Aberrant Phenotype and Function of Dendritic Cells in Adult B Lineage Acute Lymphoblastic Leukemia

ABSTRACT

Dendritic cells (DCs) play a major role in regulating immune responses, but the aberrant phenotype and function of defective DCs in adult acute lymphoblastic leukemia (ALL) remain unclear. Here, B lineage ALL (B-ALL) patients were divided into groups according to different standards. By course of disease: newly diagnosed (ND), complete remission (CR), consolidation (CONS). By stratification: high risk (HR), standard risk (SR). By minimal residual disease (MRD): MRD positive(MRD+), MRD negative (MRD?). The proportion of plasmacytoid DC(pDC) and myeloid DC(mDC) were compared within these standards. The costimulatory molecule levels of pDC, mDC in ND and CR were measured and the function of peripheral blood monocyte-derived DC(MoDC)s were examined. We found proportions of pDC and mDC in ND were both lower compared to control group and gradually increased after CR. In HR and MRD+, the proportions were also lower compared to SR and MRD? at CR stage, respectively; but there were no difference between these comparisons when newly diagnosed. In ND, both CD80, CD86 levels in pDC, mDC were higher while the levels in activated MoDCs were lower when compared to control and CR group, respectively. The dextran uptake of MoDCs, T cell proliferation promoting ability, IL-12, BAFF, INF-α levels in supernatant and their mRNA relative expression in activated MoDCs in ND were also lower than those in control and CR group. So, DCs in B-ALL display suppressed status in phenotype and function,which would be gradually restored after effective chemotherapy. pDC and mDC could respond to patient condition, DCs proportion may be useful for monitoring disease progression.     

Cord blood dendritic cell subsets in African newborns exposed to Plasmodium falciparum in utero

Placental Plasmodium falciparum infection affects birth outcomes and sensitizes fetal lymphocytes to parasite antigens. We assessed the influence of maternal P. falciparum infection on fetal myeloid dendritic cells (mDC) and plasmacytoid dendritic cells (pDC), analyzing the cord blood of offspring of Gabonese mothers with different infection histories. Cord blood from newborns of mothers with malarial infection at delivery had significantly more mDC than that from nonexposed newborns (P = 0.028) but mDC and pDC HLA-DR expression was unrelated to maternal infection history. Independently of these findings, cord blood mDC and pDC numbers declined significantly as a function of increasing maternal age (P = 0.029 and P = 0.033, respectively). The inducible antigen-specific interleukin-10-producing regulatory-type T-cell population that we have previously detected in cord blood of newborns with prolonged in utero exposure to P. falciparum may directly reflect the altered DC numbers in such neonates, while the maintenance of cord blood DC HLA-DR expression contrasts with that of DC from P. falciparum malaria patients.     

慢性HCV感染者外周血中髓样和浆样树突状细胞频数和表型研究

目的 探讨慢性HCV感染者外周血中髓样树突状细胞(mDC)和浆样树突状细胞(pDC)频数和表型的变化,并分析其与丙型肝炎临床指标间的相关性.方法 采用流式细胞术检测HCV感染者及健康对照外周血中mDC和pDC的频数及细胞表面共刺激分子HLA-DR、CD83、CD86、CD40和共抑制分子PD-L1的表达水平,并分析DC频数与HCV感染者血浆病毒载量、谷丙转氨酶(ALT)的相关性.结果 与健康对照组相比,HCV感染者外周血中mDC和pDC的频数明显降低(患者组分别为0.37±0.19和0.19±0.12,对照组为0.51±0.18和0.29±0.13,P＜0.05),且mDC频数与血浆HCV载量和血清ALT水平呈负相关(r=-0.5878,P＜0.0001;r=-0.4628,P=0.003).患者mDC和pDC表面共刺激分子HLA-DR、CD83、CD86、CD40以及共抑制分子PD-L1的表达均有不同程度升高,差别有统计学意义(共刺激分子P＜0.01,共抑制分子P＜0.05或0.01).结论 慢性HCV感染者外周血mDC和pDC频数下降,但DC表面共刺激分子和共抑制分子的表达均明显升高.该结果提示mDC数量的减少可能与HCV的慢性持续性感染有关.

