Search

Patients with inborn errors of the alternative NF-κB pathway have low thymic AIRE expression, leading to the development of auto-Abs neutralizing type I IFNs, and severe viral diseases.

Pneumocystis jirovecii is recognized as an opportunistic pathogen in immunosuppressed patients. We report a case of severe Pneumocystis pneumonia (PCP) in an infant with acquired combined immunodeficiency secondary to maternal chemotherapy exposure during the second and third trimesters of pregnancy. The infant required cardiorespiratory support with veno-venous extracorporeal membrane oxygenation (VV-ECMO) for severe respiratory failure. This case highlights the potential for severe acquired immunodeficiency in this patient cohort and further postnatal surveillance is highly recommended.

Pneumocystis jirovecii is recognized as an opportunistic pathogen in immunosuppressed patients. We report a case of severe Pneumocystis pneumonia (PCP) in an infant with acquired combined immunodeficiency secondary to maternal chemotherapy exposure during the second and third trimesters of pregnancy. The infant required cardiorespiratory support with veno-venous extracorporeal membrane oxygenation (VV-ECMO) for severe respiratory failure. This case highlights the potential for severe acquired immunodeficiency in this patient cohort and further postnatal surveillance is highly recommended.

Anti-N-Methyl-D-Aspartate-receptor encephalitis is the most common antibody-mediated autoimmune encephalopathy. A HIV-infected African boy presented with subacute psychosis as manifestation of anti-N-Methyl-D-Aspartate-receptor encephalitis. Intravenous immunoglobulin and corticosteroids induced complete remission. Although this is the first pediatric case described, 5 adult cases have been reported. The role of HIV in the etiology of this autoimmune condition requires further exploration.

Acute Plasmodium infections in humans result in dendritic cell dysfunction and apoptosis caused in part by elevated levels of IL-10., Malaria causes significant morbidity worldwide and a vaccine is urgently required. Plasmodium infection causes considerable immune dysregulation, and elicitation of vaccine immunity remains challenging. Given the central role of dendritic cells (DCs) in initiating immunity, understanding their biology during malaria will improve vaccination outcomes. Circulating DCs are particularly important, as they shape immune responses in vivo and reflect the functional status of other subpopulations. We performed cross-sectional and longitudinal assessments of the frequency, phenotype, and function of circulating DC in 67 Papuan adults during acute uncomplicated P. falciparum, P. vivax, and convalescent P. falciparum infections. We demonstrate that malaria patients display a significant reduction in circulating DC numbers and the concurrent accumulation of immature cells. Such alteration is associated with marked levels of spontaneous apoptosis and impairment in the ability of DC to mature, capture, and present antigens to T cells. Interestingly, sustained levels of plasma IL-10 were observed in patients with acute infection and were implicated in the induction of DC apoptosis. DC apoptosis was reversed upon IL-10 blockade, and DC function recovered when IL-10 levels returned to baseline by convalescence. Our data provide key information on the mechanisms behind DC suppression during malaria and will assist in developing strategies to better harness DC’s immunotherapeutic potential.

Development of a vaccine that targets blood-stage malaria parasites is imperative if we are to sustainably reduce the morbidity and mortality caused by this infection. Such a vaccine should elicit long-lasting immune responses against conserved determinants in the parasite population. Most blood-stage vaccines, however, induce protective antibodies against surface antigens, which tend to be polymorphic. Cell-mediated responses, on the other hand, offer the theoretical advantage of targeting internal antigens that are more likely to be conserved. Nonetheless, few of the current blood-stage vaccine candidates are able to harness vigorous T cell immunity. Here, we present what we believe to be a novel blood-stage whole-organism vaccine that, by combining low doses of killed parasite with CpG-oligodeoxynucleotide (CpG-ODN) adjuvant, was able to elicit strong and cross-reactive T cell responses in mice. Our data demonstrate that immunization of mice with 1,000 killed parasites in CpG-ODN engendered durable and cross-strain protection by inducing a vigorous response that was dependent on CD4+ T cells, IFN-gamma, and nitric oxide. If applicable to humans, this approach should facilitate the generation of robust, cross-reactive T cell responses against malaria as well as antigen availability for vaccine manufacture.

