD L2随着DC的成熟呈上调表达 ,CD4 0配基化DC的PD L1和PD L2均为中度表达 ,TNF α激发的DC为高度表达 ,二者呈现差异性表达 (P <0 0 5 ) ;CD4 0配基化髓系DC分泌IL 2的量明显高于TNF α组 (P <0 0 5 ) ,体外刺激T增殖和激活CTL能力在CD4 0配基化DC组最高 (P <0 0 5 )。提示CD4 0配基化的小鼠髓系DC呈现PD L1和PD L2的中度表达 ,IL 2大量分泌 ,这些均有助于激发有效的特异性免疫应答     

转录因子T-bet表达增强人树突状细胞疫苗诱导的抗肝癌免疫

目的：探讨T-bet在肝癌患者外周血来源的树突状细胞(dendritic cells，DCs)中表达能否增强其诱导抗肿瘤免疫。方法: 取肝癌患者外周血单核细胞，用5 μg/L rhGM-CSF、5 μg/L rhIL-4培养6 d成不成熟DC（iDC），随后加10 μg/L TNF-α诱导成熟DC。用冻融法制备肝癌细胞株HepG2肿瘤抗原，致敏DC，并分组如下： loaded DC/TNF-α（loaded mDC）； loaded DC/TNF-α+IFN-γ（loaded DC/T +I）； loaded DC/T-bet (loaded DC/T-bet)； iDC。体外刺激淋巴细胞。观察T-bet外源表达对DC的表型、混合淋巴细胞反应、肿瘤特异性细胞杀伤效率影响。结果: 外源表达T-bet促进DC/T-bet表型成熟，促进自体混合淋巴细胞反应，诱导分泌出更多的Th1型细胞因子，增强肝癌细胞特异性杀伤效应。结论: T-bet增强DC抗肿瘤免疫性能。     

Immunomodulation by semi-mature dendritic cells: A novel role of Toll-like receptors and interleukin-6

Dendritic cells (DCs) are key players in activation of the adaptive immune system by their ability of antigen presentation to and priming of T cells. An increasing body of evidence suggests that DCs may also play an important role in induction of tolerance, predominantly by induction of regulatory T cells (T_reg). More recently, data have been published on how Toll-like receptor (TLR) ligands and cytokines affect DC differentiation, and how DC subsets might be involved in immunoregulation and tolerance rather than in T cell activation. The most important features of tolerance-inducing DCs appear to be their maturation state and their cytokine secretion pattern. The following types of tolerance-inducing DCs have been reported: immature DCs (DCs^im) or DCs in the steady state (DCs^st), DCs^IL-10, semi-mature DCs^TNF-α, semi-mature DCs^IL-6. With this review article we would like to discuss the aforementioned types of tolerogenic DCs with a focus on semi-mature DCs^IL-6 and discuss their potential role in maintenance of (hepatic or intestinal) immune homeostasis and inflammatory diseases such as inflammatory bowel disease.     

Synergism of nitric oxide and maturation signals on human dendritic cells occurs through a cyclic GMP-dependent pathway

Nitric oxide (NO), generated by phagocytes at inflammation sites, contributes to regulate immune responses through autocrine and paracrine actions on bystander cells. Among the latter are dendritic cells (DCs). Little is known about regulation of DC function by NO, especially in the human system. We exposed human monocyte-derived DCs to the NO donor (z)-1-[2-(2-aminoethyl)-N-(2-ammonioethyl)amino] diazen-1-ium-1,2 diolate (DETA-NO) during their maturation process induced by treatment with tumor necrosis factor alpha or lipopolysaccharide or by CD40 activation. We report here that after exposure to DETA-NO, DCs exhibit a significantly increased ability to activate T lymphocytes stimulated by mycobacterial antigens, Staphylococcus aureus Cowen strain B, allo-antigens, or cross-linking of the CD3-T cell receptor complex. This effect persists after removal of DETA-NO, depends on the generation of cyclic guanosine 5'-monophosphate, and is a result of enhanced release by DCs of soluble factors, in particular interleukin (IL)-12. This modulation of DC function is a result of a synergism between NO and the various maturation stimuli, as neither enhanced T cell activation nor IL-12 release was observed after DC exposure to DETA-NO only. These results provide the first evidence that NO acts as a cosignaling molecule regulating human DC response to maturation stimuli.     