Abstract：

Objective To explore the frequencies and phenotype of myeloid and plasmacytoid dendritic cells (mDC and pDC) in chronic HCV infection and to investigate the relationships between DC frequencies and HCV viral load and serum ALT level. Methods PBMC were isolated from chronic HCV infected patients and healthy control. Multi-color flow cytometry was used to analyze the frequencies and surface marker expression on mDC and pDC. The relationship between DC frequencies and viral load and ALT level was also calculated. Results In comparison with healthy control, frequencies of mDC and pDC in chronic HCV infection were significantly decreased (0. 37 ± 0. 19 and 0. 19 ± 0. 12 vs 0. 51 ± 0. 18 and 0. 29 ± 0.13, P＜0.05). The frequency of mDC was negatively correlated with HCV viral load (r= -0.5878, P ＜ 0. 0001 ) and serum ALT level ( r = - 0. 4628 , P = 0. 003 ). Both costimulatory markers ( HLA-DR, CD83, CD86, and CD40) and coinhibitory marker (PD-L1) expression on mDC and pDC in HCV infection were increased (P＜0.01 for costimulatory marker, P＜0.05 or F＜0.01 for coinhibitory marker). Conclusion The frequencies of mDC and pDC in chronic HCV infection were decreased, while the expression of costimulatory markers and coinhibitory marker were increased or not decreased in HCV infection. The decreased frequency of mDC was probably related to persistance of HCV infection.     

Type 1 diabetes patients have significantly lower frequency of plasmacytoid dendritic cells in the peripheral blood

Dendritic cells uniquely orchestrate the delicate balance between T cell immunity and regulation and an imbalance favoring immunogenic rather than tolerogenic DC is believed to contribute to the development of autoimmune diseases such as type 1 diabetes (T1D). In this study, we determined the frequencies of three blood DC subsets (pDC, mDC1 and mDC2) in 72 T1D patients and 75 normal controls using the Miltenyi blood DC enumeration kit. The frequency of blood pDC was found to be negatively correlated with subject age in both normal controls and T1D patients (p=0.0007), while the frequency of mDC1 and mDC2 do not change significantly with subject age. More importantly, the mean frequency of pDC in blood was, after adjusting for age, significantly lower in T1D (mean=0.127%) than controls (mean=0.188%) (p<6.0 x 10(-5)), whereas no difference was observed for mDC1 and mDC2 between T1D and controls. Furthermore, T1D patients have a lower proportion of pDC and higher proportion of mDC1 among the total blood DC population than normal controls. These results indicate that the frequency of blood pDC and the pDC/mDC1 ratio are negatively associated with T1D.     

Dendritic Cells in Bone Marrow at Diagnosis and after Chemotherapy in Adult Patients with Acute Myeloid Leukaemia

Dendritic cells (DCs) develop in the bone marrow from haematopoietic progenitor cells. Two subsets, plasmacytoid DCs (pDCs) and myeloid DCs (mDCs), have been identified. Little is known regarding DC levels in bone marrow of patients with acute myeloid leukaemia (AML) before and after chemotherapy. We investigated relative pDC and mDC levels in bone marrow from 37 hospital controls and 60 patients with AML [at diagnosis, complete remission (CR) and follow‐up] using four‐colour flow cytometry. The pDC immunophenotype was characterized as lin‐/HLA‐DR+/CD123 +  and mDC as lin‐/HLA‐DR+/CD11c+. In 69% of patients with AML, no DCs were detected at diagnosis. At CR, mDC levels were the same in patients with AML and hospital controls while pDC levels were slightly lower. There was no association between minimal residual disease or survival rates and DC levels. Patients with low mDC levels at CR were more likely to suffer from complicated infections, although the difference was not statistically significant. Altogether, there was a profound decrease in DC levels in patients with AML at diagnosis. DC levels increased at CR and were higher than in hospital controls after post‐remission therapy, suggesting that DCs recover after repeated chemotherapy. There may be an association between mDC levels and infectious complications.     