The generation of antitumour immunity depends on the nature of dendritic cell (DC)-tumour interactions. These have been studied mostly by using in vitro-derived DC which may not reflect the natural biology of DC in vivo. In breast cancer, only one report has compared blood DC at different stages and no longitudinal evaluation has been performed. Here we conducted three cross-sectional and one one-year longitudinal assessments of blood DC in patients with early (stage I/II, n=137) and advanced (stage IV, n=36) disease compared to healthy controls (n=66). Patients with advanced disease exhibit markedly reduced blood DC counts at diagnosis. Patients with early disease show minimally reduced counts at diagnosis but a prolonged period (1 year) of marked DC suppression after tumour resection. While differing in frequency, DC from both patients with early and advanced disease exhibit reduced expression of CD86 and HLA-DR and decreased immunostimulatory capacities. Finally, by comparing a range of clinically available maturation stimuli, we demonstrate that conditioning with soluble CD40L induces the highest level of maturation and improved T-cell priming. We conclude that although circulating DC are compromised by loco-regional and systemic breast cancer, they respond vigorously to ex vivo conditioning, thus enhancing their immunostimulatory capacity and potential for immunotherapy.

There are 300-500 million cases of malaria each year and of the more than one million people that die each year from malaria, most are children under 5 years of age. The cloning of malaria antigens in 1983 offered great hope of developing a viable subunit vaccine. While some subunit vaccines have shown great promise in model systems, an efficacious human vaccine is still not available. Immunological studies have shown that numerous factors such as parasite's antigenic variation and polymorphism, immunological non-responsiveness to individual vaccine antigens, parasite-induced apoptosis of immune effector and memory cells, immune deviation as a result of maternal immunity and alterations of dendritic cell function can impede the development of vaccines. These findings indicate that alternative novel approaches are required to tackle the disease and induce protection against malaria.

Malaria is a major global health problem and vaccine development is an imperative. However, the complexity of the malaria parasite has made vaccine development incredibly difficult. Recent data indicate that strategies that combine many antigens to induce maximal responses to protective determinants are likely to be more successful than those based on single antigens. Whole parasite approaches have also shown success in animal and human studies.

Dendritic cells (DC) have been implicated in the defective function of the immune system during cancer progression. We have demonstrated that patients with cancer have fewer myeloid (CD11c+) and plasmacytoid (CD123(hi)) DC and a concurrent accumulation of CD11c(-)CD123- immature cells expressing HLA-DR (DR(+)IC). Notably, DR(+)IC from cancer patients have a reduced capacity to stimulate allogeneic T-cells. DR(+)IC are also present in healthy donors, albeit in smaller numbers. In this study, we assessed whether DR(+)IC could have an impact on the immune response by comparing their function with DC counterparts. For this purpose, DR(+)IC and DC were purified and tested in the presentation of antigens through major histocompatibility complex (MHC) II and MHC-I molecules. DR(+)IC were less efficient than DC at presenting antigens to T-cells. DR(+)IC induced a limited activation of T-cells, eliciting poor T-helper (Th) 1 and preferentially inducing Th2-biased responses. Importantly, despite DR(+)IC's poor responsiveness to inflammatory factors, in samples from healthy volunteers and breast cancer patients, CD40 ligation induced phenotypic maturation and interleukin 12 secretion, in turn generating more efficient T-cell responses. These data underscore the importance of inefficient antigen presentation as a mechanism for tumor evasion and suggest an approach to improve the efficacy of DC-based immunotherapy for cancer.

Dendritic cell (DC) defects are an important component of immunosuppression in cancer. Here, we assessed whether cancer could affect circulating DC populations and its correlation with tumor progression. The blood DC compartment was evaluated in 136 patients with breast cancer, prostate cancer, and malignant glioma. Phenotypic, quantitative, and functional analyses were performed at various stages of disease. Patients had significantly fewer circulating myeloid (CD11c+) and plasmacytoid (CD123+) DC, and a concurrent accumulation of CD11c(-)CD123(-) immature cells that expressed high levels of HLA-DR+ immature cells (DR(+)IC). Although DR(+)IC exhibited a limited expression of markers ascribed to mature hematopoietic lineages, expression of HLA-DR, CD40, and CD86 suggested a role as antigen-presenting cells. Nevertheless, DR(+)IC had reduced capacity to capture antigens and elicited poor proliferation and interferon-gamma secretion by T-lymphocytes. Importantly, increased numbers of DR(+)IC correlated with disease status. Patients with metastatic breast cancer showed a larger number of DR(+)IC in the circulation than patients with local/nodal disease. Similarly, in patients with fully resected glioma, the proportion of DR(+)IC in the blood increased when evaluation indicated tumor recurrence. Reduction of blood DC correlating with accumulation of a population of immature cells with poor immunologic function may be associated with increased immunodeficiency observed in cancer.

