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There are adaptive T-cell and antibody autoimmune responses to myelin-derived peptides in multiple sclerosis (MS) and to aquaporin-4 (AQP4) in neuromyelitis optica spectrum disorders (NMOSDs). Strategies aimed at antigen-specific tolerance to these autoantigens are thus indicated for these diseases. One approach involves induction of tolerance with engineered dendritic cells (tolDCs) loaded with specific antigens. We conducted an in-human phase 1b clinical trial testing increasing concentrations of autologous tolDCs loaded with peptides from various myelin proteins and from AQP4. We tested this approach in 12 patients, 8 with MS and 4 with NMOSD. The primary end point was the safety and tolerability, while secondary end points were clinical outcomes (relapses and disability), imaging (MRI and optical coherence tomography), and immunological responses. Therapy with tolDCs was well tolerated, without serious adverse events and with no therapy-related reactions. Patients remained stable clinically in terms of relapse, disability, and in various measurements using imaging. We observed a significant increase in the production of IL-10 levels in PBMCs stimulated with the peptides as well as an increase in the frequency of a regulatory T cell, known as Tr1, by week 12 of follow-up. In this phase 1b trial, we concluded that the i.v. administration of peptide-loaded dendritic cells is safe and feasible. Elicitation of specific IL-10 production by peptide-specific T cells in MS and NMOSD patients indicates that a key element in antigen specific tolerance is activated with this approach. The results warrant further clinical testing in larger trials., Competing Interests: Conflict of interest statement: E.F. and L.S. published an obituary on two leaders in MS [Kildebeck EJ, et al. (2017) The emergence of neuroepidemiology, neurovirology and neuroimmunology: The legacies of John F. Kurtzke and Richard “Dick” T. Johnson. J Neurol 264:817–828]. I.Z. has received travel reimbursement from Genzyme, Biogen, and Merck for national and international meetings over the last 3 y. E.H.M.-L. has received speaker honoraria from Biogen, Roche, Novartis, and Sanofi and a travel reimbursement from Biogen, Roche, Novartis, and Sanofi. E.H.M.-L. has participated in advisory boards for Roche and Sanofi. A.S. has received compensation for consulting services and speaker honoraria from Bayer-Schering, Merck-Serono, Biogen-Idec, Sanofi-Aventis, Teva Pharmaceutical Industries Ltd., Roche, and Novartis. S.L. has received speaker honoraria and travel reimbursement from Biogen, Merck, Novartis, and Teva. I.P.-V. has received travel reimbursement from Roche Spain and Genzyme-Sanofi, European Academy of Neurology, and the European Committee for Treatment and Research in Multiple Sclerosis for international and national meetings over the last 3 y; I.P.-V. holds a patent for an affordable eye-tracking system to measure eye movement in neurologic diseases and holds stock in Aura Innovative Robotics. N.S.-V. received compensation for consulting services and speaker honoraria from Genzyme-Sanofi, Biogen idec, Merck-Serono, and Bayer-Schering. P.V. holds stocks and has received compensation from Bionure Farma SL; Health Engineering SL; Spiral Therapeutics, Inc.; and QMenta SL. L.S. received compensation from Novartis, Celgene, Bionure, Tolerion, Katexco, Atreca, and TG Therapeutics. All other authors declare no conflict of interest., (Copyright © 2019 the Author(s). Published by PNAS.)

The identification of activated T-lymphocytes restricted to myelin-derived immunogenic peptides in multiple sclerosis (MS) and aquaporin-4 water channel in neuromyelitis optica (NMO) in the blood of patients opened the possibility for developing highly selective and disease-specific therapeutic approaches. Antigen presenting cells and in particular dendritic cells (DCs) represent a strategy to inhibit pro-inflammatory T helper cells. DCs are located in peripheral and lymphoid tissues and are essential for homeostasis of T cell-dependent immune responses. The expression of a particular set of receptors involved in pathogen recognition confers to DCs the property to initiate immune responses. However, in the absence of danger signals different DC subsets have been revealed to induce active tolerance by inducing regulatory T cells, inhibiting pro-inflammatory T helper cells responses or both. Interestingly, several protocols to generate clinical-grade tolerogenic DC (Tol-DC) in vitro have been described, offering the possibility to restore the homeostasis to central nervous system-related antigens. In this review, we discuss about different DC subsets and their role in tolerance induction, the different protocols to generate Tol-DCs and preclinical studies in animal models as well as describe recent characterization of Tol-DCs for clinical application in autoimmune diseases and in particular in MS and NMO patients. In addition, we discuss the clinical trials ongoing based on Tol-DCs to treat different autoimmune diseases.