Bacillus anthracis lethal toxin attenuates lipoteichoic acid-induced maturation and activation of dendritic cells through a unique mechanism

Lethal toxin (LT), produced by the gram-positive bacterium Bacillus anthracis, was identified as a major etiologic agent causing anthrax due to its strong immunotoxicity. Gram-positive bacteria express lipoteichoic acid (LTA), which is considered as a counterpart to lipopolysaccharide (LPS) of gram-negative bacteria, but differs from LPS in the structure and function. Since dendritic cells (DCs) are essential for the appropriate initiation of immune response, we investigated the effect of LT on LTA-induced DC maturation using immature DCs prepared by differentiation of C57BL/6 mouse bone marrow cells. When immature DCs were matured with LTA in the presence of LT, the expression of representative markers for DC maturation such as CD80, CD83, and CD86 together with MHC class I and II molecules was inhibited. LT ameliorated the attenuation of endocytic capacity during DC maturation by LTA while such effect was not observed in LPS-matured DCs. Furthermore, exposure to LT resulted in a decrease in the expression of pro-inflammatory cytokines including IL-6, TNF-α, and IL-12p40 in LTA-stimulated DCs as in LPS-stimulated DCs. Interestingly, LT showed a minimal change in LTA-induced IL-1β expression while LT highly enhanced the LPS-induced IL-1β expression. Those inhibitory effects might be associated with LT interference of LTA-signaling pathways mediated through mitogen-activated protein kinases (MAPKs) since LT suppressed phosphorylation of MAPK, which was induced by LTA. Meanwhile, no change was observed in the expression of putative anthrax toxin receptors, TEM8 and CMG2, or Toll-like receptor 2. These results suggest that LT suppresses the maturation and activation of DCs stimulated with LTA, similar to the suppression in the LPS-stimulated DCs, but via a distinct mechanism.     

Bruton's tyrosine kinase defect in dendritic cells from X-linked agammaglobulinaemia patients does not influence their differentiation,maturation and antigen-presenting cell function

X‐linked agammaglobulinaemia (XLA) is a primary immunodeficiency disease characterized by very low levels or even absence of circulating antibodies. The immunological defect is caused by deletions or mutations of Bruton's tyrosine kinase gene (Btk), whose product is critically involved in the maturation of pre‐B lymphocytes into mature B cells. Btk is expressed not only in B lymphocytes but also in cells of the myeloid lineage, including dendritic cells (DC). These cells are professional antigen presenting cells (APC) that play a fundamental role in the induction and regulation of T‐cell responses. In this study, we analysed differentiation, maturation, and antigen‐presenting function of DC derived from XLA patients (XLA‐DC) as compared to DC from age‐matched healthy subjects (healthy‐DC). We found that XLA‐DC normally differentiate from monocyte precursors and mature in response to lipopolysaccharide (LPS) as assessed by de novo expression of CD83, up‐regulation of MHC class II, B7·1 and B7·2 molecules as well as interleukin (IL)‐12 and IL‐10 production. In addition, we demonstrated that LPS stimulated XLA‐DC acquire the ability to prime naïve T cells and to polarize them toward a Th1 phenotype, as observed in DC from healthy donors stimulated in the same conditions. In conclusion, these data indicate that Btk defect is not involved in DC differentiation and maturation, and that XLA‐DC can act as fully competent antigen presenting cells in T cell‐mediated immune responses.     