Several reports have demonstrated that tumours are not intrinsically resistant to the immune response. However, neoplasias commonly fail to initiate and maintain adequate immunity. A number of factors have been implicated in causing the failure, including aberrant antigen processing by tumour cells, anergy or deletion of T cells, and recruitment of inhibitory/regulatory cell types. It has been suggested that dysfunction of dendritic cells (DC) induced by the tumour is one of the critical mechanisms to escape immune surveillance. As a minor subset of leucocytes, DC are the key APC for initiating immune responses. DC are poised at the boundaries of the periphery and the inner tissues, sampling antigens of diverse origin. Following their encounter with antigen or danger signals, DC migrate to lymph nodes, where they activate effector cells essential for tumour clearance. Although the DC system is highly heterogeneous, the differentiation and function of DC populations is largely regulated by exogenous factors. Malignancies appear to exploit this by producing a plethora of immunosuppressive factors capable of affecting DC, thus exerting systemic effects on immune function. This review examines recent findings on the effects of tumour-derived factors inducing DC dysfunction and in particular examines the findings on alteration of DC differentiation, maturation and longevity as a potent mechanism for immune suppression in cancer.

Dendritic cells (DC) from distinct DC subsets are essential contributors to normal human immune responses. Despite this, reliable assays that enable DC to be counted precisely have been slow to evolve. We have now developed a new single-platform flow cytometric assay based on TruCOUN(TM) beads and the whole blood Lyse/No-Wash protocol that allows precise counting of the CD14(-) blood DC subsets: CD11c(+)CD16(-) DC, CD11c(+)CD16(+) DC, CD123(hi) DC, CD1c(+) DC and BDCA-3(+) DC. This assay requires 50 mul of whole blood; does not rely on a hematology blood analyser for the absolute DC counts; allows DC counting in EDTA samples 24 It after collection; and is suitable for cord blood and peripheral blood. The data is highly reproducible with intra-assay and inter-assay coefficients of variation less than 3% and 11%, respectively. This assay does not produce the DC-T lymphocyte conjugates that result in DC counting abnormalities in conventional gradient-density separation procedures. Using the TruCOUNT assay, we established that absolute blood DC counts reduce with age in healthy individuals. In preliminary studies, we found a significantly lower absolute blood CD11c(+)CD16(+) DC count in stage III/IV versus stage I/II breast carcinoma patients and a lower absolute blood CD123(hi) DC count in multiple myeloma patients, compared to age-matched controls. These data indicate that scientific progress in DC counting technology will lead to the global standardization of DC counting and allow clinically meaningful data to be obtained. (C) 2003 Elsevier B.V. All rights reserved.

Cerebral malaria is a severe complication of malaria. Sequestration of parasitized RBCs in brain microvasculature is associated with disease pathogenesis, but our understanding of this process is incomplete. In this study, we examined parasite tissue sequestration in an experimental model of cerebral malaria (ECM). We show that a rapid increase in parasite biomass is strongly associated with the induction of ECM, mediated by IFN-γ and lymphotoxin α, whereas TNF and IL-10 limit this process. Crucially, we discovered that host CD4+ and CD8+ T cells promote parasite accumulation in vital organs, including the brain. Modulation of CD4+ T cell responses by helminth coinfection amplified CD4+ T cell-mediated parasite sequestration, whereas vaccination could generate CD4+ T cells that reduced parasite biomass and prevented ECM. These findings provide novel insights into immune-mediated mechanisms of ECM pathogenesis and highlight the potential of T cells to both prevent and promote infectious diseases.