Background: Autologous tumour lysate dendritic cell vaccine (ADC) has T-cell stimulatory capacity and, therefore, potential antitumour activity. We designed a phase II randomised trial of ADC + best supportive care (BSC) (experimental arm [EA]) compared with BSC (control arm [CA]), in pre-treated metastatic colorectal cancer (mCRC) patients., Patients and Methods: Patients with progressive mCRC, at least to two chemotherapy regimens and Eastern Cooperative Oncology Group performance status (ECOG PS) 0-2, were randomised to EA versus CA. Stratification criteria: ECOG PS (0-1 versus 2) and lactate dehydrogenase (ULN). EA was administered subcutaneously till progressive disease. Primary end-point was progression-free survival (PFS) at 4 months., Results: Fifty-two patients were included (28 EA/24 CA). An interim analysis recommended early termination for futility. No objective radiological response was observed in EA. Median PFS in EA was 2.7 months (95% confidence interval [CI], 2.3-3.2 months) versus 2.3 months (95% CI, 2.1-2.5 months) in CA (p = 0.628). Median overall survival (OS) was 6.2 months (95% CI, 4.4-7.9 months) in EA versus 4.7 months (95% CI, 2.3-7 months) in CA (p = 0.41). No ADC-related adverse events were reported. Immunization induces tumour-specific T-cell response in 21 of 25 (84%) patients. Responder patients have an OS of 7.3 months (95% CI, 5.2-9.4 months) versus 3.8 months (95% CI, 0.6-6.9 months) in non-responders; p = 0.026)., Conclusion: Our randomised clinical trial comparing ADC + BSC versus BSC in mCRC demonstrates that ADC generates a tumour-specific immune response but not benefit on PFS and OS. Our results do not support the use of ADC alone, in a phase III trial., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Cellular therapies using immune cells and in particular dendritic cells (DCs) are being increasingly applied in clinical trials and vaccines. Their success partially depends on accurate delivery of cells to target organs or migration to lymph nodes. Delivery and subsequent migration of cells to regional lymph nodes is essential for effective stimulation of the immune system. Thus, the design of an optimal DC therapy would be improved by optimizing technologies for monitoring DC trafficking. Magnetic resonance imaging (MRI) represents a powerful tool for non-invasive imaging of DC migration in vivo. Domestic pigs share similarities with humans and represent an excellent animal model for immunological studies. The aim of this study was to investigate the possibility using pigs as models for DC tracking in vivo. Porcine monocyte derived DC (MoDC) culture with superparamagnetic iron oxide (SPIO) particles was standardized on the basis of SPIO concentration and culture viability. Phenotype, cytokine production and mixed lymphocyte reaction assay confirmed that porcine SPIO-MoDC culture were similar to mock MoDCs and fully functional in vivo. Alike, similar patterns were obtained in human MoDCs. After subcutaneous inoculation in pigs, porcine SPIO-MoDC migration to regional lymph nodes was detected by MRI and confirmed by Perls staining of draining lymph nodes. Moreover, after one dose of virus-like particles-pulsed MoDCs specific local and systemic responses were confirmed using ELISPOT IFN-γ in pigs. In summary, the results in this work showed that after one single subcutaneous dose of pulsed MoDCs, pigs were able to elicit specific local and systemic immune responses. Additionally, the dynamic imaging of MRI-based DC tracking was shown using SPIO particles. This proof-of-principle study shows the potential of using pigs as a suitable animal model to test DC trafficking with the aim of improving cellular therapies., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Vaccination against cancer by using dendritic cells has for more than a decade been based on dendritic cells generated ex vivo from monocytes or CD34(+) progenitors. Here, we report on the first clinical study of therapeutic vaccination against cancer using naturally occurring plasmacytoid dendritic cells (pDC). Fifteen patients with metastatic melanoma received intranodal injections of pDCs activated and loaded with tumor antigen-associated peptides ex vivo. In vivo imaging showed that administered pDCs migrated and distributed over multiple lymph nodes. Several patients mounted antivaccine CD4(+) and CD8(+) T-cell responses. Despite the limited number of administered pDCs, an IFN signature was observed after each vaccination. These results indicate that vaccination with naturally occurring pDC is feasible with minimal toxicity and that in patients with metastatic melanoma, it induces favorable immune responses.

