Total Number Of Dendritic Cells Research Articles

A Landscape of Dendritic Cells Development, Activation and Migration in Mouse Model of Sickle Cell Anemia

Dendritic cells (DCs) are crucial players of innate immunity in initiating, polarizing, and regulating the adaptive immune response. They become activated upon encountering either pathogen- or damage-associated molecular patterns (PAMPs or DAMPs), which are often released due to tissue necrosis or intravascular hemolysis, common events in individuals with sickle cell disease (SCD), one of the most common hemoglobinophaties that affects millions of people worldwide. Upon activation, DCs migrate to peripheral lymph nodes, where they present antigens to T lymphocyte together with co-stimulatory or inhibitory molecules. In addition, they can polarize T cell response by releasing pro- or anti-inflammatory cytokines. We previously showed that SCD patients have higher circulating total and inflammatory DCs, whereas the ratio of type 1 conventional DCs (cDC1) is lower than control individuals. These changes correlated with number of reticulocytes and with the skewed T response towards Th17. Alterations in the development and activation of DC subpopulations, as well as in their function can impair the immune response or tolerance, which may account for the dysfunction in T lymphocyte responses observed in SCD patients. In order to investigate the development, activation and migration of DCs during SCD, we characterized these cells by flow cytometry in lymphoid organs of Townes mice, which have human S hemoglobin (HbS). Our data show that Townes mice (SS) have lower number of total DCs in bone marrow (p=0.057; N=8 each), however, they have higher number of these cells in the spleen (p<0.0001; N=8 each) and lymph nodes (p<0.0021; N=8 each) when compared with the littermate WT mice, suggesting migration of DCs to these peripheral organs. Evaluation of the ratios of DCs subsets shows that the frequency of cDC1 (CD11c +CD8a +CD11b -) among total DCs is higher in the three organs of SS mice compared with WT mice (p=0.004 in spleen; p=0.0015 in bone marrow; and p=0.01 in lymph nodes; N=8 each group). In contrast, the percentage of type 2 conventional DCs, cDC2 (CD11c +CD8a -CD11b +) is similar or lower in SS mice than WT mice (p=0.0005 in spleen; N=8 each). In addition, the frequency of plasmacytoid dendritic cell, pDC (CD11c +B220 +SiglecH +) is higher in lymph nodes (p=0.0006; N=8 each) and lower in bone marrow (p=0.0017; N=8 each) of SS mice when compared with WT mice, indicating that the migration of DCs to peripheral organs is due to cDC1 and pDC. Regarding their maturation and activation phenotype, cDC1 and cDC2 from SS mice have a more immature or inhibitory phenotype than WT mice, as showed by MHC-II (cDC1: p=0.01 in spleen; p=0.0004 in lymph nodes; N=8 each) and CD86 expression (cDC1: p=0.013 in spleen; p=0.0003 in bone marrow; and p= 0.03 in lymph nodes; cDC2: p=0.0067 in bone marrow and p=0.038 in lymph nodes; N=8 each). On the other hand, pDCs from the three organs of SS mice showed a more mature profile than WT mice, as demonstrated by an increase in Sca-1 expression (p=0.0024 in spleen; p=0.037 in bone marrow; and p=0.04 in lymph nodes; N=8 each), indicating that cDCs are being inhibited whereas pDCs are activated during SCD even in steady state. Aimed to understand whether at least part of the alterations on DCs is due to changes in their development, we quantified monocyte and DC progenitor, MDP (Lin -(CD3/CD19/CD56/CD14) CD135 +CD11c -CD115 +CD117 +) and common DC progenitor, CDP (Lin -CD135 +CD11c -CD115 +CD117 -) in bone barrow. Our data show that the ratio of MDP, the earlier progenitor, is increased (p=0.0009; N=8 each), whereas CDP, the progenitor committed to DCs, is diminished (p=0.014; N=8 each) in SS mice when compared with WT mice, indicating a change in the DC compartment in SS mice since their developmental stage. When we performed an in vitro differentiation of DC from bone marrow cells in the presence of flt3l, we did not observe statistical difference in either development and apoptosis of DCs, or in the percentages of DC subsets between SS and WT mice, indicating that the alteration in DC development in SS mice may be due to environmental conditions instead of CDP or DC intrinsic factor. Our findings so far improve our understanding of DCs dynamics in SCD, including the development, activation and migration of the different subsets that may have an important impact on adaptive immune response disfunction in SCD, which may account for the chronic inflammatory state and the susceptibility to infections.