Profiling dendritic cell subsets in the patients with active pulmonary tuberculosis

Dendritic cell (DC) plays an important role in the immune response against pulmonary tuberculosis. However, the phenotypic profile of DC subsets in peripheral blood in individuals with active pulmonary tuberculosis (APT) is still inconclusive. Here, we demonstrated that the absolute numbers of total DC (tDC), myeloid DC (mDC) and plasmacytoid DC (pDC) in individuals with APT were decreased compared to healthy controls (HCs). The decreased number of DCs, especially of pDC, seems to be a useful diagnostic marker of APT. Meanwhile, the number of DCs was associated with the prolonged/complicated TB, ATD treatment effect and lymphocyte immune reactions, as manifested that relapsed APT patients with a higher number of tDC and lower number of pDC compared to newly diagnosed patients. Interestingly, mDC from APT patients displayed high expressions of CD83 and CCR7, but pDC displayed low expressions of CD83 and CCR7. Moreover, DCs from APT patients expressed lower levels of HLA-DR and CD80, but expressed a higher level of CD86 than those from HCs. However, the antigen uptake capacity of DC subsets was not different between APT and HCs, despite the antigen uptake capacity of pDC was much lower than that of mDC in both APT patients and HCs. Our data represent a systematic profile of DC subsets in the blood of APT patients, and would represent a useful biomarker for APT.     

慢性乙型肝炎干扰素治疗前后树突状细胞的变化及其与疗效相关性研究

目的 探讨慢乙肝干扰素α(IFNα)治疗前后髓样树突状细胞(mDC)和浆样树突状细胞(pDC)的变化及其与病毒学、生化学指标的关系.方法 采集30例HBeAg阳性慢乙肝患者IFNα治疗前和治疗12周时的外周血,用流式细胞仪检测mDC和pDC的频数及CD86表达水平.根据IFNα治疗后生化学指标和病毒学指标变化,把患者分为ALT复常组、ALT未复常组及病毒学应答组、病毒学无应答组,分析IFNα治疗前后不同组DC变化.结果 (1)IFNα治疗12周时ALT复常组pDC频率(0.25％±0.14％)较基线(0.18％±0.09％)升高(P =0.023),ALT未复常组mDC频率(0.58％±0.34％)及表面CD86阳性率(61.80％±22.52％)则较基线(分别为0.88％±0.51％,79.92％±25.94％)下降(P =0.025;P=0.036).(2)IFNα治疗12周时病毒学应答组pDC表面CD86阳性率(46.86±12.22％)较基线(29.42±15.16％)升高(P =0.002),病毒学无应答组的mDC频率(0.51％±0.22％)及表面CD86阳性率(59.63％±22.94％)则较基线(分别为0.94％±0.58％,80.11％±29.34％)下降(P =0.006;P =0.049).结论 慢乙肝干扰素α治疗后,生化和病毒应答与pDC频率和功能增强相关,而mDC频率及功能的降低与IFN治疗后无生化和病毒应答相关.     

Matrix protein mediated shutdown of host cell metabolism limits vesicular stomatitis virus-induced interferon-alpha responses to plasmacytoid dendritic cells

Upon infection with many different viruses, plasmacytoid dendritic cells (pDC) produce large amounts of type I interferon (IFN-alpha/beta). To address why upon vesicular stomatitis virus (VSV) infection pDC, but not conventional myeloid DC (mDC), are induced to produce IFN-alpha, pDC and mDC were differentiated from bone marrow cells (BM-DC). Upon VSV infection BM-pDC produced IFN-alpha, whereas BM-mDC did not. Notably, upon infection with VSV-M2, a VSV variant expressing a M51R mutant matrix (M) protein that showed a reduced sequestration of host cell metabolism, BM-pDC and BM-mDC mounted massive IFN-alpha responses. Both DC subsets showed comparable RNA levels of retinoic acid inducible gene-I (RIG-I) and Toll-like receptor (TLR) 7 and were able to respond upon triggering with double-stranded RNA (dsRNA) or single-stranded RNA (ssRNA) analogs. Moreover, upon VSV-M2 infection IFN-alpha production by both DC subsets was largely dependent on viral replication. Interestingly, upon virus infection BM-pDC, but not BM-mDC, up-regulated mRNA levels of nuclear export factors Nup96/98, probably reflecting cellular mechanisms to circumvent viral escape strategies. Collectively, these results indicated that cell types induced to produce IFN-alpha upon viral infection are not primarily defined by cellular receptor configurations but rather by complex virus/host cell interactions.     

