Extensive characterization of the immunophenotype and pattern of cytokine production by distinct subpopulations of normal human peripheral blood MHC II+/lineage- cells

Dendritic Cells: The Long and Evolving Road towards Successful Targetability in Cancer

Dendritic cells (DCs) are a unique myeloid cell lineage that play a central role in the priming of the adaptive immune response. As such, they are an attractive target for immune oncology based therapeutic approaches. However, targeting these cells has proven challenging with many studies proving inconclusive or of no benefit in a clinical trial setting. In this review, we highlight the known and unknown about this rare but powerful immune cell. As technologies have expanded our understanding of the complexity of DC development, subsets and response features, we are now left to apply this knowledge to the design of new therapeutic strategies in cancer. We propose that utilization of these technologies through a multiomics approach will allow for an improved directed targeting of DCs in a clinical trial setting. In addition, the DC research community should consider a consensus on subset nomenclature to distinguish new subsets from functional or phenotypic changes in response to their environment.

CD133 + cell infusion in patients with colorectal liver metastases going to be submitted to a major liver resection (CELLCOL): A randomized open label clinical trial

BACKGROUND

Treatment of liver metastases of colorectal carcinoma is surgical resection. However, only 10-15% of the patients in this context will be candidate for curative resection arising other 10-13% after response to neoadyuvant chemotherapy. In order to perform the liver metastases surgery, it is necessary to have a sufficient remnant liver volume (RLV) which allows maintaining an optimal liver function after resection. Studies on liver regeneration have determined that CD133 + stem cells are involved in liver hypertrophy developed after an hepatectomy with encouraging results. As presented in previous studies, CD133 + stem cells can be selected from peripheral blood after stimulation with G-CSF, being able to obtain a large number of them. We propose to treat patients who do not meet criteria for liver metastases surgery because of insufficient RLV (<40%) with CD133 + cells together with portal embolization, in order to achieve enough liver volume which avoids liver failure.

METHODS

/Design: The aim of this study is to evaluate the effectiveness of preoperative PVE plus the administration of CD133 + mobilized from peripheral blood with G-CSF compared to PVE only. SECONDARY AIMS ARE: to compare the grade of hypertrophy, speed and changes in liver function, anatomopathological study of hypertrophied liver, to determine the safety of the treatment and analysis of postoperative morbidity and surveillance.

STUDY DESIGN

Prospective randomized longitudinal phase IIb clinical trial, open, to evaluate the efficacy of portal embolization (PVE) together with the administration of CD133 + cells obtained from peripheral blood versus PVE alone, in patients with hepatic metastasis of colorectal carcinoma (CCRHM).

DISCUSSION

The number of CD133 + obtained from peripheral blood after G -CSF stimulation will be far greater than the number obtained with direct puncture of bone marrow. This will allow a greater intrahepatic infusion, which could have a direct impact on achieving a larger and quicker hypertrophy. Consequently, it will permit the treatment of a larger number of patients with an increase on their survival.

TRIAL REGISTRATION

ClinicalTrials.gov, ID NCT03803241.

Classification and clinical behavior of blastic plasmacytoid dendritic cell neoplasms according to their maturation-associated immunophenotypic profile

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare subtype of leukemia/lymphoma, whose diagnosis can be difficult to achieve due to its clinical and biological heterogeneity, as well as its overlapping features with other hematologic malignancies. In this study we investigated whether the association between the maturational stage of tumor cells and the clinico-biological and prognostic features of the disease, based on the analysis of 46 BPDCN cases classified into three maturation-associated subgroups on immunophenotypic grounds. Our results show that blasts from cases with an immature plasmacytoid dendritic cell (pDC) phenotype exhibit an uncommon CD56⁻ phenotype, coexisting with CD34⁺ non-pDC tumor cells, typically in the absence of extramedullary (e.g. skin) disease at presentation. Conversely, patients with a more mature blast cell phenotype more frequently displayed skin/extramedullary involvement and spread into secondary lymphoid tissues. Despite the dismal outcome, acute lymphoblastic leukemia-type therapy (with central nervous system prophylaxis) and/or allogeneic stem cell transplantation appeared to be the only effective therapies. Overall, our findings indicate that the maturational profile of pDC blasts in BPDCN is highly heterogeneous and translates into a wide clinical spectrum -from acute leukemia to mature lymphoma-like behavior-, which may also lead to variable diagnosis and treatment.

Sera from patients with active systemic lupus erythematosus patients enhance the toll-like receptor 4 response in monocyte subsets

Background

Systemic Lupus Erythematosus (SLE) is an auto-immune disease whose complex pathogenesis remains unraveled. Here we aim to explore the inflammatory ability of SLE patients’ sera upon peripheral blood (PB) monocyte subsets and myeloid dendritic cells (mDCs) obtained from healthy donors.

Methods

In this study we included 11 SLE patients with active disease (ASLE), 11 with inactive disease (ISLE) and 10 healthy controls (HC). PB from healthy donors was stimulated with patients’ sera, toll-like receptor (TLR) 4 ligand – lipopolysaccharide or both. The intracellular production of TNF-α was evaluated in classical, non-classical monocytes and mDCs, using flow cytometry. TNF-α mRNA expression was assessed in all these purified cells, after sera treatment.

Results

We found that sera of SLE patients did not change spontaneous TNF-α production by monocytes or dendritic cells. However, upon stimulation of TLR4, the presence of sera from ASLE patients, but not ISLE, significantly increased the intracellular expression of TNF-α in classical and non-classical monocytes. This ability was related to titers anti-double stranded DNA antibodies in the serum. High levels of anti-TNF-α in the patients’ sera were associated with increased TNF-α expression by co-cultured mDCs. No relationship was found with the levels of a wide variety of other pro-inflammatory cytokines. A slight increase of TNF-α mRNA expression was observed in these purified cells when they were cultured only in the presence of SLE serum.

Conclusions

Our data suggest that SLE sera induce an abnormal in vitro TLR4 response in classical and non-classical monocytes, reflected by a higher TNF-α intracellular expression. These effects may be operative in the pathogenesis of SLE.

Human Bone Marrow-Derived Mesenchymal Stromal Cells Differentially Inhibit Cytokine Production by Peripheral Blood Monocytes Subpopulations and Myeloid Dendritic Cells

The immunosuppressive properties of mesenchymal stromal/stem cells (MSC) rendered them an attractive therapeutic approach for immune disorders and an increasing body of evidence demonstrated their clinical value. However, the influence of MSC on the function of specific immune cell populations, namely, monocyte subpopulations, is not well elucidated. Here, we investigated the influence of human bone marrow MSC on the cytokine and chemokine expression by peripheral blood classical, intermediate and nonclassical monocytes, and myeloid dendritic cells (mDC), stimulated with lipopolysaccharide plus interferon (IFN)γ. We found that MSC effectively inhibit tumor necrosis factor- (TNF-) α and macrophage inflammatory protein- (MIP-) 1β protein expression in monocytes and mDC, without suppressing CCR7 and CD83 protein expression. Interestingly, mDC exhibited the highest degree of inhibition, for both TNF-α and MIP-1β, whereas the reduction of TNF-α expression was less marked for nonclassical monocytes. Similarly, MSC decreased mRNA levels of interleukin- (IL-) 1β and IL-6 in classical monocytes, CCL3, CCL5, CXCL9, and CXCL10 in classical and nonclassical monocytes, and IL-1β and CXCL10 in mDC. MSC do not impair the expression of maturation markers in monocytes and mDC under our experimental conditions; nevertheless, they hamper the proinflammatory function of monocytes and mDC, which may impede the development of inflammatory immune responses.

Testosterone replacement therapy in hypogonadal men is associated with increased expression of LAMP-2 (CD107b) by circulating monocytes and dendritic cells

BACKGROUND

Accumulated experimental data indicates that androgen therapy has effects on inflammation and protects from autoimmune disorders. Despite this, the in vivo effects of testosterone replacement therapy on human antigen-presenting cells-for example, monocytes and dendritic cells- remain unknown.

OBJECTIVE, DESIGN AND PATIENTS

We monitored the effects of testosterone replacement therapy on the number and the functionality -as assessed by the expression of CD107b (lysosome-associated membrane protein 2, LAMP-2)- of resting and in vitro-stimulated peripheral blood (classical and nonclassical) monocytes and dendritic cells (myeloid and plasmacytoid) from hypogonadal men.