WT1多肽致敏树突状细胞诱导杀伤K562细胞实验研究

目的：研究来自健康人外周血单个核细胞的树突状细胞（DC）负载WT1多肽抗原，体外诱导产生特异性细胞毒性T淋巴细胞（CTL）对K562细胞的杀伤作用。 方法： 应用重组人粒-巨噬细胞集落刺激因子(rhGM-CSF)、重组人白细胞介素4（rhIL-4）、重组人肿瘤坏死因子α（TNF-α）等细胞因子，自外周血单个核细胞诱导扩增，培养出DC，使DC负载WT1多肽抗原。实验分3组，WT1多肽致敏DC为实验组A，未致敏DC为实验组B，单纯自体淋巴细胞未加DC激活为对照组C，观察CTL对K562细胞的杀伤作用。 结果： 培养出具有典型特征的DC，体外能诱导强烈的同种异体混合淋巴细胞增殖反应。在效靶比为20∶1时，实验组A诱导的CTL对K562细胞的杀伤率为86.1%±26.8%；实验组B为47.1%±20.8%；对照组C为27.7%±15.3% (P＜0.05)。 结论： WT1多肽抗原致敏DC能促使CD8阳性淋巴细胞扩增，并诱导激活特异性CTL，对K562靶细胞具有明显的杀伤作用。     

Nocardia fractions,NLD and NWSM,induce tumor necrosis factor-α secretion in human monocytes: Role of protein kinase C

Nocardia lysozyme digest (NLD) and Nocardia water-soluble mitogen (NWSM) are two fractions derived from Nocardia opaca. In this report, we demonstrated that both fractions elicited significant secretion of tumor necrosis factor-α (TNF-α) in human monocytes. Supernatants from monocytes stimulated with NWSM and low concentrations of NLD displayed a cytotoxic activity against TNF-α-sensitive L929 cells, but supernatants from monocytes stimulated with high concentrations of NLD failed to lyse L929 cells. This latter phenomenon might be related to the secretion of an inactive form of TNF-α or the release of an inhibitor of TNF-α cytotoxic activity. Since it is well established that protein kinase C (PKC) plays a major role in the signaling of several monocyte activators, we investigated the putative role of PKC in cytokine synthesis induced by NLD and NWSM fractions. TNF-α secretion in response to both Nocardia fractions was inhibited by sphingosine, staurosporine and calphostin C, known PKC inhibitors, as well as by a PKC depletion procedure. In addition, NLD and NWSM induced a transient increase in [³H] phorbol dibutyrate binding, which assessed the activation of PKC. The data suggest the involvement of PKC in the signaling of NLD and NWSM fractions leading to the synthesis and the secretion of TNF-α by human monocytes.     

Echinococcus granulosus antigen B impairs human dendritic cell differentiation and polarizes immature dendritic cell maturation towards a Th2 cell response

Despite inducing a strong host cellular and humoral immune response, the helminth Echinococcus granulosus is a highly successful parasite that develops, progresses, and ultimately causes chronic disease. Although surgery remains the preferred therapeutic option, pharmacological research now envisages antihelminthic strategies. To understand the mechanisms that E. granulosus uses to escape host immunosurveillance and promote chronic infection, we investigated how two hydatid cyst components, purified antigen B (AgB) and sheep hydatid fluid (SHF), act on host dendritic cell (DC) differentiation from monocyte precursors and how they influence maturation of DC that have already differentiated. We evaluated the immunomodulatory potential of these antigens by performing immunochemical and cytofluorimetric analyses of monocyte-derived DCs from healthy human donors. During monocyte differentiation, AgB and SHF downmodulated CD1a expression and upregulated CD86 expression. Compared with immature DCs differentiated in medium alone (iDCs), AgB- and SHF-differentiated cells stimulated with lipopolysaccharide included a significantly lower percentage of CD83(+) cells (P < 10(-4)) and had weaker costimulatory molecule expression. When stimulated with AgB and SHF, iDCs matured and primed lymphocytes towards the Th2 response typical of E. granulosus infection. SHF and particularly AgB reduced the production of interleukin-12p70 (IL-12p70) and tumor necrosis factor alpha in lipopolysaccharide-stimulated iDCs. Anti-IL-10 antibodies increased the levels of IL-12p70 secretion in AgB- and SHF-matured DCs. AgB and SHF induced interleukin-1 receptor-associated kinase phosphorylation and activated nuclear factor-kappaB, suggesting that Toll-like receptors could participate in E. granulosus-stimulated DC maturation. These results suggest that E. granulosus escapes host immunosurveillance in two ways: by interfering with monocyte differentiation and by modulating DC maturation.     