Maturation and cytokine production potential of dendritic cells isolated from rheumatoid arthritis patients peripheral blood and induced in vitro

BackgroundSince dendritic cells (DC) are involved in the development of autoimmune inflammation, researchers consider DC both as target cells for specific therapy of rheumatoid arthritis (RA) and as candidate cells for the development of cell-based methods to treat autoimmune diseases. The development of treatment strategies requires comprehensive research into the quantitative and qualitative characteristics of DC subtypes both ex vivo from RA patients and in vitro, to determine the possibility of inducing functionally mature DC in RA.ObjectiveTo study the phenotypic and functional properties of myeloid (mDC) and plasmacytoid (pDC) DC isolated from the peripheral blood of patients with RA and induced in vitro.Materials and methodsBlood samples were obtained from RA patients and healthy donors. Immature DC in the whole blood and in vitro induced DC were characterized by the positive expression of CD80, CD83, CCR7, IL-10, IL-4, IL-12 and IFN-α. R848 and lipopolysaccharide were used to determine DC maturation ability. From PBMCs of RA patients and health donors DCs with myeloid (imDC) and plasmacytoid (ipDC) phenotype were induced.ResultsThe relative count of mDC in the peripheral blood between studied groups did not differ. pDC count was significantly lower for RA patients. DC from RA patients were characterized by low expression levels of CD80 and CD83 on both populations cells and high expression of CCR7 only on pDC. An increase in pDC producing IL-12 and IFN-α and a decrease in mDC and pDC producing IL-4 and IL-10 were shown in RA. imDC and ipDC obtained from RA patients according to their phenotype and cytokine profile did not differ from those obtained from healthy donors.ConclusionsThere is an imbalance between subpopulations of DC in the peripheral blood of RA patients. DC of RA patients are less mature. The data suggest the involvement of DC in RA pathogenesis and confirm DC participation in balance shift towards Th1-type immune responses. At the same time, in vitro induced RA DC are phenotypically and functionally competent.     

Preserved Dendritic Cell HLA-DR Expression and Reduced Regulatory T Cell Activation in Asymptomatic Plasmodium falciparum and P. vivax Infection

Clinical illness with Plasmodium falciparum or Plasmodium vivax compromises the function of dendritic cells (DC) and expands regulatory T (Treg) cells. Individuals with asymptomatic parasitemia have clinical immunity, restricting parasite expansion and preventing clinical disease. The role of DC and Treg cells during asymptomatic Plasmodium infection is unclear. During a cross-sectional household survey in Papua, Indonesia, we examined the number and activation of blood plasmacytoid DC (pDC), CD141⁺, and CD1c⁺ myeloid DC (mDC) subsets and Treg cells using flow cytometry in 168 afebrile children (of whom 15 had P. falciparum and 36 had P. vivax infections) and 162 afebrile adults (of whom 20 had P. falciparum and 20 had P. vivax infections), alongside samples from 16 patients hospitalized with uncomplicated malaria. Unlike DC from malaria patients, DC from children and adults with asymptomatic, microscopy-positive P. vivax or P. falciparum infection increased or retained HLA-DR expression. Treg cells in asymptomatic adults and children exhibited reduced activation, suggesting increased immune responsiveness. The pDC and mDC subsets varied according to clinical immunity (asymptomatic or symptomatic Plasmodium infection) and, in asymptomatic infection, according to host age and parasite species. In conclusion, active control of asymptomatic infection was associated with and likely contingent upon functional DC and reduced Treg cell activation.     

The Role of Plasmacytoid and Myeloid Dendritic Cells in Induction of Asthma in a Mouse Model and the Effect of a TLR9 Agonist on Dendritic Cells

Purpose

To determine the role of plasmacytoid dendritic cells (pDC) and myeloid dendritic cells (mDC) in priming effector T cells to induce allergy, and to evaluate the effect of immunostimulatory sequences (ISS, TLR9 agonist) on dendritic cells.

Methods

Cultured mDC and pDC with/without ISS were injected intratracheally into sensitized Balb/C mice. Mice were sacrificed, and then pulmonary function tests, bronchoalveolar lavage (BAL), cell counts, and cytokine levels were evaluated. Migration of dendritic cells was also evaluated after ISS administration.

Results

In mice injected with mDC, airway hyperresponsiveness, eosinophil counts, and Th2 cytokine levels in BAL increased with increasing numbers of mDC injected. However, in mice injected with pDC, none of these changed, suggesting poor priming of T cells by pDC. In addition, mDC pulsed with ISS inhibited asthmatic reactions, and ISS administration inhibited migration of DC to the lung.