RESULTS

Our results show that testosterone replacement therapy induces overexpression of CD107b by circulating monocytes and dendritic cells from hypogonadal men, both under resting (i.e. nonstimulated) conditions and after in vitro stimulation. CD107b overexpression mostly involved monocytes and in vitro stimulation with CpG oligodeoxynucleotides. Of note, a strong correlation was found between CD107b expression on monocytes and serum gonadotrophins levels.

CONCLUSION

These results support the existence of an effect of testosterone therapy, and potentially also of gonadotrophins, on circulating antigen-presenting cells.

Maternal circulating dendritic cell subtypes at delivery and during the 1-year postpartum period

PROBLEM

Dendritic cells (DCs) play an important role in maintaining pregnancy by inducing tolerance toward the fetus. Such an immunologic change in the mother should be restored to normal after delivery, but few studies have reported postpartum maternal immune recovery, in terms of the types circulating DCs.

METHOD OF STUDY

The level of each DC subtype and HLA-DR-positive immunoreactivity of the blood from 29 pregnant women with uncomplicated labor was serially analyzed by flowcytometry at delivery and at 1.5, 6, and 12 months after delivery. DC subtypes were characterized as myeloid, lymphoid, and less differentiated (ldDC). Mean fluorescence intensity (MFI) was evaluated for HLA-DR expression for each DC subtype.

RESULTS

The total number and the percentage of DCs at delivery were lower than those at 12 months postpartum. The ldDC fractions were significantly higher at delivery and at 1.5 months than at 12 months postpartum. The MFI of HLA-DR expression on ldDCs at delivery was lower than that at 12 months postpartum. The myeloid-to-lymphoid DC ratio did not differ over the 1-year postpartum period.

CONCLUSION

The maternal alteration in DCs rapidly normalized within 1.5 months, except for the ldDC fraction, which persisted between 1.5 and 6 months after delivery.

Uptake and delivery of antigens by mesenchymal stromal cells

BACKGROUND AIMS

Mesenchymal stromal cells (MSCs) are multipotent stem cells with immunosuppressive properties. Nevertheless, it has been previously reported that MSCs might also trigger the immune response. We studied whether MSCs may act as carriers, capturing antigens that can be endocytosed by antigen-presenting cells later on.

METHODS

We measured the cellular uptake of mannose receptor-mediated fluid phase macropinocytosis, assessed as cellular uptake of fluorescein isothiocyanate-dextran, and PKH-67-labeled cell lysates as a surrogate marker for antigen capture among dendritic cells (DCs, positive control), T lymphocytes (negative control) and MSCs.

RESULTS

All experiments confirmed that MCSs displayed pinocytic and endocytic capacities, which were lower than those observed for DCs but significantly higher than those observed for T cells. We also demonstrated that MSCs release previously endocytosed antigens, which subsequently can be captured by DCs.

CONCLUSIONS

MSCs have the ability to capture and release antigens.

Enhanced immunological response by dendritic cells in male hypogonadism

BACKGROUND

The effect of male hypogonadism on the immune response is poorly understood, even though testosterone has both immunosuppressive and anti-inflammatory effects in men.

DESIGN

In this study, we compared the distribution and functional status of peripheral blood (PB) monocytes, dendritic cells (DCs) [CD16(+) (monocytoid), CD33(+) (myeloid) and CD33(-) (plasmacytoid)] and CD4(+) CD25(+)CD127(-/lo) regulatory T cells from hypogonadic men and control subjects. Immunophenotypic studies were performed both on resting and in vitro-stimulated cells.

RESULTS

Overall, no significant differences were detected on the number of monocytes, DCs and CD4(+) CD25(+) CD127(-/lo) regulatory T cells between both groups of subjects. However, hypogonadic men showed slightly higher numbers of circulating CD16(+) cells expressing the CD107b activation/degranulation-associated marker than controls, such differences reaching statistical significance after in vitro stimulation with CpG oligodeoxynucleotides. Interestingly, antigen-stimulated expression of CD107b on CD16(+) cells inversely correlated with the serum concentrations of total testosterone (r(2)=-0.45; P=0.01), free testosterone (r(2)=-0.48; P=0.005), calculated free testosterone (r(2)=-0.44; P=0.01) and bioavailable testosterone (r(2)=-0.46; P=0.008) among all cases studied, as well as with both the LH (r(2)=-0.53, P=0.04) and FSH (r(2)=-0.54, P=0.04) serum levels among hypogonadic men.

CONCLUSIONS

These findings show an enhanced immunological response of circulating (activated) CD16(+) DCs to antigen stimulation, which was inversely related to testosterone and gonadotropin serum levels. Such findings suggest a modulation by the hypothalamic-hypophyseal-gonadal axis of the immune response and may have clinical implications for hypogonadic men, as regards susceptibility to autoimmune diseases and increased responses to antigenic stimuli.

Analysis of the immune system of multiple myeloma patients achieving long-term disease control by multidimensional flow cytometry

Multiple myeloma remains largely incurable. However, a few patients experience more than 10 years of relapse-free survival and can be considered as operationally cured. Interestingly, long-term disease control in multiple myeloma is not restricted to patients with a complete response, since some patients revert to having a profile of monoclonal gammopathy of undetermined significance. We compared the distribution of multiple compartments of lymphocytes and dendritic cells in the bone marrow and peripheral blood of multiple myeloma patients with long-term disease control (n=28), patients with newly diagnosed monoclonal gammopathy of undetermined significance (n=23), patients with symptomatic multiple myeloma (n=23), and age-matched healthy adults (n=10). Similarly to the patients with monoclonal gammopathy of undetermined significance and symptomatic multiple myeloma, patients with long-term disease control showed an expansion of cytotoxic CD8(+) T cells and natural killer cells. However, the numbers of bone marrow T-regulatory cells were lower in patients with long-term disease control than in those with symptomatic multiple myeloma. It is noteworthy that B cells were depleted in patients with monoclonal gammopathy of undetermined significance and in those with symptomatic multiple myeloma, but recovered in both the bone marrow and peripheral blood of patients with long-term disease control, due to an increase in normal bone marrow B-cell precursors and plasma cells, as well as pre-germinal center peripheral blood B cells. The number of bone marrow dendritic cells and tissue macrophages differed significantly between patients with long-term disease control and those with symptomatic multiple myeloma, with a trend to cell count recovering in the former group of patients towards levels similar to those found in healthy adults. In summary, our results indicate that multiple myeloma patients with long-term disease control have a constellation of unique immune changes favoring both immune cytotoxicity and recovery of B-cell production and homing, suggesting improved immune surveillance.

Dendritic cells in cord blood transplantation: a review

Dendritic cells (DCs) are a heterogeneous population of antigen-presenting cells derived from hematopoietic progenitors that bridge the transition between the innate and adaptive immune responses, while maintaining self-tolerance and Th1/Th2 homeostasis, by priming other cells in either an immunogenic or tolerogenic direction. Through their role in both innate and adaptive immunity, DCs play a major part in transplant engraftment and rejection and in graft-versus-host disease (GvHD). Preferentially tolerogenic or immunogenic DC subtypes offer targets for immunotherapy, to optimize transplant success rates and prolong disease-free and overall survival. Cord blood DCs are immature and preferentially tolerogenic, due to maternal-fetal tolerance, leading to better graft acceptance and immune reconstitution and explaining the lower incidence and severity of GvHD in CB transplantation, despite donor-host mismatching. Manipulation of DC maturation and cell loading with tumor-antigens can direct antitumor immunity and target minimal residual disease, as demonstrated for acute myeloid leukemia, optimizing the graft-versus-leukemia effect.

Insights into the cellular origin and etiology of the infant pro-B acute lymphoblastic leukemia with MLL-AF4 rearrangement

Infant acute lymphoblastic leukemia (ALL) involving mixed-lineage leukemia (MLL) fusions has attracted a huge interest in basic and clinical research because of its prenatal origin, mixed-lineage phenotype, dismal prognosis and extremely short latency. Over 90% of infant ALLs are pro-B ALL harboring the leukemic fusion MLL-AF4. Despite the fact that major achievements have provided a better understanding about the etiology of infant MLL-AF4+ ALL over the last two decades, key questions remain unanswered. Epidemiological and genetic studies suggest that the in utero origin of MLL rearrangements in infant leukemia may be the result of prenatal exposure to genotoxic compounds. In fact, chronic exposure of human embryonic stem cells (hESCs) to etoposide induces MLL rearrangements and makes hESC more prone to acquire subsequent chromosomal abnormalities than postnatal CD34(+) cells, linking embryonic exposure to topoisomerase II inhibitors to genomic instability and MLL rearrangements. Unfortunately, very little is known about the nature of the target cell for transformation. Neuron-glial antigen 2 expression was initially claimed to be specifically associated with MLL rearrangements and was recently shown to be readily expressed in CD34+CD38+, but not CD34+CD38- cells suggesting that progenitors rather than stem cells may be the target cell for transformation. Importantly, the recent findings showing that MLL-AF4 rearrangement is present and expressed in mesenchymal stem cells from infant patients with MLLAF4+ ALL challenged our current view of the etiology and cellular origin of this leukemia. It becomes therefore crucial to determine where the leukemia relapses come from and how the tumor-stroma relationship is defined at the molecular level. Finally, MLL-AF4 leukemogenesis has been particularly difficult to model and bona fide MLL-AF4 disease models do not exist so far. It is likely that the current disease models are missing some essential ingredients of leukemogenesis in the human embryo/fetus. We thus propose modeling MLL-AF4+ infant pro-B ALL using prenatal hESCs.