Dendritic cells have been investigated in clinical trials, predominantly with the aim of stimulating immune responses against tumours or infectious diseases. Thus far, however, no clinical studies have taken advantage of their specific immunosuppressive potential. Tolerogenic DCs may represent a new therapeutic strategy for human immune-based diseases, such as Crohn's disease, where the perturbations of the finely tuned balance between the immune system and the microflora result in disease. In the present report, we describe the generation of tolerogenic DCs from healthy donors and Crohn's disease patients using clinical-grade reagents in combination with dexamethasone as immunosuppressive agent and characterize their response to maturation stimuli. Interestingly, we found out that dexamethasone-conditioned DCs keep their tolerogenic properties to Gram-negative bacteria. Other findings included in this study demonstrate that the combination of dexamethasone with a specific cytokine cocktail yielded clinical-grade DCs with the following characteristics: a semi-mature phenotype, a pronounced shift towards anti-inflammatory versus inflammatory cytokine production and low T-cell stimulatory properties. Importantly, in regard to their clinical application, the tolerogenic phenotype of DCs remained stable after the elimination of dexamethasone and after a second stimulation with LPS or bacteria. All these properties make this cell product suitable to be tested in clinical trials of inflammatory conditions including Crohn's disease.

DEC-205 is a type I C-type lectin receptor (CLR) that is expressed on various APC subsets and has been suggested to bind necrotic and apoptotic cells. Here we study DEC-205 characteristics in plasmacytoid DCs (pDCs) obtained from healthy individuals and assess its ability to mediate antigen presentation by isolating sufficient numbers of pDCs from apheresis material obtained from stage III/IV melanoma patients. The results demonstrate that DEC-205 is expressed on human pDCs. Internalization of DEC-205 after antibody ligation is clathrin- and dynamin-dependent as it is blocked by hypertonic shock or by inhibition of dynamin activity. Antibody targeting to DEC-205 does not affect TLR-induced expression levels of co-stimulatory and MHC molecules, but clearly impairs TLR-induced IFN-α secretion by 40%. We observed that TLR-mediated signaling increases DEC-205 expression levels without affecting receptor internalization. Moreover, human pDCs retained the capacity to present antigens via DEC-205 following TLR activation., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Dendritic cells are a heterogeneous population of bone marrow derived leucocytes that play a crucial role in both pathogen recognition and the initiation of primary T cell immune responses. Plasmacytoid dendritic cells (pDCs), also known as natural interferon-producing cells, comprise one of two major human dendritic cell subsets that strongly influences immune balance. pDCs remain a poorly characterized subset. Several studies have suggested the existence of a close phenotypic and functional relationship between B-cells and pDCs. The surface reactivity of a panel of 96 monoclonal antibodies submitted to the ninth Human Leukocyte Differentiation Antigens workshop (HLDA9) B cell section was analyzed using pDCs as target cells. The results showed that eight of the mAbs reacted positively on pDCs: CD86, CD229, CD319, CD305, CD184, CD84, CD85g and FcɛRIa, confirming previously published reports. Interestingly, this study also revealed the expression of eight surface molecules not previously described on pDCs, including CD352(NTBA), CD272(BTLA), CD357(GITR), CD48, CD270(HVEM), Galectin-3, CD148, and CD361. The present report summarizes the expression of these molecules on freshly isolated pDCs. Significantly, we have identified several new molecules expressed by these intriguing cells, ones we believe will open new avenues for the study of pDC functionality and their role in human health and diseases., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Dendritic cells (DCs) are central players of the immune response. To date, DC-based immunotherapy is explored worldwide in clinical vaccination trials with cancer patients, predominantly with ex vivo-cultured monocyte-derived DCs (moDCs). However, the extensive culture period and compounds required to differentiate them into DCs may negatively affect their immunological potential. Therefore, it is attractive to consider alternative DC sources, such as blood DCs. Two major types of naturally occurring DCs circulate in peripheral blood, myeloid DCs (mDCs) and plasmacytoid (pDCs). These DC subsets express different surface molecules and are suggested to have distinct functions. Besides scavenging pathogens and presenting antigens, DCs secrete cytokines, all of which is vital for both the acquired and the innate immune system. These immunological functions relate to Toll-like receptors (TLRs) expressed by DCs. TLRs recognize pathogen-derived products and subsequently provoke DC maturation, antigen presentation and cytokine secretion. However, not every TLR is expressed on each DC subset nor causes the same effects when activated. Considering the large amount of clinical trials using DC-based immunotherapy for cancer patients and the decisive role of TLRs in DC maturation, this review summarizes TLR expression in different DC subsets in relation to their function. Emphasis will be given to the therapeutic potential of TLR-matured DC subsets for DC-based immunotherapy.