Conclusions

We suggest that pDC played a limited role in priming T cells in this asthma model and that mDC played a major role in inducing asthma. In addition, ISS inhibited migration of DC to the lung.     

Circulating dendritic cells and interferon-alpha production in patients with tuberculosis: correlation with clinical outcome and treatment response

Dendritic cells (DC) have been characterized recently as having an important role in the initiation and control of immunological response to Mycobacterium tuberculosis infection. Blood DC have been subdivided into myeloid (mDC) and plasmacytoid (pDC) subsets, on the basis of differences in phenotype markers and function. Little is known about the enumeration and functional evaluation of circulating DC in patients with tuberculosis and their correlation with clinical outcome during the course of anti-tuberculous treatment. We assessed circulating mDC and pDC counts measured by a newly developed single-platform flow cytometric assay based on TruCOUNT, as well as the production of interferon (IFN)-alpha after in vitro stimulation by herpes simplex virus (HSV-1) in 24 patients with active tuberculosis (TB) and 37 healthy donors. Absolute numbers of both DC subsets were decreased significantly in patients with active TB compared to controls. Similarly, the production of IFN-alpha was highly impaired. In 13 patients these parameters were assessed longitudinally, before and after the specific anti-microbial treatment. Most interestingly, in all nine patients with successful anti-tuberculous therapy there was a significant and marked increase of pDC counts and IFN-alpha production. In contrast, no significant longitudinal variations in DC counts and IFN-alpha production were observed in four patients with lack of response to specific treatment. In conclusion, active TB is associated with a defect in blood DC numbers and IFN-alpha production that is restored after bacterial clearance and clinical improvement, as a result of effective anti-tuberculous treatment.     

Altered phenotype and function of dendritic cells in children with type 1 diabetes

The importance of dendritic cells (DC) in the activation of T cells and in the maintenance of self-tolerance is well known. We investigated whether alterations in phenotype and function of DC may contribute to the pathogenesis of Type 1 diabetes (T1DM). Mature DC (mDC) from 18 children with T1DM and 10 age-matched healthy children were tested. mDC, derived from peripheral blood monocytes cultured for 6 days in presence of interleukin (IL)-4 and granulocyte-macrophage colony stimulating factor (GM-CSF) and stimulated with lipopolysaccharide (LPS) for the last 24 h, were phenotyped for the expression of the co-stimulatory molecules B7.1 and B7.2. In six patients and six controls allogenic mixed leucocyte reaction (AMLR) was performed using mDC and cord blood-derived naive T cells at a DC/T naive ratio of 1 : 200. Proliferation was assessed on day 7 by [(3)H]-thymidine incorporation assay. Mature DC derived from patients showed, compared with controls, a reduced expression of B7.1 [mean of fluorescence intensity (MFI): 36.2 +/- 14.3 versus 72.9 +/- 34.5; P = 0.004] and B7.2 (MFI: 122.7 +/- 67.5 versus 259.6 +/- 154.1; P = 0.02). We did not find differences in the HLA-DR expression (P = 0.07). Moreover, proliferative response of allogenic naive T cells cultured with mDC was impaired in the patients (13471 +/- 9917.2 versus 40976 +/- 24527.2 cpm, P = 0.04). We also measured IL-10 and IL-12 concentration in the supernatant of DC cultures. Interestingly, we observed in the patients a sevenfold higher level of IL-10 (P = 0.07) and a ninefold lower level of IL-12 (P = 0.01). Our data show a defect in the expression of the co-stimulatory molecules and an impairment of DC priming function, events that might contribute to T1DM pathogenesis.     