427.1: Donor Dendritic Cell Depletion Allows Novel Insights Into the Alloimmune Response Following Murine Composite Tissue and Skin Transplantation

Background: Cell-based therapies in vascularized composite tissue allotransplantation (VCA) have demonstrated promising results with the potential to modify life-long conventional immunosuppression. Dendritic cells (DCs) promote pro-inflammatory, alloimmune responses. Of particular interest is the role of DCs as antigen-presenting cells and potential tolerogenic effects as immature DCs. Material and Methods: Diphteria Toxin Receptor (DTR) transgenic or wild-type (WT) donor mice were used to deplete subsets of DCs or APCs respectively in a fully histoincompatible murine hind limb and skin transplant models; prior to procurement, all donors were either treated with diphteria toxin (DT; at -15 hours) or with clodronate (CL; 8 days prior to Tx). DBA/2J mice served as recipients. Study endpoint was on POD 6. Alloimmune response was assessed sequentially; graft survival, intragraft structural and inflammatory changes were tested serially. Results: The total number of dendritic cells (CD11b- CD11c+ DC) had markedly increased in recipients of skin WT grafts compared to recipients of VCA WT grafts (p<0.0001). The treatment with CL or DT significantly reduced the numbers of maturated and activated DC in the spleen, blood, and LN of mice receiving a skin graft, whereas numbers of CD11b-CD11c+MHCII+ and CD11b-CD11c+CD40+ DC were exclusively reduced in the spleen of VCA recipients after donor pretreatment with DT. cDC 1 subtypes were significantly higher in VCA WT vs. skin WT recipients (p<0.001). Donor pretreatment with DT decreased cDC1 counts only in recipients of VCA grafts (p<0.001).Luminex analysis revealed significantly higher TNF-alpha serum levels in the VCA WT vs. skin WT group (p<0.01). TNF-beta serum levels were significantly decreased in VCA depletion groups vs VCA WT group (p<0.001). Clinical signs of acute rejection among the VCA groups revealed higher rejection grades in the WT compared to the DC depletion group according to the BANFF criteria (grade III vs. grade II). Additional injection of immature DCs did not show any difference in allograft survival (p=ns).Conclusion: This is to our knowledge the first systematic study delineating the role of mature and immature DCs tested across and skin transplants. Those data may help explaining split-tolerance phenomenon in VCA while providing a basic concept for the utilization of mature and immature DCs in modifying alloimmune responses in VCA transplants.

ИММУНОЛОГИЧЕСКИЕ ПРЕДИКТОРЫ ОТТОРЖЕНИЯ ПОЧЕЧНОГО ТРАНСПЛАНТАТА В РАННЕМ ПОСЛЕОПЕРАЦИОННОМ ПЕРИОДЕ

Objective. To determine the immunological predictors of renal graft rejection in the early postoperative period. Methods. Three groups were formed out of the 197 renal graft recipients. The group PGF (n=101) was made up of patients with satisfactory primary graft function. The group PGD (n = 82) included patients with primary graft dysfunction without episodes of rejection. The group RGR (n=14) consisted of patients with primary dysfunction and renal graft rejection. On the 7&lt;sup&gt;th&lt;/sup&gt; day after transplantation the early kidney graft function was assessed on the basis ofserum creatinine levels. When the serum creatinine value was lower than 300 μmol/L the function was considered to be primary, at a creatinine concentration was equal to or higher than 300 μmol/L, as well as in the case of needfor maintenance dialysis on the first week after transplantation, the state was classified as the renal graft dysfunction. In the early postoperative period, the number of LIN-HLA-DR+ dendritic cells with the LIN-HLA-DR+CD11c+CD123- and LIN-HLA-DR+CD11c-CD123+ phenotypes in the fluid from the drainage installed to the kidney graft during surgery was determined. Predictive characteristics of the mDC and pDC levels in the drainage fluid were determined to predict renal graft rejection, and diagnostic capability of this indicator were identified. Results. It has been revealed that renal graft rejection is characterized by a significant growth of the total number of dendritic cells in the drainage fluid, mainly due to myeloid ones. Predictive characteristics were determined by the level of myeloid and plasmacytoid dendritic cells in the drainage fluid. The cut-off point of the level of myeloid dendritic cells was determined at the level of 60.32%, and for plasmacytoid dendritic cells it corresponded to 39.68%. Conclusion. With the level of myeloid dendritic cells in the drainage fluid greater or equal 60.32%, and plasmacytoid cells lower or equal 39.68%, renal graft rejection is predicted with a sensitivity of 99% and 93%, respectively, and a specificity of 89% and 91%, respectively. What this paper adds The level of dendritic cells and their subpopulations in the drainage fluid in renal graft recipients has been firstly studied. It has been established that acute renal graft rejection is associated with a high concentration of the total number of dendritic cells in the drainage fluid. More over this increase occurs mainly due to myeloid dendritic cells. The determination of the level of myeloid and plasmacytoid dendritic cells in the drainage fluid can be used as a predictor of renal graft rejection.