Currently dendritic cell (DC)-based vaccines are explored in clinical trials, predominantly in cancer patients. Murine studies showed that only maturation with Toll-like receptor (TLR) ligands generates mature DCs that produce interleukin-12 and promote optimal T-cell help. Unfortunately, the limited availability of clinical-grade TLR ligands significantly hampers the translation of these findings into DC-based vaccines. Therefore, we explored 15 commonly used preventive vaccines as a possible source of TLR ligands. We have identified a cocktail of the vaccines BCG-SSI, Influvac, and Typhim that contains TLR ligands and is capable of optimally maturing DCs. These DCs (vaccine DCs) showed high expression of CD80, CD86, and CD83 and secreted interleukin-12. Although vaccine DCs exhibited an impaired migratory capacity, this could be restored by addition of prostaglandin E(2) (PGE(2); vaccine PGE(2) DCs). Vaccine PGE(2) DCs are potent inducers of T-cell proliferation and induce Th1 polarization. In addition, vaccine PGE(2) DCs are potent inducers of tumor antigen-specific CD8(+) effector T cells. Finally, vaccine PGE(2)-induced DC maturation is compatible with different antigen-loading strategies, including RNA electroporation. These data thus identify a new clinical application for a mixture of commonly used preventive vaccines in the generation of Th1-inducing clinical-grade mature DCs.

Tumor-derived peptides are used frequently as antigen (Ag) source in dendritic cell (DC) therapy in cancer patients. An alternative is to load DC with tumor-associated Ag (TAA)-encoding RNA. RNA-loading obviates prior knowledge of CTL and Th epitopes in the Ag. Multiple epitopes for many HLA alleles (both MHC class I and class II) are encoded by the RNA and loading is independent of the patient's HLA make-up. Herein, we determined the optimal conditions for mRNA-electroporation of monocyte-derived DC for clinical application in relation to different maturation cocktails. The data demonstrate that TAA carcinoembryonic antigen, gp100 and tyrosinase are expressed already 30 min after electroporation with the encoding mRNA. Moreover, gp100-specific CTL are activated by gp100 mRNA-electroporated DC. Importantly, we show here that the presence of polyinosinic-polycytidylic acid [poly(I:C)] in the maturation cocktail prevents effective protein expression of the electroporated mRNA as well as subsequent CTL recognition. This effect of poly(I:C) correlates with the induction of IFN-induced genes and innate anti-viral effector molecules in DC. Together these data show that electroporation of mature DC with TAA-encoding mRNA is attractive for use in DC vaccination protocols in cancer patients, but protein expression should be tested for each maturation cocktail.

Dendritic cells (DC) are professional antigen-presenting cells of the immune system that play a key role in regulating T cell-based immunity. In vivo, the capacity of DC to activate T cells depends on their ability to migrate to the T cell areas of lymph nodes as well as on their maturation state. Depending on their cytokine-secreting profile, DC are able to skew the immune response in a specific direction. In particular, IL-12p70 producing DC drive T cells towards a T helper 1 type response. A serious disadvantage of current clinical grade ex vivo generated monocyte-derived DC is the poor IL-12p70 production. We have investigated the effects of Toll-like receptor (TLR)-mediated maturation on ex vivo generated human monocyte-derived DC. We demonstrate that in contrast to cytokine-matured DC, DC matured with poly(I:C) (TLR3 ligand) and/or R848 (TLR7/8 ligand) are able to produce vast amounts of IL-12p70, but exhibit a reduced migratory capacity. The addition of prostaglandin E2 (PGE2) improved the migratory capacity of TLR-ligand matured DC while maintaining their IL-12p70 production upon T cell encounter. We propose a novel clinical grade maturation protocol in which TLR ligands poly(I:C) and R848 are combined with PGE2 to generate DC with both high migratory capacity and IL-12p70 production upon T cell encounter.