Mannose-binding lectin deficiency influences innate and antigen-presenting functions of blood myeloid dendritic cells

Mannose-binding lectin (MBL) is a serum lectin that plays a significant role in innate host defence. Individuals with mutations in exon 1 of the MBL2 gene have reduced MBL ligand binding and complement activation function and increased incidence of infection. We proposed that, during infection, MBL deficiency may impact on dendritic cell (DC) function. We analysed the blood myeloid DC (MDC) surface phenotype, inflammatory cytokine production and antigen-presenting capacity in MBL-deficient (MBL-D) individuals and MBL-sufficient (MBL-S) individuals using whole blood culture supplemented with zymosan (Zy) or MBL-opsonized zymosan (MBL-Zy) as a model of infection. Zy-stimulated MDCs from MBL-D individuals had significantly increased production of interleukin (IL)-6 and tumour necrosis factor (TNF)-α. Stimulation with MBL-Zy significantly decreased IL-6 production by MDCs from MBL-D, but had no effect on TNF-α production. MDCs from both MBL-S and MBL-D individuals up-regulated expression of the activation molecule CD83, and down-regulated expression of homing (CXCR4), adhesion (CD62L, CD49d) and costimulatory (CD40, CD86) molecules in response to Zy and MBL-Zy. MDC from both MBL-D and MBL-S individuals induced proliferation of allogeneic (allo) T cells following Zy or MBL-Zy stimulation; however, MBL-D individuals demonstrated a reduced capacity to induce effector allo-T cells. These data indicate that MBL deficiency is associated with unique functional characteristics of pathogen-stimulated blood MDCs manifested by increased production of IL-6, combined with a poor capacity to induce effector allo-T-cell responses. In MBL-D individuals, these functional features of blood MDCs may influence their ability to mount an immune response.

Bone marrow cells from myelodysplastic syndromes show altered immunophenotypic profiles that may contribute to the diagnosis and prognostic stratification of the disease: a pilot study on a series of 56 patients

A heterogeneous spectrum of immunophenotypic abnormalities have been reported in myelodysplastic syndromes (MDS). However, most studies are restricted to the analysis of CD34(+) cells and/or other major subsets of CD34(-) cells, frequently not exploring the diagnostic and prognostic impact of immunophenotyping.

METHODS

We propose for the first time an immunophenotypic score (IS) based on the altered distribution and immunophenotypic features of maturing/mature compartments of bone marrow (BM) hematopoietic cells in 56 patients with MDS that could contribute to a refined diagnosis and prognostic evaluation of the disease.

RESULTS

Although MDS-associated phenotypes were detected in reactive BM, the overall immunophenotypic profile of BM cells allowed an efficient discrimination between MDS and both normal and reactive BM, once the number and degree of severity of the abnormalities detected per patient were simultaneously considered in the proposed IS. Interestingly, increasingly higher IS were found among patients with MDS showing adverse prognostic factors and in low- versus high-grade cases. The most informative prognostic factors included the number of CD34(+) cells, presence of aberrant CD34(-)/CD117(+) precursors, decreased mature neutrophils and CD34(-) erythroid precursors, and increased numbers of CD36(-/lo) erythroid precursors; in addition, the IS was an independent prognostic factor for overall survival.

CONCLUSIONS

Assessment of immunophenotypic abnormalities of maturing/mature BM cells allows an efficient discrimination between MDS and both normal and reactive BM, once the number and degree of severity of the abnormalities detected are simultaneously scored. Interestingly, progressively higher IS were found among patients with MDS with adverse prognostic features and shorter overall survival.

Differences in circulating dendritic cell subtypes in pregnant women, cord blood and healthy adult women

Different subtypes of dendritic cells (DC) influence the differentiation of naíve T lymphocytes into T helper type 1 (Th1) and Th2 effector cells. We evaluated the percentages of DC subtypes in peripheral blood from pregnant women (maternal blood) and their cord blood compared to the peripheral blood of healthy non pregnant women (control). Circulating DC were identified by flow cytometry as lineage (CD3, CD14, CD16, CD19, CD20, and CD56)-negative and HLA-DR-positive cells. Subtypes of DC were further characterized as myeloid DC (CD11c(+)/CD123(+/-)), lymphoid DC (CD11c(-)/CD123(+++)) and less differentiated DC (CD11c(-)/CD123(+/-)). The frequency of DC out of all nucleated cells was significantly lower in maternal blood than in control (P<0.001). The ratio of myeloid DC/lymphoid DC was significantly higher in maternal blood than in control (P<0.01). HLA-DR expressions of myeloid DC as mean fluorescence intensity (MFI) were significantly less in maternal blood and in cord blood than in control (P<0.001, respectively). The DC differentiation factors, TNF-alpha and GM-CSF, released from mononuclear cells after lipopolysaccharide stimulation were significantly lower in maternal blood than in control (P<0.01). The distribution of DC subtypes was different in maternal and cord blood from those of non-pregnant women. Their role during pregnancy remains to be determined.

CD22 expression on blastic plasmacytoid dendritic cell neoplasms and reactivity of anti-CD22 antibodies to peripheral blood dendritic cells

We identified CD22 expression on a blastic plasmacytoid dendritic cell (pDC) neoplasm presenting as a leukemia in a child. CD22 expression, as determined by the antibody s-HCL-1, was also noted on the neoplastic cells from three additional patients with blastic pDC tumors identified at our institution. Subsequently we determined that peripheral blood pDCs react with the s-HCL-1 antibody demonstrating that normal pDCs express CD22. Evaluation of five additional anti-CD22 antibodies indicated that staining of pDCs with these reagents was poor except for s-HCL-1. Therefore, the detection of CD22 on pDCs is best demonstrated with the use of this specific antibody clone. All anti-CD22 antibodies stained conventional DCs. We also evaluated the reactivity of the anti-CD22 antibodies with basophils and noted that the pattern of staining was similar to that seen with pDCs. The studies demonstrate that normal DCs and pDC neoplasms express CD22, and highlight clone specific differences in anti-CD22 antibody reactivity patterns on pDCs and basophils.

Abnormal immunological profile and vaginal microbiota in women prone to urinary tract infections

The host determinants of susceptibility to recurrent urinary tract infections (UTI) are poorly understood. We investigated whether the susceptibility is associated with abnormalities in the immunological defense and further explored the linkage to vaginal microbiota. For this purpose, we compared vaginal, urine, and blood samples collected during a disease-free period from 22 women with recurrent UTI and from 17 controls. In UTI-prone women, interleukin-12 (IL-12) production in peripheral monocytes and myeloid dendritic cells (DCs) was significantly (P < 0.05) enhanced whether measured in relative numbers of IL-12-producing cells or in mean IL-12 production per cell. In contrast, no T-cell polarization was observed. Interestingly, it seemed that the cytokine production of DCs and monocytes did not translate into T-cell activation in the UTI-prone group in a manner similar to that seen with the controls. In vaginal mucosa, UTI-prone women had a lower concentration of tissue repair-associated vascular endothelial growth factor (VEGF) (P = 0.006) and less often had detectable amounts of the chief monocyte and DC chemoattractant, monocyte chemotactic protein 1 (P = 0.005), than the controls. The microbiota of UTI-prone women was characterized by a diminished lactobacillus morphotype composition, with an abnormally high (>3) mean Nugent score of 4.6 compared to 1.7 for the controls (P = 0.003). Normal lactobacillus composition was associated with increased IL-17 and VEGF concentrations in vaginal mucosa. In conclusion, immunological defects and a persistently aberrant microbiota, a lack of lactobacilli in particular, may contribute to susceptibility to recurrent UTI. Further studies of antigen-presenting-cell function and T-cell activation in recurrent UTI are called for.