IL-33 receptor (ST2) deficiency downregulates myeloid precursors, inflammatory NK and dendritic cells in early phase of sepsis

BackgroundSepsis is a life-threatening disease mediated by profound disturbances in systemic inflammatory response to infection. IL-33 is multifunctional regulator of numerous aspects of innate and adaptive immune response. The aim of this article was to further evaluate the role of IL-33 receptor (ST2) in different pathways of innate immunity during early polymicrobial sepsis.MethodsPolymicrobial sepsis was induced using cecal ligation and puncture (CLP) model in ST2 deficient (ST2−/−) and wild type BALB/c mice. Peritoneal and spleen cells were isolated for further phenotyping. Apoptosis was determined by immunohistochemistry and flow cytometry.ResultsDeletion of ST2 leads to increased susceptibility to early manifestations of sepsis as evaluated by clinical signs and survival. These are accompanied by decrease in the total number of neutrophils, eosinophils and mast cells in peritoneal cavity 12 h after CLP. In early sepsis there was also low number of precursors of myeloid cells in particular CD11b+Ly6G+Ly6Clow cells in spleen of ST2−/− mice. Although the number of NK cells in the spleen was similar, there were significant differences in the presence of inflammatory IFN-γ and IL-17 producing NK cells. Further, ST2 deletion affects the phenotype and maturation of dendritic cell in sepsis. The total number of dendritic cells in the spleen was lower as well as IL-12 expressing dendritic cells. Finally, there was higher frequency of active caspase-3 positive and early apoptotic cells, in particular CD11c positive cells, in spleen of septic ST2−/− mice.ConclusionTaken together, our data provide the evidence that ST2 deficiency in early phase of sepsis downregulates myeloid precursors, inflammatory NK and dendritic cells.

Mucosal biopsy shows immunologic changes of the colon in patients with early MS.

Objective:To investigate immune cells of the colonic mucosa and fecal short-chain fatty acids (SCFAs) in treatment-naive patients with a clinically isolated syndrome (CIS) or early relapsing MS.Methods:In this cross-sectional proof-of-concept study, we obtained mucosal specimens during ileocolonoscopy from 15 untreated patients with CIS/MS and 10 controls. Mucosal immune cells were analyzed by FACS, and gas chromatography-mass spectrometry measurements of stool samples served to determine SCFA.Results:The number of total dendritic cells (DCs), CD103+ tolerogenic DCs, and CD4+25+127–regulatory T cells (Tregs) was significantly reduced in the distal colon of patients with CIS/MS compared with controls, whereas we found no differences in the proximal colon. The patients' fecal samples also showed a substantially lower content of SCFA and especially lower levels of butyrate and acetate.Conclusions:Our findings indicate a disturbed homeostasis of colonic DCs and Tregs in patients with MS which could be associated with colonic SCFA depletion. Although not implying causality, these findings confirm parallel abnormalities of the gut in MS and warrant further research if modulation of the colonic SCFA profile or the colonic Treg pool can serve to modify the course of MS.

Dendritic cells inversely regulate airway inflammation in cigarette smoke-exposed mice.

The recruitment and activation of inflammatory cells into the respiratory system is considered a crucial feature in the pathophysiology of chronic obstructive pulmonary disease (COPD). Because dendritic cells (DCs) have a pivotal role in the onset and regulation of immune responses, we investigated the effect of modulating DC subsets on airway inflammation by acute cigarette smoke (CS) exposure. CS-exposed mice (5 days) were treated with fms-like tyrosine kinase 3 ligand (Flt3L) and 120g8 antibody to increase total DC numbers and deplete plasmacytoid DCs (pDCs), respectively. Flt3L treatment decreased the number of inflammatory cells in the bronchoalveolar lavage (BALF) of the smoke-exposed mice and increased these in lung tissue. DC modulation reduced IL-17 and increased IL-10 levels, which may be responsible for the suppression of the BALF cells. Furthermore, depletion of pDCs led to increased infiltration of alveolar macrophages while restricting the presence of CD103(+) DCs. This study suggests that DC subsets may differentially and compartment-dependent influence the inflammation induced by CS. pDC may play a role in preventing the pathogenesis of CS by inhibiting the alveolar macrophage migration to lung and increasing CD103(+) DCs at inflammatory sites to avoid extensive lung tissue damage.