Human plasmacytoid dendritic cells (pDCs)(2) exploit Ag uptake receptors like CD32a for internalization of exogenous Ags. Activation of pDC by TLR9 ligand CpG-C induces strong maturation. Surprisingly, we observed that CpG-C-stimulated pDCs showed impaired Ag-specific T cell proliferation whereas the induction of allogeneic T cell proliferation was not affected. We demonstrated that signals from TLR9 caused a rapid down-regulation of the capacity of pDC to take-up Ab-Ag complexes without altering their CD32a expression, thus explaining the reduced Ag presentation. The recent contrasting biological responses that were observed upon TLR9 ligation in pDCs prompted us to study the effect of several TLR9 ligands. We observed that type I IFN-inducer CpG-A, localizing in the early endosomal compartment, did not affect CD32a function, whereas CpGs localizing in the late endosomes and inducing pDC maturation clearly inhibited CD32a-mediated Ag uptake and presentation. We conclude that TLR9 ligands not only determine the type of response, i.e., type I IFN production (innate immunity) or maturation (adaptive immunity), but also directly affect Ag presentation capacity of pDCs. We hypothesize that pDC, once activated via TLR9-ligands reaching the late endosomes, can only present initially sampled Ags and thus are protected from uptake and processing of additional potential self-Ags.

C-type lectin receptors (CLRs) fulfill multiple functions within the immune system by recognition of carbohydrate moieties on foreign or (altered) self-structures. CLRs on myeloid dendritic cells (DCs) have been well characterized as pattern-recognition receptors (PRRs) combining ligand internalization with complex signaling events. Much less is known about CLR expression and function in human plasmacytoid DCs (pDCs), the major type I interferon (IFN) producers. In this study, we demonstrate that, next to the CLR BDCA-2, human pDCs express DC immunoreceptor (DCIR), a CLR with putative immune-inhibitory function, but not dectin-1, mannose receptor, or DC-specific ICAM-3-grabbing nonintegrin. DCIR surface levels are reduced on pDC maturation after TLR9 triggering. Interestingly, DCIR triggering inhibits TLR9-induced IFN-alpha production while leaving up-regulation of costimulatory molecule expression unaffected. Furthermore, DCIR is readily internalized into pDCs after receptor triggering. We show that DCIR internalization is clathrin-dependent because it can be inhibited by hypertonic shock and dominant-negative dynamin. Importantly, antigens targeted to pDCs via DCIR are presented to T cells. These findings indicate that targeting DCIR on pDCs not only results in efficient antigen presentation but also affects TLR9-induced IFN-alpha production. Collectively, the data show that targeting of DCIR can modulate human pDC function and may be applied in disease prevention and treatment.

Plasmacytoid dendritic cells (pDCs) contribute to innate antiviral immune responses by producing type I interferons. Although human pDCs can induce T cell responses upon viral infection, it remains unclear if pDCs can present exogenous antigens. Here, we show that human pDCs exploit FcgammaRII (CD32) to internalize antigen-antibody complexes, resulting in the presentation of exogenous antigen to T cells. pDCs isolated from melanoma patients vaccinated with autologous monocyte-derived peptide- and keyhold limpet hemocyanin (KLH)-loaded dendritic cells, but not from nonvaccinated patients or patients that lack a humoral response against KLH, were able to stimulate KLH-specific T cell proliferation. Interestingly, we observed that internalization of KLH by pDCs depended on the presence of serum from vaccinated patients that developed an anti-KLH antibody response. Anti-CD32 antibodies inhibited antigen uptake and presentation, demonstrating that circulating anti-KLH antibodies binding to CD32 mediate KLH internalization. We conclude that CD32 is an antigen uptake receptor on pDCs and that antigen presentation by pDCs is of particular relevance when circulating antibodies are present. Antigen presentation by pDCs may thus modulate the strength and quality of the secondary phase of an immune response.

Background and objective: Diffuse intrinsic pontine glioma (DIPG) is a lethal brainstem tumor in children. Dendritic cells (DCs) have T-cell stimulatory capacity and, therefore, potential antitumor activity for disease control. DCs vaccines have been shown to reactivate tumor-specific T cells in both clinical and preclinical settings. We designed a phase Ib immunotherapy (IT) clinical trial with the use of autologous dendritic cells (ADCs) pulsed with an allogeneic tumors cell-lines lysate in patients with newly diagnosed DIPG after irradiation (radiation therapy). Methods: Nine patients with newly diagnosed DIPG met enrollment criteria. Autologous dendritic cell vaccines (ADCV) were prepared from monocytes obtained by leukapheresis. Five ADCV doses were administered intradermally during induction phase. In the absence of tumor progression, patients received three boosts of tumor lysate every 3 months during the maintenance phase. results: Vaccine fabrication was feasible in all patients included in the study. Nonspecific KLH (9/9 patients) and specific (8/9 patients) antitumor response was identified by immunologic studies in peripheral blood mononuclear cells (PBMC). Immunological responses were also confirmed in the T lymphocytes isolated from the cerebrospinal fluid (CSF) of two patients. Vaccine administration resulted safe in all patients treated with this schema. Conclusion: These preliminary results demonstrate that ADCV preparation is feasible, safe, and generate a DIPG-specific immune response detected in PBMC and CSF. This strategy shows a promising backbone for future schemas of combination IT. [ABSTRACT FROM AUTHOR]