Cord blood dendritic cells prevent the differentiation of naïve T-helper cells towards Th1 irrespective of their subtype

Allogeneic cord blood transplantation is associated with a less severe graft-versus-host disease (GVHD). This observation is thought to be due to immaturity of cord blood cell immune capabilities. Dendritic cells (DCs) are the most potent antigen-presenting cells of the immune system capable of initiation and regulation of immune responses. In this investigation, we hypothesized that non-manipulated cord blood dendritic cells (CBDCs) not only differ in their functional maturity from adult peripheral blood DCs (PBDCs) but also differ in their subsets and their preference in promoting Th1 or Th2 immune responses. Non-manipulated fresh DCs were isolated from cord blood (CB) and adult peripheral blood (PB) mononuclear cells as lineage marker negative cells. The differences in expression of costimulatory molecules, the proportion of myeloid and lymphoid DCs subsets, their immunostimulatory characteristics and their influence on promoting the differentiation of naïve T cells towards Th1 or Th2 cells were then investigated in these two populations. Our results showed that freshly isolated CBDCs, similar to cord blood monocyte derived DCs, were poor inducers of IFN-gamma secretion while they increased the induction of IL-4 production by T cells in comparison with PBDCs. CBDCs were also poor stimulators of allogenic T cells in mixed leukocyte reaction compared to adult peripheral blood dendritic cells. They also displayed decreased expression of HLA-DR and CD86 molecules. The ratio of lymphoid DCs (CD11c(-), CD123(+)) to myeloid DCs (CD11c(+), CD123(-)) was significantly higher in CB compared to PB. We conclude that CBDCs preferential priming of naive T cells towards Th2 population, seems to be an intrinsic property independent of their subtype. This property along with their functional immaturity should contribute to outcome of cord blood transplantation.

Immunophenotypic identification, enumeration, and characterization of human peripheral blood dendritic cells and dendritic-cell precursors

Study of dendritic cells is complicated by their low frequency and the lack of specific markers for sensitive and specific identification. Furthermore, these cells are not a homogeneous population, but contain a variety of subsets. Flow cytometry has well-established applications for the analysis of cells present at low frequencies; the use of a two-step acquisition procedure increases the number of cells for analysis. This unit presents protocols for the identification and enumeration of dendritic cells and cell subsets in erythrocyte-lysed whole peripheral blood. Special attention is paid to the combinations of reagents used for the identification of all dendritic cells as well as each subset, and on the multiparametric gating strategies for specific analysis.

Persistence of androgenic effects on the production of proinflammatory cytokines by circulating antigen-presenting cells after withdrawal of testosterone treatment in aging type 2 diabetic men with partial androgen deficiency

OBJECTIVE

To test the hypothesis that T treatment withdrawal could be associated with an enhancement of proinflammatory cytokine production by peripheral blood monocytes and dendritic cells.

DESIGN

A prospective intervention study.

SETTING

Tertiary university hospital.

PATIENT(S)

Thirteen type 2 diabetic men aged >55 years with partial androgen deficiency and eight age-matched healthy men (controls).

INTERVENTION(S)

Analyses were performed before and 12 months after T replacement therapy and the results compared with those obtained for the same patients after a 3-month T withdrawal period.

MAIN OUTCOME MEASURE(S)

Distribution of circulating T, B, and natural killer lymphocytes, monocytes, and CD33(hi) myeloid, CD16+, and plasmacytoid dendritic cell subsets. Spontaneous and stimulated ex vivo production of inflammatory cytokines (interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha) by circulating monocytes and dendritic cells, which represent the most potent antigen-presenting cells.

RESULT(S)

The reduction or complete abrogation of spontaneous ex vivo production of proinflammatory cytokines by monocytes and dendritic cells observed after 12 months of T replacement therapy was maintained 3 months after T withdrawal.

CONCLUSION(S)

These are the first results showing that exogenous T treatment deprivation is not associated with an immunologic enhancement of proinflammatory cytokine production by antigen-presenting cells.

Interactions between osteosarcoma cell lines and dendritic cells immune function: An in vitro study

Dendritic cells (DCs) might be partly responsible for the defective immune response in tumor bearing hosts, but no study in osteosarcoma patients is still available. Therefore, we investigated in vitro whether human osteosarcoma cell lines have an inhibitor effect on different types of DCs: CD14+DCs, DC1 and DC2. DCs derived from healthy donors were cultured with osteosarcoma cell lines and appropriate cytokine cocktails and analysed for the expression of co-stimulatory molecules (CD40, CD80, CD83, CD86, HLA-DR). Each interaction resulted in a lower phenotypic expression of the DCs maturation markers, especially on DC2. Moreover, the addition of various cytokines and compounds (rhIL-12, CD40L, Indometacin) induced the DC1 and DC2 subsets towards the Th1 pattern as shown by ELISA. Osteosarcoma highly interferes with an in vitro DCs immune function as antigen presenting cells. The understanding of tumor biology underlines the need for a specific osteosarcoma immunotherapy able to reverse this immune-surveillance inhibition.

Peripheral blood dendritic cell subsets from patients with monoclonal gammopathies show an abnormal distribution and are functionally impaired

Objectives. The information currently available about dendritic cells (DCs) in patients with different types of monoclonal gammopathy (MG) is limited and frequently controversial. In the present study, we analyzed the ex vivo distribution as well as the phenotypic and functional characteristics of peripheral blood (PB) DCs from different types of MG. Methods. For this purpose, 61 untreated patients in total with MG were analyzed-MG of undetermined significance (MGUS), 29 cases; multiple myeloma (MM), 28 cases; and plasma cell leukemia (PCL), 4 cases-in comparison with a group of 10 healthy controls. Results. Our results show an absolute overall higher number of all subsets of PB DCs in PCL, together with lower numbers of myeloid DCs in MM patients. From a phenotypic point of view, PB DC subsets from all types of MG expressed significantly higher levels of HLA molecules and altered patterns of expression of the CD2, CD11c, CD16, CD22, CD62L, and CD86 molecules, in association with altered patterns of secretion of inflammatory cytokines. Conclusion. In summary, we show the existence of significant abnormalities in the distribution, phenotype, and pattern of secretion of inflammatory cytokines by different subsets of PB DCs from patients with MGs, which could reflect a potentially altered homing of DCs, together with a greater in vivo activation and lower responsiveness of PB DCs, which are already detectable in MGUS patients.

Effect of SIVmac infection on plasmacytoid and CD1c+ myeloid dendritic cells in cynomolgus macaques

Dendritic cells (DCs) are known to be essential for the induction and regulation of immune responses. Non-human primates are essential in biomedical research and contribute to our understanding of the involvement of DCs in human infectious diseases. However, no direct single-platform method for quantifying DC precursors has yet been optimized in macaques to give accurate absolute blood counts of these rare-event cell populations in the blood. We adapted a rapid whole-blood assay for the absolute quantification of DCs in cynomolgus macaques by four-colour flow cytometry, using a single-platform assay compatible with human blood. Cynomolgus macaque plasmacytoid DCs (pDCs) and CD1c(+) myeloid DCs (CD1c(+) mDCs) were quantified in the blood of 34 healthy macaques and the results obtained were compared with those for blood samples from 11 healthy humans. In addition, circulating absolute numbers of pDCs were quantified in cynomolgus macaques chronically infected with SIVmac. During infection, pDC counts decreased whereas circulating CD1c(+) mDC counts increased. Information regarding absolute pDC and mDC counts in non-human primates may improve our understanding of the role of these cells in SIV/HIV infection and in other infectious diseases.