Intradermal administration of the Type II heat-labile enterotoxins LT-IIb and LT-IIc of enterotoxigenic Escherichia coli enhances humoral and CD8+ T cell immunity to a co-administered antigen.

Vaccinations are extremely effective at combating infectious diseases. Many conserved antigen (Ag) targets, however, are poorly immunogenic. Protein subunit vaccines frequently elicit only humoral immune responses and fail to confer protection against serious intracellular pathogens. These barriers to vaccine development are often overcome by the use of appropriate adjuvants. Heat-labile enterotoxins (HLT) produced by enterotoxigenic strains of Escherichia coli are potent adjuvants when administered by mucosal or systemic routes. The efficacy of the type II HLT, however, has not been well-defined when administered by the intradermal (ID) route. Using a murine ID immunization model, the adjuvant properties of LT-IIb and LT-IIc, two type II HLTs, were compared with those of LT-I, a prototypical type I HLT. While all three HLT adjuvants enhanced Ag-specific humoral responses to similar levels, LT-IIb and LT-IIc, in contrast to LT-I, induced a more vigorous Ag-specific CD8+ T cell response and proffered faster clearance of Listeria monocytogenes in a challenge model. Additionally, LT-IIb and LT-IIc induced distinct differences in the profiles of the Ag-specific CD8+ T cell responses. While LT-IIc stimulated a robust and rapid primary CD8+ T cell response, LT-IIb exhibited slower CD8+ T cell expansion and contraction kinetics with the formation of higher percentages of effector memory cells. In comparison to LT-I and LT-IIc, LT-IIb evoked better long-term protection after immunization. Furthermore, LT-IIb and LT-IIc enhanced the total number of dendritic cells (DC) in the draining lymph node (DLN) and expression of costimulatory molecules CD80, CD86, and CD40 on DCs. In contrast to LT-I, LT-IIb and LT-IIc induced less edema, cellular infiltrates, and general inflammation at the site of ID injection. Thus, LT-IIb and LT-IIc are attractive comprehensive ID adjuvants with unique characteristic that enhance humoral and cellular immunity to a co-administered protein Ag.

Changes in dendritic cells and dendritic cell subpopulations in peripheral blood of recipients during acute rejection after kidney transplantation

Background Advances in transplantation immunology show that the balance between dendritic cells (DCs) and their subsets can maintain stable immune status in the induction of tolerance after transplantation. The aim of this study was to investigate if DCs and DC subpopulations in recipient peripheral blood are effective diagnostic indicators of acute rejection following kidney transplantation. Methods Immunofluorescent flow cytometry was used to classify white blood cells (WBCs), the levels of mononuclear cells and DCs (including the dominant subpopulations, plasmacytoid DC (pDC) and myeloid DC (mDC)) in peripheral blood at 0, 1, 7, and 28 days and 1 year after kidney transplantation in 33 patients. In addition, the blood levels of interleukin-10 (IL-10) and IL-12 were monitored before and after surgery. Fifteen healthy volunteers served as normal controls. Patients were undertaking hemodialysis owing to uremia before surgery. Results The total number of DCs, pDC, and mDC in peripheral blood and the pDC/mDC ratio were significantly lower in patients than controls (P &lt;0.05). Peripheral DCs suddenly decreased at the end of day 1, then gradually increased through day 28 but remained below normal levels. After 1 year, levels were higher than before surgery but lower than normal. The mDC levels were higher in patients with acute rejection before and 1 day after surgery (P &lt;0.005). There was no significant difference in IL-10 and IL-12 levels between patients with and without acute rejection. Conclusion The changes in DCs and DC subpopulations during the acute rejection period may serve as effective markers and referral indices for monitoring the immune state, and predicting rejection and reasonably adjusting immunosuppressants.