Rapid Disease Progression in HIV-1-Infected Men Who Have Sex with Men Is Negatively Correlated with Peripheral Plasmacytoid Dendritic Cell Counts at the Early Stage of Primary Infection

To explore the relationship between absolute dendritic cell (DC) counts at the early stage of primary human immunodeficiency virus type 1 (HIV-1) infection (PHI) and subsequent disease progression, we performed a prospective study of 16 rapid progressors (RPs) and 12 typical progressors (TPs) from a PHI cohort of men who have sex with men. Significantly decreased plasmacytoid DC (pDC) and myeloid DC (mDC) counts in the blood of RPs were observed at study entry as compared with TPs and healthy HIV-1-negative subjects. Low baseline pDC counts were significantly associated with rapid disease progression after adjustment for baseline CD4(+) T cell counts, mDC counts, and HIV-1 load. Kaplan-Meier survival analysis showed that low pDC counts were strongly associated with rapid disease progression. Our findings demonstrated the predictive value of blood absolute pDC counts at baseline in PHI for HIV-1 disease progression. Further studies are required to confirm this notion.     

Matrix protein mediated shutdown of host cell metabolism limits vesicular stomatitis virus-induced interferon-alpha responses to plasmacytoid dendritic cells

Upon infection with many different viruses, plasmacytoid dendritic cells (pDC) produce large amounts of type I interferon (IFN-/β). To address why upon vesicular stomatitis virus (VSV) infection pDC, but not conventional myeloid DC (mDC), are induced to produce IFN-, pDC and mDC were differentiated from bone marrow cells (BM-DC). Upon VSV infection BM-pDC produced IFN-, whereas BM-mDC did not. Notably, upon infection with VSV-M2, a VSV variant expressing a M51R mutant matrix (M) protein that showed a reduced sequestration of host cell metabolism, BM-pDC and BM-mDC mounted massive IFN- responses. Both DC subsets showed comparable RNA levels of retinoic acid inducible gene-I (RIG-I) and Toll-like receptor (TLR) 7 and were able to respond upon triggering with double-stranded RNA (dsRNA) or single-stranded RNA (ssRNA) analogs. Moreover, upon VSV-M2 infection IFN- production by both DC subsets was largely dependent on viral replication. Interestingly, upon virus infection BM-pDC, but not BM-mDC, up-regulated mRNA levels of nuclear export factors Nup96/98, probably reflecting cellular mechanisms to circumvent viral escape strategies. Collectively, these results indicated that cell types induced to produce IFN- upon viral infection are not primarily defined by cellular receptor configurations but rather by complex virus/host cell interactions.     

The number and function of circulating dendritic cells may limit effector memory CD4+ T-cell responses in HIV patients responding to antiretroviral therapy

Some HIV patients who previously experienced severe immunodeficiency retain low pathogen-specific T-cell responses despite a virological response to antiretroviral therapy (ART). To identify correlates with dysfunction in accessory cell populations, HIV patients were stratified into groups maintaining high or low CD4⁺ T-cell IFN-γ responses to cytomegalovirus (CMV) over 4–8 years on ART. Myeloid dendritic cells (mDC), plasmacytoid (p) DC, M-DC8⁺ cells and monocytes were enumerated and mRNA of cytokines and activation molecules were quantitated in purified subpopulations. Proportions of pDC were lower (p = 0.043) and mDC were higher (p = 0.043) in low responders. TRAIL receptor 2 (DR5) mRNA levels in pDC (p = 0.0008) and mDC (p = 0.0062) were lower in high responders compared to controls. Levels of IL-15 mRNA were higher in mDC from high responders (p = 0.015) and levels of IL-10 mRNA were higher in M-DC8⁺ cells from low responders (p = 0.036). Hence CMV-specific CD4⁺ T-cell IFN-γ responses may be affected by numbers and function of circulating DC.     

Assessment of the effect of ribavirin on myeloid and plasmacytoid dendritic cells during interferon-based therapy of chronic hepatitis B patients

The combination of ribavirin and peginterferon is the current standard of anti-viral treatment for chronic HCV patients. However, little is known on the mode of action of ribavirin in the anti-viral treatment of HCV patients. To investigate the immunomodulatory mechanism of ribavirin, we studied peginterferon alone versus peginterferon and ribavirin in chronic HBV patients. The addition of ribavirin did not affect the number of myeloid dendritic cells (mDC) or plasmacytoid dendritic cells (pDC), nor did it enhance T-helper-1 cell activity or T-cell proliferation. In contrast, it increased upregulation of activation markers on mDC and pDC, which was sustained throughout treatment. However, the addition of ribavirin had no effect on IFNα production by pDC. Our findings demonstrate that, although ribavirin does not lead to a viral load decline, in vivo treatment with ribavirin affects the activation of pDC and mDC in chronic HBV patients.