Anti-inflammatory effects of probiotic yogurt in inflammatory bowel disease patients

Our aim was to assess anti-inflammatory effects on the peripheral blood of subjects with inflammatory bowel disease (IBD) who consumed probiotic yogurt for 1 month. We studied 20 healthy controls and 20 subjects with IBD, 15 of whom had Crohn's disease and five with ulcerative colitis. All the subjects consumed Lactobacillus rhamnosus GR-1 and L. reuteri RC-14 supplemented yogurt for 30 days. The presence of putative regulatory T (T(reg)) cells (CD4(+) CD25(high)) and cytokines in T cells, monocytes and dendritic cells (DC) was determined by flow cytometry from peripheral blood before and after treatment, with or without ex vivo stimulation. Serum and faecal cytokine concentrations were determined by enzyme-linked immunosorbent assays. The proportion of CD4(+) CD25(high) T cells increased significantly (P = 0.007) in IBD patients, mean (95% confidence interval: CI) 0.84% (95% CI 0.55-1.12) before and 1.25% (95% CI 0.97-1.54) after treatment, but non-significantly in controls. The basal proportion of tumour necrosis factor (TNF)-alpha(+)/interleukin (IL)-12(+) monocytes and myeloid DC decreased in both subject groups, but of stimulated cells only in IBD patients. Also serum IL-12 concentrations and proportions of IL-2(+) and CD69(+) T cells from stimulated cells decreased in IBD patients. The increase in CD4(+) CD25(high) T cells correlated with the decrease in the percentage of TNF-alpha- or IL-12-producing monocytes and DC. The effect of the probiotic yogurt was confirmed by a follow-up study in which subjects consumed the yogurt without the probiotic organisms. Probiotic yogurt intake was associated with significant anti-inflammatory effects that paralleled the expansion of peripheral pool of putative T(reg) cells in IBD patients and with few effects in controls.

Decrease and dysfunction of dendritic cells correlate with impaired hepatitis C virus-specific CD4+ T-cell proliferation in patients with hepatitis C virus infection

Through the production of stimulatory and suppressive cytokines, dendritic cells (DCs) regulate virus-specific immune responses that are crucial to virus eradication. To explore a possible role of DCs in the persistence of hepatitis C virus (HCV) infection, in this study we analysed peripheral blood DCs (PBDCs) in patients with chronic hepatitis C (CHC) compared with those in both healthy seronegative (HSN) controls and a group of subjects who had spontaneously resolved infection, defined as healthy HCV-seropositive (HSP), and we evaluated the relationships between PBDCs and HCV-specific CD4(+) T-cell reactivity. The number of PBDCs, their immunophenotype and expression of regulatory cytokines were evaluated by flow cytometry on whole-blood samples. HCV-specific CD4(+) T-cell activation, proliferation and cytokine production were evaluated in cultures of peripheral blood mononuclear cells (PBMCs) stimulated in vitro with HCV peptides. We found that PBDCs from CHC subjects were numerically reduced and showed lower interleukin-12 (IL-12) and higher IL-10 expression than those from HSN controls. PBDCs from HSP subjects were similar to those from HSN controls. HCV-specific CD4(+) T-cell proliferation was less frequent and vigorous in CHC than in HSP patients and was directly related to the number of PBDCs and their IL-12 production but inversely related to their IL-10 production. Taken together, these results seem to suggest that cytokines of DC origin contribute to the regulation of HCV-specific immunity in CHC patients and indicate that PBDCs may represent a novel non-invasive tool for immune monitoring of these patients.

Injury of skeletal muscle and specific cytokines induce the expression of gap junction channels in mouse dendritic cells

Dendritic cells (DCs) in culture express at least connexin43, a protein subunit of gap junctions, and form gap junction channels, which could be important for T-cells activation. Here, we evaluated whether DCs express connexins in vivo and also to identify components of their microenvironment that regulate the functional expression of gap junctions. In vivo studies were performed in lymph nodes of mice under control conditions or after skeletal muscle damage. In double immunolabeling studies, connexin45 was frequently detected in DEC205(+) DCs in lymph nodes of control animals, whereas connexin43 was rarely found in DCs. However, connexin43 was upregulated in DCs after skeletal muscle damage. Upregulation of connexin43 gene expression by tissue damage was also confirmed in mice carrying a beta-galactosidase reporter gene in a connexin43 allele. The effect of several cytokines on the expression of functional gap junctions between cultured DCs was also tested. Under control conditions, cultured DCs did not communicate via gap junctions. However, after treatment with keratinocyte-conditioned medium or cytokine mixtures containing at least TNF-alpha and IL-1beta, they became transiently coupled through a pathway sensitive to octanol, a gap junction blocker. Cellular coupling induced by effective cytokine mixtures was prevented by IL-6. Single cytokines (TNF-alpha, IL-1beta, IFN-gamma, or IL-6) or other mixtures than the described above did not induce coupling via gap junctions. Increased levels of connexin43 and connexin45 protein and mRNA accompanied the appearance of cellular coupling. These studies provide demonstration of connexin expression and regulation by specific danger signals in DCs.

Decreased blood dendritic cell counts in type 1 diabetic children

In this study DC numbers, phenotype and DC responses to the Toll-like receptor (TLR)-3 ligand, poly I:C, were examined in new-onset Type 1 diabetes (T1D) patients (ND) and in established T1D patients (ED). Absolute blood myeloid DC (MDC) and plasmacytoid DC (PDC) numbers were decreased in ND and ED patients compared to age-matched controls. The decrease in MDC and PDC counts was less evident in patients with a combination of T1D and coeliac disease (CD) or CD alone. The age-dependent decline in blood DC numbers, found in control children, was not evident in ND patients, such that 2-10 years old ND children had similar MDC and PDC numbers to 15-17 years old controls. In ED patients the t-score of MDC and PDC numbers related to the age of diagnosis but not to disease duration. Blood DC in T1D patients were not distinguished from those of controls by the levels of HLA-DR, CD40 and CD86 expression or the percentage of DC expressing cytokines, IL-12, IL-10, IL-6 and TNF-alpha, in responses to poly I:C. If low DC numbers are shown to contribute to the autoimmunity in T1D, interventions aimed to increase DC numbers may mitigate against beta-cell loss.

Early activation markers of human peripheral dendritic cells

Two major populations of dendritic cells (DCs), myeloid and plasmacytoid, can be isolated from human peripheral blood, and are distinguished by differential expression of the cell surface markers CD11c and CD123. These two populations of DCs also are different in their expression of Toll-like receptor (TLRs), which are involved in their activation. To investigate the early events during activation of peripheral DCs, the cells were stimulated in vitro with ligands for TLR-4 (as in lipopolysaccharides [LPS]) or TLR-9 (CpG-containing oligonucleotide [CpG]). The earliest change in protein expression detected after stimulating peripheral DCs with lipopolysaccharide (LPS) or CpG was increased production of the chemokine interleukin (IL)-8. Enhanced production of IL-8 occurred already within 2 hours of stimulation in both myeloid dendritic cells (M-DCs) and plasmacytoid dendritic cells (P-DCs), and preceded expression of the well established activation marker CD40. Although both populations of DCs secreted IL-8 upon activation, the levels of IL-8 produced was several times higher within the M-DCs compared with the P-DCs population. Before activation, both subsets of DCs expressed the IL-8 receptor type B (CD128b); but after stimulation the IL-8 receptor was down-regulated in both populations of DCs. Increased expression of MHC class II molecules is generally regarded as an early activation marker of DCs. However, only the P-DCs showed a significant up-regulation of MHC class II after stimulation. The M-DC population up-regulated MHC class II without any prior activation; thus care should be taken using increased expression of MHC class II molecules as an early activation marker of peripheral M-DCs after activation in vitro. In conclusion, we propose that during activation of human DCs the production of IL-8 and loss of CD128b are the earliest signs of activation preceding both MHC class II, CD40, CD80, and CD86 expression.

Decreased production of inflammatory cytokines by circulating monocytes and dendritic cells in type 2 diabetic men with atherosclerotic complications

Antigen-presenting cells (APCs) are involved in the development of atherosclerosis, whose complications represent the main cause of death in diabetic patients. Nevertheless, their role in atherogenesis is poorly understood. We compared the number of circulating monocyte and dendritic cell (DC) subsets as well as their capacity to produce inflammatory cytokines IL-1beta, IL-6, and tumor necrosis factor-alpha (TNF-alpha) in type 2 diabetic men with (n=11) and without (n=44) chronic atherosclerotic complications. Identification and enumeration of peripheral blood (PB) lymphoid subsets, monocytes, myeloid (CD33strong+), CD16+, and plasmacytoid (CD33-/dim+) DCs as well as of their spontaneous and stimulated production of IL-1beta, IL-6, and TNF-alpha were performed at the single-cell level by flow cytometry. Our results show that type 2 diabetic men with atherosclerotic complications display a significantly reduced spontaneous secretion of IL-6 by monocytes and CD16+ DCs and of TNF-alpha by CD16+ DCs as compared to patients without atherosclerotic complications. Spontaneous secretion of IL-1beta by monocytes and CD16 DCs and of IL-6 by CD33+ and plasmacytoid DCs was detected in patients without atherosclerotic complications but not in the other patients with complications. Taken together, these results indicate that type 2 diabetic men with atherosclerotic complications display both quantitatively and functionally impaired immunological responses by circulating APCs. The decreased patterns of inflammatory cytokine production by these cells may influence the inflammatory response mediated by APCs as well as the antigen-specific responses mediated by other cells such as T cells.