Lack of Preoperative Enteral Nutrition Reduces Gut-Associated Lymphoid Cell Numbers in Colon Cancer Patients

To examine preoperative dietary influences on gut-associated lymphoid tissue (GALT) cell number in the context of postoperative infectious complications. There is little clinical evidence regarding whether nutritional routes affect GALT size and/or phenotype. The influence of GALT atrophy on clinical outcomes is also unclear. Patients with complete obstruction of the colon due to a tumor were excluded from this study. Study 1. Resected terminal ileum specimens, from 62 patients [preoperative parenteral nutrition (PN): n = 15, preoperative oral feeding (OF): n = 47] who underwent right colectomy during the period from 1997 to 2004 at our department, were immunohistochemically stained for counting numbers of T, IgA-producing, and mature and immature dendritic cells (DCs) in the lamina propria (LP) and intraepithelial space.Study 2. We reviewed 341 patients (PN: n = 99, OF: n = 242) with colon cancer who underwent colectomy during this period for postoperative complications. Study 1. T cell numbers in the LP and intraepithelial space and IgA-producing cell number in the LP were significantly lower in the PN than in the OF group. Mature DC number in the LP was significantly lower in the PN than in the OF group, whereas total DC numbers (both mature and immature DC) were similar in the 2 groups.Study 2. The PN group had significantly higher rates of total infectious complications, surgical site infection, pneumonia, infectious colitis, and central venous catheter infection. Lack of enteral delivery of nutrients reduces numbers of T and IgA-producing cells, as well as mature DCs, in GALT of colon cancer patients, as it does in animal models. A close association between GALT changes and infectious complication morbidity was confirmed.

Numerical defect of circulating dendritic cell subsets and defective dendritic cell generation from monocytes of patients with advanced melanoma

The behaviour of circulating dendritic cells (DCs) and DC generation from monocytes in melanoma patients during the progression of disease have not been described.We report a significant decrease in the absolute number of total DCs, which mainly affects plasmacytoid DCs in stage IV. Additionally, monocyte-DC generation is less efficient in advanced stages, resulting in DCs that exhibit increased phagocytic capacity, potentially indicating a less mature state. These findings elucidate aspects of basic tumour-mediated immunosuppression, which may have implications for immunotherapeutic approaches, suggesting that the selection of patients for immunotherapy should also be made on the basis of their immune status.

Subsequent gene expression pattern in dendritic cells following multiple trauma

Major trauma initiates a systemic inflammatory response, which is characterized by systemic release of various chemokines. There is growing evidence for the extraordinary role of dendritic cells (DC) as professional antigen-presenting cells and activators of the immune response. Recently, the impact of severe trauma on DC transcriptomic activation was demonstrated. The purpose of the present study was to evaluate gene expression pattern in DC following multiple trauma to gain further understanding of the mechanisms of posttraumatic immune response. Ten patients with multiple injuries aged 20 to 46years (mean 30 ± 9.2years) were included in this study. The mean injury severity score (ISS) was 36 ± 10.4 points. Repeated blood samples were taken on the day of admission (day 0) and on five consecutive days (day 1 to day 5). Microarray analysis and RT-qPCR were performed in primary isolated DC. A mean of 116,000 ± 21,466DC with a purity of 96 ± 0,8% were harvested. Gene expression of CCL5 and CXCL5 as well as TIMP1 and GUCY1B3 showed a significant increase within the first 4days after trauma. The time-dependent increase of these genes correlated significantly with serum CRP concentration and the total number of DC but neither with age nor with injury severity. Our study provides new data regarding temporal expression patterns of CCL5, CXCL5, TIMP1, and GUCY13B in multiple trauma. DC activation following trauma may follow a uniform pattern early after admission, eventually leading to cell recruitment.

Changes of dendritic cells in tumor-free, micrometastasis and tumor-containing lymph nodes from patients with breast cancer