Dendritic cells (DC) are professional antigen-presenting cells of the immune system that play a key role in regulating T cell-based immunity. In vivo, the capacity of DC to activate T cells depends on their ability to migrate to the T cell areas of lymph nodes as well as on their maturation state. Depending on their cytokine-secreting profile, DC are able to skew the immune response in a specific direction. In particular, IL-12p70 producing DC drive T cells towards a T helper 1 type response. A serious disadvantage of current clinical grade ex vivo generated monocyte-derived DC is the poor IL-12p70 production. We have investigated the effects of Toll-like receptor (TLR)-mediated maturation on ex vivo generated human monocyte-derived DC. We demonstrate that in contrast to cytokine-matured DC, DC matured with poly(I:C) (TLR3 ligand) and/or R848 (TLR7/8 ligand) are able to produce vast amounts of IL-12p70, but exhibit a reduced migratory capacity. The addition of prostaglandin E2 (PGE2) improved the migratory capacity of TLR-ligand matured DC while maintaining their IL-12p70 production upon T cell encounter. We propose a novel clinical grade maturation protocol in which TLR ligands poly(I:C) and R848 are combined with PGE2 to generate DC with both high migratory capacity and IL-12p70 production upon T cell encounter. [ABSTRACT FROM AUTHOR]

Plasmacytoid dendritic cells (pDCs) contribute to innate antiviral immune responses by producing type I interferons. Although human pDCs can induce T cell responses upon viral infection, it remains unclear if pDCs can present exogenous antigens. Here, we show that human pDCs exploit Fcγ/RII (CD32) to internalize antigen-antibody complexes, resulting in the presentation of exogenous antigen to T cells, pDCs isolated from melanoma patients vaccinated with autologous monocyte-derived peptide- and keyhold limpet hemocyanin (KLH)-loaded dendritic cells, but not from nonvaccinated patients or patients that lack a humoral response against KLH, were able to stimulate KLH-specific T cell proliferation. Interestingly, we observed that internalization of KLH by pDCs depended on the presence of serum from vaccinated patients that developed an anti-KLH antibody response. Anti-CD32 antibodies inhibited antigen uptake and presentation, demonstrating that circulating anti-KLH antibodies binding to CD32 mediate KLH internalization. We conclude that CD32 is an antigen uptake receptor on pDCs and that antigen presentation by pDCs is of particular relevance when circulating antibodies are present. Antigen presentation by pDCs may thus modulate the strength and quality of the secondary phase of an immune response. [ABSTRACT FROM AUTHOR]

Cancer vaccines are a type of immune therapy that seeks to modulate the host's immune system to induce durable and protective immune responses against cancer-related antigens. The little clinical success of therapeutic cancer vaccines is generally attributed to the immunosuppressive tumor microenvironment at late-stage diseases. The administration of cancer-preventive vaccination at early stages, such as pre-malignant lesions or even in healthy individuals at high cancer risk could increase clinical efficacy by potentiating immune surveillance and pre-existing specific immune responses, thus eliminating de novo appearing lesions or maintaining equilibrium. Indeed, research focus has begun to shift to these approaches and some of them are yielding encouraging outcomes. [ABSTRACT FROM AUTHOR]

Abstract: Synthetic oligonucleotide ligands that bind to toll-like receptors are known to modulate the immune response via the activation of antigen presenting cells, and were therefore proposed as a novel form of vaccine adjuvant. Clinical-grade they are, however, not readily available. Here, we show that commonly used prophylactic vaccines for infectious diseases like measles, mumps and tuberculosis exhibit the same immune modulating behavior as synthetic CpG oligonucleotides in terms of their ability to stimulate IFN-α production and plasmacytoid dendritic cell maturation. Featuring the additional advantages of low-cost and proven safety, these vaccines could therefore be attractive alternatives to CpG oligonucleotides as adjuvants for immunotherapy. This previously undiscovered characteristic of prophylactic vaccines also sheds new light on the mechanisms by which they operate and is extremely interesting for vaccine development. Moreover, the finding that prophylactic vaccines trigger TLRs like synthetic oligonucleotides opens the possibility to predict the immune response of new vaccines. [Copyright &y& Elsevier]