Persistent abnormalities in peripheral blood dendritic cells and monocytes from HIV-1-positive patients after 1 year of antiretroviral therapy

Antiretroviral therapy (ART) has led to marked decreases in morbidity and mortality rates among HIV-1-positive patients; however, immune recovery is not complete. Although dendritic cells (DCs) were shown to be involved in HIV-1 pathogenesis, few studies have investigated the effect of ART on DCs. We have analyzed the effect of ART on numerical distribution, expression of chemokine receptors, and ex vivo production of inflammatory cytokines by peripheral blood (PB) monocytes and DCs in a cohort of chronically infected HIV-1-positive patients. Patients were tested before therapy and at weeks +2, +4, +8, +12, and +52 after starting ART.Our results show an incomplete T-cell immune reconstitution in chronically infected patients who had undetectable plasma viremia while taking ART for 1 year. This was associated with persistent abnormalities at week +52 of ART, corresponding to increased numbers of CD16 DCs and monocytes, as well as altered expression of CXC chemokine receptors, in the form of increased CXCR1 expression on monocytes and decreased reactivity for CXCR2 and/or CXCR4 on myeloid and plasmacytoid DCs. In addition, an abnormally high spontaneous ex vivo secretion of inflammatory cytokines by CD16 DCs and monocytes was still detected after 1 year of ART. These abnormalities were especially pronounced in patients with less than 200 CD4 T cells/microL, which could be related to the persistence of undetected viral replication and sustained immune activation.

Bortezomib induces selective depletion of alloreactive T lymphocytes and decreases the production of Th1 cytokines

We explored the ability of the proteasome inhibitor bortezomib, which prevents nuclear factor kappaB (NF-kappaB) activation, to block T-cell activation, proliferation, and survival within alloreactive compared with resting T cells. For this purpose, T cells were stimulated with PHA, alphaCD3/alphaCD28, or allogeneic dendritic cells or through mixed lymphocyte cultures. NF-kappaB expression increased in activated T lymphocytes compared with resting T cells. Of interest, the higher the NF-kappaB expression, the more intense the proliferative blockade induced by bortezomib. Moreover, after mixed lymphocyte reaction (MLR) cultures, alloreactive T cells were 2 logs more sensitive to bortezomib-induced apoptosis than the resting T-cell counterpart. This effect was due to a selective induction of apoptosis among activated T cells that was related to caspase activation and cleavage of the antiapoptotic bcl-2 protein and was partially abolished by the addition of the pancaspase inhibitor Z-VAD-FMK. In addition, after secondary MLR, the number of activated T cells was significantly reduced among T lymphocytes previously cultured with bortezomib when cells from the same donor were used as stimulating cells. By contrast, when third-party donor cells were used as stimulating cells, no significant differences were observed between T lymphocytes previously exposed or not to the drug, indicating a highly specific depletion of T lymphocytes alloreactive against primary donor antigens. The addition of bortezomib decreased not only the proliferation and viability of activated T lymphocytes but also the levels of IFNgamma and IL-2, which were significantly decreased among activated T cells cultured with bortezomib at doses ranging from 10 to 100 nM. In conclusion, at concentrations reached in the clinical setting, bortezomib induces selective apoptosis and decreases Th1 response among alloreactive T lymphocytes while it barely affects unstimulated T cells. These results establish the basis for the clinical use of bortezomib in the management of graft-versus-host disease (GVHD).

Fate of Chlamydophila pneumoniae in human monocyte-derived dendritic cells: Long lasting infection

Earlier studies from this group demonstrated that Chlamydophila pneumoniae co-localized with dendritic cells (DC) in temporal artery biopsies from patients with giant cell arteritis (GCA). To investigate the interaction of DC with C. pneumoniae we employed an in vitro cell culture system of human monocyte derived DC. These DC were infected with C. pneumoniae and observed at regular time intervals up to 25 days post infection. Chlamydiae were visualized inside DC by both confocal and electron microscopy. Statistical analysis showed an increase in the number of chlamydial antigen during that period (p < 0.00005, chi2-test). Titration of DC lysates on HEp-2 cells showed that infectious progeny was recovered at various intervals but showed no exponential growth. Additionally, RT-PCR analyses of infected DC identified transcripts from dnaA, ftsK and tal throughout a period of 14 days, indicating viable chlamydiae. Thus, human monocyte-derived DC are susceptible to C. pneumoniae infection. These results indicate that C. pneumoniae-infected DC can play an important role in the transmission of these bacteria in GCA and other chlamydial diseases.

Characterization of bone marrow T cells in monoclonal gammopathy of undetermined significance, multiple myeloma, and plasma cell leukemia demonstrates increased infiltration by cytotoxic/Th1 T cells demonstrating a squed TCR-Vβ repertoire

BACKGROUND

The majority of studies published to date regarding the role of the bone marrow (BM) microenvironment in the pathogenesis of monoclonal gammopathies (MG) have focused on the interaction between stroma cells and plasma cells, whereas information concerning the lymphocytes infiltrating the tumor microenvironment is scanty.

METHODS

The authors measured the distribution, TCR-Vbeta repertoire, immunophenotype, and functional characteristics of different subsets of BM T lymphocytes from 61 nontreated patients with MG (30 patients with MG of undetermined significance [MGUS], 27 patients with multiple myeloma [MM], and 4 patients with plasma cell leukemia [PCL]).

RESULTS

The authors found a significantly increased rate of BM infiltration by T cells in all patient groups, at the expense of CD4+CD8- and CD4-CD8- T lymphocytes and both CD4+CD28- and CD8+CD28- cytotoxic/effector T cell subsets, and associated with TCR-Vbeta expansions in both CD4+ and CD8+ BM T cells in the majority of patients with MGUS, MM, and PCL. Moreover, the percentage of T cells secreting interferon (IFN)-gamma was found to be increased (P < or = 0.05) both in CD4+ and CD8+ T cells in MGUS and MM patients, and a higher plasma concentration of IFN-gamma was found in patients with MM. It is interesting to note that a positive correlation was noted between the proportion of CD28- and both the percentage of IFN-gamma-secreting cells and the proportion of expanded TCR-Vbeta lymphocytes within the total BM CD4+ T cells.

CONCLUSIONS

The results of the current study demonstrated an increased infiltration of BM by T cells associated with frequent TCR-Vbeta expansions and a more prominent cytotoxic/Th1 phenotype in all the patient groups studied.

Maturation-associated immunophenotypic abnormalities in bone marrow B-lymphocytes in myelodysplastic syndromes

Recent studies concerning the pathophysiology of myelodysplastic syndromes (MDS) have shown evidences for the existence of complex interactions between hematopoietic stem cells and the bone marrow (BM) microenvironment. We analyzed the B-lymphocyte maturation in BM of patients with MDS. For this purpose, 41 newly-diagnosed patients were analyzed. Enumeration and characterization of CD34+ and CD34- B-cell precursors and mature B-lymphocytes was performed using multiparameter flow cytometry. BM from eight transplant donors and six orthopedic surgery patients were used as controls. CD34+/CD45(lo) B-cells were found in 17/22 patients with RA/RARS and in 5/13 with RAEB. In patients with RAEB-t and CMML no CD34+ B-cell precursors could be detected. A positive correlation was found between CD34+ and CD34- B-cell precursors (r=0.52). CD34+ B-cell precursors presented an inverse correlation with BM percentage of blasts and peripheral leukocytes and a positive one with hemoglobin. Asynchronous antigen expression (CD19+/CD79a- cells) was found in 7/11 cases of RA/RARS and 6/18 cases of RAEB in which this phenotype was examined. Abnormal patterns of expression for at least one antigen was found in 91% of RA/RARS cases and in 74% of RAEB. Underexpression of TdT and CD79a were the most frequent abnormalities. Our results present evidences of an abnormal B-cell maturation in MDS. This may be an evidence that B-lymphocytes are derived of the abnormal clone. But it may also be the consequence of influences of abnormalities of BM microenvironment leading to an impaired commitment and maturation of the B-cell line in MDS. Studies performed with purified well-characterized B-cells may further elucidate these abnormalities.