Objective To investigate the changes of dendritic cells (DC) in tumor-free,microme-tastasis and tumor-containing lymph nodes from patients with breast cancer.Methods ( 1 ) Micrometastases in 477 pathologically negative lymph nodes from 53 cases of patients with breast cancer were assessed by using immunohistochemistry with cytokeratin-19 antibody.According to the results,the lymph nodes from 53 cases of patients with breast cancer were divided into tumor-free,micrometastasis and tumor-containing lymph nodes; (2) The number of DC in tumor-free,micrometastasis and tumor-containing lymph nodes was assessed by using immunohistochemistry with S-100 antibody,CDla antibody and CD83 antibody respectively.Results Thirty-six of 477 pathologically negative lymph nodes were detected with microme-tastasis.The number of S-100 positive DCs in micro-metastasis and tumor-containing lymph nodes was significantly less than that in tumor-free lymph nodes ( both P ＜0.01 ).There was no significant difference in the number of CDla positive DCs in tumor-free,micrometastasis and tumor-containing lymph nodes (P＞0.05 ).The number of CD83 positive DCs in micro-metastasis lymph nodes was significantly more than that in tumor-free lymph nodes (P ＜ 0.01 ).Conclusion When patients with breast cancer have metastasis in regional lymph nodes,the total number of DC in those lymph nodes would be decreased,resulting in local anti-tumor immunity declined.But at micrometastatic stage of lymph nodes,the number of mature DC is increased relatively with local anti-tumor immunity declined gently. Key words: Breast carcinoma; Micrometastasis ; Lymph nodes; Dendritic cells

Immunological Effect of Active Hexose Correlated Compound (AHCC) in Healthy Volunteers: A Double-Blind, Placebo-Controlled Trial

The aim of this study was to evaluate the effects of active hexose correlated compound (AHCC) intake on immune responses by investigating the number and function of circulating dendritic cells (DCs) in healthy volunteers. Twenty-one healthy volunteers were randomized to receive placebo or AHCC at 3.0 g/day for 4 wk. The number of circulating cluster of differentiation (CD)11c+ DCs (DC1) and CD11c− DCs (DC2) were measured. Allogeneic mixed-leukocyte reaction (MLR) was performed. Natural killer (NK) cell activity and the proliferative response of T lymphocytes toward mitogen (phytohemagglutinin [PHA]) were measured. We also measured cytokine production stimulated by lipopolysaccharide [interleukin (IL)-2, IL-4, IL-6, IL-10, interferon gamma-γ, tumor necrosis factor-α). The AHCC group (n = 10) after AHCC intake had a significantly higher number of total DCs compared to that at baseline and values from control subjects (n = 11). The number of DC1s in the AHCC group after intake was significantly higher than at baseline. DC2s in the AHCC group were significantly increased in comparison with controls. The MLR in the AHCC group was significantly increased compared to controls. No significant differences in PHA, NK cell activity, and cytokine production were found between groups. AHCC intake resulted in the increased number of DCs and function of DC1s, which have a role in specific immunity.

Effects of Chronic Ethanol Feeding on Murine Dendritic Cell Numbers, Turnover Rate, and Dendropoiesis

Chronic alcoholics have increased susceptibility to and severity of infection, which are likely to be a result of impaired immune defense mechanisms. The contribution of dendritic cells (DC) to these immune defense changes is not well understood. Alterations in DC numbers, dendropoiesis, and lifespan have not been specifically studied in vivo in chronic ethanol (EtOH) exposure models. As DC play an essential role in initiating immune responses, alterations in these DC characteristics would help explain changes observed in adaptive immune responses. Mice received 20% EtOH (w/v) in the drinking water for up to 28 weeks, with mouse chow ad libitum. In EtOH-fed and water control mice, DC were enumerated by flow cytometry. The effect of EtOH on DC precursor numbers was determined by differentiation in vitro in the presence of granulocyte-macrophage colony-stimulating factor and interleukin-4, and the effect of an EtOH environment on untreated DC differentiation was measured following bone marrow transfer to irradiated hosts. DC turnover rate was also examined by bromodeoxyuridine incorporation and loss. The percentage and absolute numbers of DC were decreased in spleen and increased in thymus beginning as early as 4 weeks of EtOH feeding. In addition, the overall cellularity of spleen and thymus were altered by this regimen. However, chronic EtOH consumption did not adversely affect DC precursor numbers, differentiation abilities, or turnover rates. Decreased splenic DC numbers observed following chronic murine EtOH consumption are not because of altered DC precursor numbers or differentiation, nor increased DC turnover rate. Similarly, increased thymic DC numbers are not the result of alterations in DC precursor differentiation or turnover rate. Compartment size plays a role in determining splenic and thymic DC numbers following chronic EtOH feeding. EtOH-induced alterations in total DC numbers provide several mechanisms to partially explain why chronic alcoholics have increased susceptibility to infections.