Tumour-loaded α-type 1-polarized dendritic cells from patients with chronic lymphocytic leukaemia produce a superior NK-, NKT- and CD8+ T cell-attracting chemokine profile

Tumour-loaded dendritic cells (DCs) from patients with chronic lymphocytic leukaemia (CLL) matured using an α-type 1-polarized DC cocktail (IL-1β/TNF-α/IFN-α/IFN-γ/poly-I:C;αDC1) were recently shown to induce more functional CD8(+) T cells against autologous tumour cells in vitro than DCs matured with the 'standard' cocktail (IL-1β/TNF-α/IL-6/PGE(2) ;PGE(2) DCs). However, the ability of vaccine DCs to induce a type 1-polarized immune response in vivo probably relies on additional features, including their ability to induce a CXCR3-dependent recruitment of NK cells into vaccine-draining lymph nodes. Moreover, their guiding of rare tumour-specific CD8(+) T cells to sites of DC-CD4(+) T cell interactions by secretion of CCL3 and CCL4 is needed. We therefore analysed the chemokine profile and the lymphocyte-attracting ability in vitro of monocyte-derived PGE(2) DCs and αDC1s from patients with CLL. αDC1s produced much higher levels of CXCR3 ligands (CXCL9/CXCL10/CXCL11) than PGE(2) DCs. Functional studies further demonstrated that αDC1s were superior recruiters of both NK and NKT cells. Moreover, αDC1s produced higher levels of CCL3/CCL4 upon CD40 ligation. These findings suggest that functional αDC1s, derived from patients with CLL, produce a desirable NK-, NKT- and CD8(+) T cell-attracting chemokine profile which may favour a guided and Th1-deviated priming of CD8(+) T cells, supporting the idea that αDC1-based vaccines have a higher immunotherapeutic potential than PGE(2) DCs.     

Optimal stimulation for CD70 induction on human monocyte‐derived dendritic cells and the importance of CD70 in naive CD4+ T‐cell differentiation

Studies in mice have shown that CD70 on dendritic cells (DCs) is sufficient to convert T‐cell tolerance into immunity and hence induce anti‐tumour immune responses. Therefore, it is important to investigate (i) optimal stimuli to induce CD70 on human monocyte‐derived DCs (MoDCs), which are widely used for tumour immunotherapy, and (ii) the role of CD70 in functional differentiation of naive CD4⁺ and CD8⁺ T cells stimulated with MoDCs. We show that interferon‐α (IFN‐α) is a key cytokine to differentiate monocytes into DCs with the capacity to express CD70 upon maturation. CD70 expression on IFN‐α‐induced MoDCs was elicited by different categories of maturation‐inducing factors (Toll‐like receptor ligands, CD40 ligand and pro‐inflammatory mediators), among which prostaglandin E₂ was most effective. Naive T cells stimulated with MoDCs also expressed CD70. Stimulation with MoDCs promoted naive CD4⁺ T cells to acquire the ability to produce T helper type 1 and 2 cytokines in a CD70‐dependent manner. In contrast, the CD70–CD27 interaction diminished the production of an immunoregulatory cytokine IL‐10. The CD27 signal did not play a dominant role in the induction of effector molecules in naive CD8⁺ T cells during the stimulation with MoDCs. This study adds a novel function to the versatile cytokines, type I IFNs, that is, the induction of CD70 on MoDCs. CD70 promotes naive CD4⁺ T cells to acquire immunostimulatory activity through the DC–T‐cell and T‐cell–T‐cell interactions during the stimulation with MoDCs. Hence, the CD70–CD27 interaction may play an important role in inducing effective immune responses in DC‐based immunotherapy.