IL-12 Production by Human Monocyte-Derived Dendritic Cells

Dendritic cells (DCs) are under investigation as immunotherapeutic agents in the treatment of cancer and infectious diseases. One of the important factors in skewing the immune response toward clinically beneficial TH1-type immunity is interleukin-12p70. IL-12p70 is synthesized and secreted in response to inflammatory cytokines, bacterial/viral components, and CD40 ligation. This study investigated the production of IL-12 by DCs at the single-cell level using a sensitive intracellular cytokine flow cytometry-based assay system. The authors observed that immature DCs could be stimulated with several compounds to produce IL-12, but that IL-12 production was a feature of a minority of activated DCs. IL-12+ DCs were characterized as being partially matured (ie, absent or low CD83 expression, with variable expression of CD1a and CD64). Interestingly, activated DCs lacked expression of the CD16 and CD64 Fc gammaR, which may have important implications for exogenous antigen-loading strategies.

Long-term Immune Recovery of Patients Undergoing Allogeneic Stem Cell Transplantation: A Comparison with Their Respective Sibling Donors

We have addressed whether patients' immune system status after allogeneic stem cell transplantation, assessed more than 1 year after the procedure, recovers normal function as compared with that of their respective donors. An additional aim was to compare the status of the immune system between patients receiving reduced-intensity conditioning regimens and those undergoing myeloablative transplantations. For this purpose, we analyzed not only the different subsets of peripheral blood (PB) lymphocytes, but also circulating dendritic cell (DC) subpopulations, together with cytokine production by PB T cells, in a series of 38 patients undergoing allogeneic stem cell transplantation. We compared these patients with their respective HLA-matched donors by performing a simultaneous patient/donor paired study. Complete bone marrow chimerism status and normal PB cell counts were demonstrated in all recipients. The most relevant numeric differences found between patients and donors were related to the distribution of the distinct subsets of PB DCs (CD16+ DCs were increased, whereas myeloid and plasmacytoid DC subsets were decreased in the patient group). This was associated with an increased number of B cells, an inverted CD4/CD8 T-cell ratio, and a decrease in CD4+/CD8+ double-positive T cells in the patient group. In addition, a predominance of a T-helper 1 pattern of cytokine production (interferon gamma and tumor necrosis factor alpha) with decreased secretion of T-helper 2-associated cytokines (interleukin 5 and interleukin 10) was also observed at the single-cell level. No significant differences were found in any of the parameters analyzed between patients receiving reduced-intensity conditioning regimens and those undergoing myeloablative transplantations.

Characterization of human peritoneal dendritic cell precursors and their involvement in peritonitis

Scattered evidence suggests that the human peritoneal cavity contains cells of the dendritic cell (DC) lineage but their characterization is missing. Here, we report that the peritoneal cavity of normal subjects and of stable patients on peritoneal dialysis (PD) contains a population of CD14(+) cells that can differentiate into DCs or macrophages. Within this pool, we characterized a CD14(+)CD4(+) cell subset (2.2% of the peritoneal cells) fulfilling the definition of myeloid DC precursors or pre-DC1 cells. These cells expressed high levels of HLA-DR, CD13, CD33, and CD86, and low levels of CD40, CD80, CD83, CD123, CD209, TLR-2 and TLR-4. These cells retained CD14 expression until late stages of differentiation, despite concomitant up-regulation of DC-SIGN (CD209), CD1a, CD80 and CD40. Peritoneal pre-DC1 cells had endocytic capacity that was down-regulated upon LPS/IFN-gamma stimulation, were more potent allo-stimulators than peritoneal CD14(+)CD4(-/lo) cells and monocyte-derived macrophages, and induced Th1 cytokine responses. More importantly, the number of peritoneal pre-DC1 cells increased during PD-associated peritonitis, with a different profile for Gram positive and Gram negative peritonitis, suggesting that these cells participate in the induction of peritoneal adaptive immune responses, and may be responsible for the bias towards Th1 responses during peritonitis.

Minimal residual disease monitoring by flow cytometry

In patients with acute leukaemia, studies of minimal residual disease (MRD) provide powerful and independent prognostic information. Multiparameter flow cytometry is a widely applicable and reliable approach for monitoring MRD. Using triple or quadruple marker combinations, aberrant or uncommon phenotypic profiles can be identified in about 80% of patients with acute myeloid leukaemia (AML) and 95% of patients with acute lymphoblastic leukaemia (ALL). These profiles can reveal leukaemic cells even when these are not evident by morphological analysis. Thus, one leukaemic cell among 1000-10000 normal bone marrow or peripheral blood cells can be routinely detected. In this chapter we discuss technical aspects of MRD detection by flow cytometry and summarize results of correlative studies between MRD, clinical and biological features of leukaemia and treatment outcome. Current knowledge indicates that MRD studies using well-tested methodologies are clinically useful and should be incorporated into the clinical management of patients with acute leukaemia.

CD87 (urokinase-type plasminogen activator receptor), function and pathology in hematological disorders: a review

The analysis of CD87 (urokinase-type plasminogen activator receptor - uPAR) expression has a potential role in the diagnostic or prognostic work-up of several hematological malignancies, particularly acute leukemia and multiple myeloma. The distribution of CD87 in acute myeloid leukemia (AML) varies according to the FAB subtype (highest expression in M5 and lowest in M0). Functionally, it is conceivable that the expression of CD87 could contribute to the invasive properties of the leukemic cells towards the skin and mucosal tissues as reflected by the clinical behavior of CD87 high cases. The lack of or weaker expression of CD87 on blast cells from ALL patients supports the concept that CD87 investigation might help in the distinction of AMLs from lymphoid malignancies. Among lymphoproliferative disorders, the expression of CD87 is exclusively found in pathological plasma cells. Since plasma cells also coexpress some adhesion molecules such as CD138 and CD56, this observation is consistent with the capacity of these cells to home in the bone compartment. High levels of soluble uPAR appear to represent an independent factor predicting worse prognosis and extramedullary involvement in multiple myeloma.

Immunophenotypic and Functional Characterization of Cord Blood Dendritic Cells

Dendritic cells (DCs) play a pivotal role in the activation of T cells, which are effector cells in graft-versus-host disease (GVHD). A low incidence of GVHD following cord blood (CB) transplantation has long been reported; despite this, little information is currently available on the characteristics of CB DCs. The goal of the present study was to investigate the immunophenotypic characteristics and distribution of CB DCs and their subsets. For that purpose we have analyzed 15 CB samples as compared to normal peripheral blood (PB) (n = 7) and blood from patients submitted to an allogeneic PB stem cell transplantation (allo-PBSCT) (n = 6). Our results show an overall decreased frequency of DCs in CB due to the presence of significantly lower numbers of CD123inter./CD33inter./CD16+ DCs. Phenotypically, CB DCs displayed a tendency to express lower levels of the gamma-chain interleukin-2 (IL-2) receptor (CD132) and of the CD86 co-stimulatory molecule, supporting a higher degree of immaturity for CB as compared to PB DCs. After activation of CB DCs with lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma) higher frequencies of cytokine-producing cells were found among CD123inter./CD33inter./CD16+ and CD123dim/CD33bright/CD16- DCs; however, when only the cytokine-producing DCs were considered, a significant decrease in the amount of different cytokine (e.g., IL-1beta and IL-6) produced per cell was observed especially for CD16+ CB DCs. These findings support a higher degree of immaturity for CB as compared to PB DCs that might contribute to explain, at least in part, the low incidence and severity of GVHD observed after CB transplantation.

Altered maturation of peripheral blood dendritic cells in patients with breast cancer

Tumours have at least two mechanisms that can alter dendritic cell (DC) maturation and function. The first affects the ability of haematopoietic progenitors to differentiate into functional DCs; the second affects their differentiation from CD14+ monocytes, promoting an early but dysfunctional maturation. The aim of this study was to evaluate the in vivo relevance of these pathways in breast cancer patients. For this purpose, 53 patients with invasive breast cancer were compared to 68 healthy controls. To avoid isolation or culture procedures for enrichment of DCs, analyses were directly performed by flow cytometry on whole-blood samples. The expression of surface antigens and intracellular accumulation of regulatory cytokines upon LPS stimulation were evaluated. The number of DCs, and in particular of the myeloid subpopulation, was markedly reduced in cancer patients (P<0.001). Patient DCs were characterized by a more mature phenotype compared with controls (P=0.016), and had impaired production of IL-12 (P<0.001). These alterations were reverted by surgical resection of the tumour. To investigate the possible role of some tumour-related immunoactive soluble factors, we measured the plasmatic levels of vascular endothelial growth factor, IL-10 and spermine. A significant inverse correlation between spermine concentration and the percentage of DCs expressing IL-12 was found. Evidence was also obtained that in vitro exposure of monocyte-derived DCs to spermine promoted their activation and maturation, and impaired their function. Taken together, our results suggest that both the above-described mechanisms could concomitantly act in breast cancer to affect DC differentiation, and that spermine could be a mediator of dysfunctional maturation of DCs.