Increased Survival From Stage IV Melanoma Associated With Fewer Regulatory T Cells

Melanoma often elicits a profound immune response, and this response has been exploited by various immune therapies. These immunotherapies ultimately fail, however, and advanced melanoma is uniformly fatal, suggesting the development of an immune escape mechanism. In this study, markers of immune escape including regulatory T cells (T(regs)), dendritic cells (DCs), and TGF-beta were evaluated in 14 Stage IV melanoma patients and correlated with survival. Peripheral blood mononuclear cells were isolated from Stage IV melanoma patients and analyzed for T(regs) and DCs by flow cytometry using fluorescent CD3, CD4, CD25, Lin, HLA-DR, CD11c, and CD123 antibodies. Serum TGF-beta levels were evaluated by ELISA from these patients. Clinical data were extracted from the patients' medical records. Stage IV melanoma patients with shorter survival (less than 24 mo) had a significantly higher proportion of T(regs) than those with longer survival (15% versus 8%, respectively, P = 0.004). The numbers of DCs and the serum TGF-beta levels were not significantly different in these two groups. There was an inverse relationship between the percentage of T(regs) and survival, although this did not reach statistical significance (r = -0.35, P = 0.22). There was also an inverse relationship between peripheral T(regs) and DCs. When patients were divided into groups of greater than or less than 7% T(regs), the number of total DCs was higher in the patients with fewer T(regs) than in those with more T(regs), but this did not reach statistical significance (16,535 versus 12,126 total DCs/mL, P = 0.52). In Stage IV melanoma patients, a high percentage of T(regs) appears to be associated with shorter survival. The inverse relationship of the number of DCs and T(regs) in these patients may provide an insight to the origin of this observation.

Dendritic Cells in Chronic Obstructive Pulmonary Disease

Dendritic cells (DCs) are professional antigen-presenting cells responsible for immune homeostasis. In the lung's responses to tissue damage or infection, they initiate and orchestrate innate and adaptive immunity. There are immature and mature states and at least three phenotypic and functional subsets. DCs circulate in the blood and localize to mucosal surfaces in immature form where they act as sentinels, sampling constituents of the external environment that breach the epithelium. With internalization of antigen, they are activated, mature, and migrate to draining lymph nodes to induce the proliferation and regulate the balance of Th1/Th2 T cells or to induce a state of tolerance, the last dependent on maturation status, extent of cell surface costimulatory molecule expression, and cytokine release. Cigarette smoke has modulatory effects varying with species, dose, the location examined within the lung, and the marker or technique used to identify DCs. Healthy smokers (and smokers with asthma) have reduced numbers of large airway mature DCs. In chronic obstructive pulmonary disease, the number of immature DCs is increased in small airways, whereas in smokers with chronic obstructive pulmonary disease, the total number of DCs appears to be reduced in large airways. We hypothesize that the long-term effects of cigarette smoke include reduction of DC maturation and function, changes that favor repeated infection, increased exacerbation frequency, and the altered (CD8(+) T-cell predominant) pattern of inflammation associated with this progressive chronic disease.

Chronic Ethanol Consumption Impairs Cellular Immune Responses Against HCV NS5 Protein Due to Dendritic Cell Dysfunction

Alcoholic patients with and without chronic liver disease have a high incidence of infection with hepatitis C virus (HCV). Long-term ethanol consumption in mice has been associated with a strikingly reduced CD8(+) cytotoxic T-lymphocyte (CTL) response to HCV nonstructural proteins following DNA-based immunization. This study evaluated the effect of ethanol on dendritic cells (DCs) as a mechanism(s) for reduced CTL activity. Mice were fed an ethanol-containing or isocaloric pair-fed control diet for 8 weeks, followed by DC isolation from the spleen. DCs were evaluated with respect to endocytosis properties, cell surface markers, allostimulatory activity, and cytokine production following stimulation. Immune responses to HCV NS5 protein were generated by genetic immunization. Syngeneic transfer was used to determine if DC dysfunction contributed to abnormal cellular immune responses. Long-term ethanol exposure resulted in a reduced number of splenic DCs but did not alter endocytosis capacity. There was an increase in the myeloid and a reduction in the lymphoid DC population. Ethanol reduced expression of CD40 and CD86 costimulatory molecules on resting DCs, which was corrected following stimulation with lipopolysaccharide or poly I:C. There was impaired allostimulatory activity. Cytokine profiles of DCs isolated from ethanol-fed mice were characterized by enhanced interleukin (IL)-1beta and IL-10 and decreased tumor necrosis factor alpha, IL-12, interferon gamma, and IL-6 secretion. Impaired CTL responses to NS5 were corrected by syngeneic transfer of control DCs. Altered DC function is one of the major changes induced by long-term ethanol consumption, which subsequently impairs the cellular immune response necessary for viral clearance.