Perpetuation of immune deficiency throughout tumor development is, to a great degree, the result of impairment of dendritic cell function by products secreted by tumors. They include cytokines, non-tumor-specific molecules (gangliosides, prostanoids, nitric oxide, etc.) and tumor-(specific) antigens (MUC-1, PSA, Her-2 neu). They may engender a distortion of dendritic cell development, block dendritic cell maturation, induce dendritic cell apoptosis or interfere with antigen presentation. Identifying those molecules and their interaction with dendritic cells will accelerate the development of more efficient immunotherapies. In this chapter we review the current literature on these interactions and highlight the possible avenues of minimization of their deleterious effects.

Malaria is a significant health problem causing morbidity and mortality worldwide. Vaccine development has been an imperative for decades. However, the intricacy of the parasite's lifecycle coupled with the lack of evidence for robust infection-induced immunity has made vaccine development exceptionally difficult.To review some of the key advances in the field and discuss potential ways forward for a whole-organism vaccine.The authors searched PubMed using the words 'malaria and vaccine'. We searched for manuscripts detailing antigen characterisation and vaccine strategies with emphasis on subunit versus whole-parasite approaches. Abstracts were selected and relevant articles are discussed. The searches were not restricted by language or date.The early cloning of malaria antigens has fuelled rapid development of subunit vaccines. However, the disappointing results of clinical trials have resulted in reappraisal of current strategies. Whole-parasite approaches have re-emerged as an alternative strategy. Immunization using radiation or genetically attenuated sporozoites has been shown to result in sterile immunity and immunization with blood-stage parasites curtailed by antimalarials has demonstrated delayed parasitemia in rodent models as well as in human malaria.

Malaria is an infectious disease that causes serious morbidity and mortality worldwide. The disease is associated with a variety of clinical syndromes ranging from asymptomatic to lethal infections involving anaemia, organ failure, pulmonary and cerebral disease. The molecular and cellular factors responsible for the differences in disease severity are poorly understood but parasite-specific immune responses are thought to play a critical role in pathogenesis. Dendritic cells have an essential role in linking innate and adaptive immune responses and here we review their role in the context of malaria.

Novel adjuvant therapies are urgently needed to complement the existing treatment options for breast cancer. The advent of the use of dendritic cells (DCs) for cancer immunotherapy provides a unique opportunity to overcome the relative non-immunogenic property of breast tumours and address the underlying immunodeficiency. To date, the success of this approach has been limited, possibly due to the targeting of specific tumour antigens that rapidly mutate and, thus, become undetectable to the immune system. A more efficient approach would include preparations encompassing multiple antigens, such as those provided by loading of whole tumour cells or tumour RNA. It is proposed that targeting mammary stem cells responsible for resistance to chemo/immunotherapy, through the expression of a broad array of wild-type and mutated tumour antigens in the context of DCs, will become a mainstay for immunotherapy of breast cancer.

Dendritic cells (DC) for cancer immunotherapy protocols are generated most commonly by in vitro differentiation of monocytes with exogenous cytokines (Mo-DC). However, Mo-DC differ in their molecular phenotype and function from blood DC (BDC). Clinical isolation of BDC has been limited to the use of density gradients, which result in low yields of variable purity. We have developed a DC enrichment platform, which uses the CMRF-44 (IgM) or CMRF-56 (IgG) monoclonal antibodies (mAb) to select BDC that express these antigens after a short overnight incubation. After culture of peripheral blood mononuclear cells (PBMC) in autologous/AB serum, biotinylated CMRF-44 was used to select DC in a single step immuno-magnetic bead procedure; this produced populations containing up to 99% CMRF-44(+) cells, including up to 67% CMRF-44(+) CD14(-) CD19(-) DC, from an initial starting population of approximately 0.5%. We observed consistent differences in the purities obtained from individual donors with a mean of 54% CMRF-44(+) cells (range 19-99%). Similar results were obtained using biotinylated CMRF-56 mAb, an antibody identifying a comparable population in cultured PBMC. We recovered an average of 54% and 66% of the available BDC in separations performed with the CMRF-44 and CMRF-56 mAb, respectively. The reproducibility of the procedure and the ability to perform it in a closed sterile system makes it suitable for clinical use. Larger scale preparations starting from apheresis derived PBMC will produce sufficient BDC for immunotherapy protocols. The purified BDC elicited strong allogeneic mixed leukocyte reactions and HLA classes II- and I-restricted antigen-specific primary immune responses.