Dendritic cell subsets in blood and lymphoid tissue of rhesus monkeys and their mobilization with Flt3 ligand

We provide phenotypic and functional evidence of premonocytoid dendritic cells (DCs) and preplasmacytoid DCs in blood and of corresponding DC subsets in secondary lymphoid tissue of rhesus monkeys. Subsets were identified and sorted by 4-color flow cytometry using antihuman monoclonal antibodies cross-reactive with rhesus monkey. To mobilize pre-DC subsets, fms-like tyrosine 3 kinase ligand (Flt3L; 100 microg/kg subcutaneously) was administered for 10 days. Presumptive pre-DC subsets were identified within the lineage- (Lin-) major histocompatibility complex (MHC) class II+ fraction of blood mononuclear cells. Premonocytoid DCs were CD11c+CD123- (interleukin-3Ralpha- [IL-3Ralpha-]). Preplasmacytoid DCs were characterized as CD11c-CD123++ Flt3L increased the CD11c+ pre-DC (7-fold) and CD123++ pre-DC subsets (3-fold) in blood. The freshly isolated CD11c+ pre-DC subset induced modest proliferation of naive allogeneic T cells. After overnight culture with granulocyte macro-phage-colony-stimulating factor (GMCSF) and CD40L, both subsets up-regulated surface costimulatory molecules, and CD11c+ pre-DCs became potent allostimulators. Freshly isolated CD123++ pre-DCs showed typical plasmacytoid morphology and, when cultured with IL-3 and CD40L for 72 hours, developed mature DC morphology. Following stimulation with CD40L, CD11c+ pre-DCs secreted increased levels of IL-12p40. Importantly, herpes simplex virus-stimulated CD123++ pre-DCs, but not CD11c+ pre-DCs, secreted interferon-alpha (IFN-alpha). Corresponding DC subsets were identified by flow analysis and immunohistochemistry in lymph nodes wherein both populations were increased 2- to 3-fold by Flt3L administration. CD123+ pre-DCs produced IFN-alpha in response to in vivo viral infection. Thus, rhesus monkeys exhibit 2 distinct DC precursor populations that closely resemble those of humans. Both are mobilized into blood and lymphoid tissue by Flt3L, offering potential for their further characterization and possible therapeutic application.

TCRalphabeta+/CD4+ large granular lymphocytosis: a new clonal T-cell lymphoproliferative disorder

Large granular lymphocyte (LGL) leukemia is a well-recognized disease of mature T-CD8(+) or less frequently natural killer cells; in contrast, monoclonal expansions of CD4(+) T-LGL have only been sporadically reported in the literature. In the present article we have explored throughout a period of 56 months the incidence of monoclonal expansions of CD4(+) T-LGL in a population of 2.2 million inhabitants and analyzed the immunophenotype and the pattern of cytokine production of clonal CD4(+) T cells of a series of 34 consecutive cases. Like CD8(+) T-LGL leukemias, CD4(+) T-LGL leukemia patients have an indolent disease; however, in contrast to CD8(+) T-LGL leukemias, they do not show cytopenias and autoimmune phenomena and they frequently have associated neoplasias, which is usually determining the clinical course of the disease. Monoclonal CD4(+) T-LGLshowed expression of TCRalphabeta, variable levels of CD8 (CD8(-/+dim)) and a homogeneous typical cytotoxic (granzyme B(+), CD56(+), CD57(+), CD11b(+/-)) and activated/memory T cell (CD2(+bright), CD7(-/+dim), CD11a(+bright), CD28(-), CD62L(-) HLA-DR(+)) immunophenotype. In addition, they exhibited a Th1 pattern of cytokine production [interferon-gamma(++), tumor necrosis factor-alpha(++), interleukin (IL-2)(-/+), IL-4(-), IL-10(-), IL-13(-)]. Phenotypic analysis of the TCR-Vbeta repertoire revealed large monoclonal TCR-Vbeta expansions; only a restricted number of TCR-Vbeta families were represented in the 34 cases analyzed. These findings suggest that monoclonal TCRalphabeta(+)/CD4(+)/NKa(+)/CD8(-/+dim) T-LGL represent a subgroup of monoclonal LGL lymphoproliferative disorders different from both CD8(+) T-LGL and natural killer cell-type LGL leukemias. Longer follow-up periods are necessary to determine the exact significance of this clonal disorder.

Differences in circulating dendritic cell subtypes in cord blood and peripheral blood of healthy and allergic children

BACKGROUND

Different types of circulating dendritic cells have been described. Dendritic cells influence differentiation of naive T lymphocytes into T helper type 1 (Th1) and Th2 effector cells.

OBJECTIVE

The purpose of this study was to evaluate the number of circulating DC subtypes in peripheral blood of allergic and healthy children and in cord blood of neonates from allergic and non-allergic parents.

METHODS

Circulating dendritic cells were flow cytometrically identified in whole blood samples as lineage (CD3, CD14, CD16, CD19, CD20, CD56) negative, CD34 negative and HLA-DR-positive cells. According to the expression of CD123 and CD11c, different DC subtypes were identified.

RESULTS

Apart from DC1 (CD11c+ CD123dim+) and DC2 (CD11c- CD123high+), a third DC population was described with less differentiated phenotypic characteristics, namely CD11c- CD123dim+, and therefore defined here as less differentiated DC (ldDC). These ldDC represented the major DC population in cord blood and showed an age-depended decrease. The highest level of ldDC was detected in children with atopic dermatitis, whereas asthmatic children showed the lowest ldDC counts. Furthermore, high-dose inhaled corticosteroid treatment in asthmatic children was related to a decreased ldDC number. The number of circulating DC2 was significantly lower in allergic children, especially in asthmatics, compared to healthy children. In cord blood, no differences in DC subtypes were detectable between neonates at low and high risk for allergic disorders.

CONCLUSION

These results indicate that, apart from DC1 and DC2, a third population of dendritic cells, identified as CD11c- CD123dim+ cells and defined as less differentiated DC, must be considered in the evaluation of circulating DC. Furthermore, DC2 counts were decreased in allergic children, especially in asthmatics, which might be the consequence of an increased recruitment to the target organs.

Characterization of human blood dendritic cell subsets

Dendritic cells (DCs) are key antigen-presenting cells for stimulating immune responses and they are now being investigated in clinical settings. Although defined as lineage-negative (Lin(-)) HLA-DR(+) cells, significant heterogeneity in these preparations is apparent, particularly in regard to the inclusion or exclusion of CD14(+), CD16(+), and CD2(+) cells. This study used flow cytometry and a panel of monoclonal antibodies (mAbs), including reagents from the 7th Leukocyte Differentiation Antigen Workshop, to define the cellular composition of 2 standardized peripheral blood mononuclear cell (PBMCs)-derived Lin(-) HLA-DR(+) preparations. Lin(-) cells were prepared from PBMCs by depletion with CD3, CD14, CD19, CD11b, and either CD16 or CD56 mAbs. Analysis of the CD16-replete preparations divided the Lin(-) HLA-DR(+) population into 5 nonoverlapping subsets (mean +/- 1 SD): CD123 (mean = 18.3% +/- 9.7%), CD1b/c (18.6% +/- 7.6%), CD16 (49.6% +/- 8.5%), BDCA-3 (2.7% +/- 1.4%), and CD34 (5.0% +/- 2.4%). The 5 subsets had distinct phenotypes when compared with each other, monocytes, and monocyte-derived DCs (MoDCs). The CD85 family, C-type lectins, costimulatory molecules, and differentiation/activation molecules were also expressed differentially on the 5 Lin(-) HLA-DR(+) subsets, monocytes, and MoDCs. The poor viability of CD123(+) DCs in vitro was confirmed, but the CD16(+) CD11c(+) DC subset also survived poorly. Finally, the individual subsets used as stimulators in allogeneic mixed leukocyte reactions were ranked by their allostimulatory capacity as CD1b/c > CD16 > BDCA-3 > CD123 > CD34. These data provide an opportunity to standardize the DC populations used for future molecular, functional and possibly even therapeutic studies.