Expression of the self-marker CD47 on dendritic cells governs their trafficking to secondary lymphoid organs

Dendritic cells (DCs) capture and process Ag in the periphery. Thus, traffic through lymphatic vessels is mandatory before DCs relocate to lymph nodes where they are dedicated to T-cell priming. Here, we show that the ubiquitous self-marker CD47 selectively regulates DC, but not T and B cell trafficking across lymphatic vessels and endothelial barriers in vivo. We find an altered skin DC migration and impaired T-cell priming in CD47-deficient mice at steady state and under inflammatory conditions. Competitive DC migration assays and active immunization with myeloid DCs demonstrate that CD47 expression is required on DCs but not on the endothelium for efficient DC trafficking and T-cell responses. This migratory defect correlates with the quasi-disappearance of splenic marginal zone DCs in nonmanipulated CD47-deficient mice. Nonetheless, CCR7 expression and CCL19-driven chemotaxis remain intact. Our data reveal that CD47 on DCs is a critical factor in controlling migration and efficient initiation of the immune response.

Identification of a dendritic cell population in normal testis and in chronically inflamed testis of rats with autoimmune orchitis

Experimental autoimmune orchitis (EAO) in the rat is the primary chronic animal model for the investigation of one of the main causes of male infertility, viz., testicular inflammation. Dendritic cells (DC) are potent antigen-presenting cells that play a fundamental role in autoimmune disease. We investigated the number of DC in normal testis and examined whether DC infiltrated the testis during the development of EAO. EAO was induced by active immunization with testis homogenate and adjuvants in two strains of rat (Wistar and Sprague Dawley). The presence of DC in testis was determined, 50 and 80 days after the first immunization, by immunohistochemical staining with specific antibodies (OX-62 and CD11c), and then the total number of DC was measured by stereological analysis. Labeled cells were found only in the interstitial compartment and within granulomas of EAO animals. The number of DC in EAO testes increased compared with control rats in both strains, whereas the number of OX-62+ and CD11c+ cells in adjuvant controls remained unchanged compared with untreated rats. Interspecies variations in the quantity of DC were found, with the total number of DC per testis in untreated and adjuvant control Sprague-Dawley rats being about three times higher than that seen in Wistar rats. Moreover, the increase in DC numbers at 80 days was less prominent in EAO testes of Sprague-Dawley rats than in the Wistar strain in which EAO was more severe and showed a higher number of granulomae. Thus, we have identified the DC population in normal and chronically inflamed testis. The increase in DC observed in EAO suggests that, under inflammatory conditions, the modified action(s) of these cells is a factor in the induction of the autoimmune response in testis.

Dendritic Cell Deficiency in the Blood of Kidney Transplant Patients on Long‐Term Immunosuppression: Results of a Prospective Matched‐Cohort Study

Evidence from in vitro studies suggests that immunosuppressive drugs interfere with key functions of dendritic cells (DCs), but the in vivo relevance of these findings is elusive. We prospectively analyzed the major DC precursor subsets in the blood of kidney transplant recipients on long-term immunosuppression (> or =1 year). A total of 87 patients were compared to 87 age- and sex-matched controls. Total DC numbers and the precursor subsets, myeloid type 1 DCs, myeloid type 2 DCs (mDC1, mDC2) and plasmacytoid DCs (pDCs) were identified by four color flow cytometry. Long-term immunosuppression was associated with significant reduction of all major DC subsets in comparison to healthy controls (mDC1 p < 0.001; mDC2 p < 0.0001; two-tailed Mann-Whitney U-test) with the strongest negative impact on pDCs (p < 0.00001). In contrast, total leukocyte numbers were not significantly affected. Analysis of the relative impact of different agents revealed a significant impact of prednisolone on pDCs (p = 0.009) and mDCs2 (p = 0.006). The functional relevance of pDC deficiency was confirmed independently by Interferon-alpha analysis after Toll-like receptor 7 (p < or = 0.001) and 9 (p < 0.05) stimulation. These results indicate for the first time a profound negative impact of long-term immunosuppression on major DC subsets in kidney transplant recipients. DC deficiency may have important implications with respect to viral infections and tumor development.