Dendritic cell (DC) derived-exosomes (Dex) are nanomeric vesicles harboring functional MHC/peptide complexes promoting T cell-dependent tumor rejection. In the first Phase I trial using peptide-pulsed Dex, the observation of clinical regressions in the absence of T cell responses prompted the search for alternate effector mechanisms. Mouse studies unraveled the bioactivity of Dex on NK cells. Indeed, Dex promoted an IL-15Ralpha- and NKG2D-dependent NK cell proliferation and activation respectively, resulting in anti-metastatic effects mediated by NK1.1(+) cells. ...

Tumor growth results from a delicate balance between intrinsic dysregulation of oncogenes, tumor suppressor and stability genes counteracted by extrinsic defenses composed of immune cells shaping tumor immunogenicity. Although immune subversion might be the ultimate outcome of this process, a complex network of cellular interactions take place eventually leading to tumor specific cognate immune responses. The links between innate and cognate antitumor immunity eliciting protective T cell responses are instigated by cytokines, chemokines and damage associated mole...

The quality of signals received by dendritic cells (DC) in response to pathogens influences the nature of the adaptive response. We show that pathogen-derived signals to DC mediated via TLRs can be modulated by activated invariant NKT (iNKT) cells. DC maturation induced in vivo with any one of a variety of TLR ligands was greatly improved through simultaneous administration of the iNKT cell ligand -galactosylceramide. DC isolated from animals treated simultaneously with TLR and iNKT cell ligands were potent stimulators of naive T cells in vitro compared with DC fro...

We have addressed the hypothesis that Notch ligands play a decisive role in determining the ability of antigen-presenting cells to influence T cell polarization. Dendritic cells displayed distinct expression profiles of Delta and Jagged ligands for Notch when exposed to biologically relevant pathogen preparations associated with Th1 or Th2 responses. Expression of delta4 was increased, and jagged2 decreased, after dendritic cell exposure to the Th1-promoting bacterium Propionibacterium acnes. In contrast, soluble egg antigen (SEA) from the parasitic helminth Schi...

Antigen-loaded dendritic cells (DCs) have been intensively investigated as potential cellular antitumor vaccines. Several recent reports have indicated that loading DCs with whole tumor derived mRNA or defined tumor-antigen-encoding mRNA represents an effective nonviral strategy to stimulate T cell responses both for in vitro and in vivo models. Here, we describe the electroporation method as a tool for introducing in vitro transcribed capped mRNA into human DCs for tumor vaccination. We use MART-1/Melan-A as a model tumor-associated antigen for the generation of...

BACKGROUND: The advent of Systems Biology has been accompanied by the blooming of pathway databases. Currently pathways are defined generically with respect to the organ or cell type where a reaction takes place. The cell type specificity of the reactions is the foundation of immunological research, and capturing this specificity is of paramount importance when using pathway-based analyses to decipher complex immunological datasets. Here, we present DC-ATLAS, a novel and versatile resource for the interpretation of high-throughput data generated perturbing the si...

Invariant NKT cells (iNKT cells) recognize CD1d/glycolipid complexes. We demonstrate that the nonglycosidic compound threitolceramide efficiently activates iNKT cells, resulting in dendritic cell (DC) maturation and the priming of Ag-specific T and B cells. Threitolceramide-pulsed DCs are more resistant to iNKT cell-dependent lysis than alpha-galactosylceramide-pulsed DCs due to the weaker affinity of the human iNKT TCR for CD1d/ threitolceramide than CD1d/alpha-galactosylceramide complexes. iNKT cells stimulated with threitolceramide also recover more quickly fr...

The discovery of tumor-associated antigens, which are either selectively or preferentially expressed by tumors, together with an improved insight in dendritic cell biology illustrating their key function in the immune system, have provided a rationale to initiate dendritic cell-based cancer immunotherapy trials. Nevertheless, dendritic cell vaccination is in an early stage, as methods for preparing tumor antigen presenting dendritic cells and improving their immunostimulatory function are continuously being optimized. In addition, recent improvements in immunomon...

Th cells producing IL-17 play a pro-inflammatory role at mucosal surfaces. Treg at the same sites dampen inflammation and prevent immunopathology. Th cells producing IL-17 (Th17) and Treg are thought to be distinct populations defined by expression of the transcription factors ROR-gammat and Foxp3, respectively. Here, we show that mouse CD25(+)Foxp3(+) Treg can be converted into a hybrid T-cell population characterized by the expression of Foxp3 and ROR-gammat and the production of IL-17. Conversion was observed upon coculture with DC selectively activated via de...

Mass spectrometry is a powerful technology for the analysis of large numbers of endogenous proteins. However, the analytical challenges associated with comprehensive identification and relative quantification of cellular proteomes have so far appeared to be insurmountable. Here, using advances in computational proteomics, instrument performance and sample preparation strategies, we compare protein levels of essentially all endogenous proteins in haploid yeast cells to their diploid counterparts. Our analysis spans more than four orders of magnitude in protein abu...

From cancerous and non-cancerous patients, we derived stable clones of CD4(+) Treg, defined as clones that expressed high CD25 at rest, were anergic in vitro, and suppressed the proliferation of co-cultured CD4(+) cells. A conserved region of FOXP3 intron 1 was demethylated in all Treg clones, whereas it was methylated in non-regulatory Th and CTL clones. In our panel of human clones, this stable epigenetic mark correlated better with suppressive activity than did FOXP3 mRNA or protein expression. We used expression microarrays to compare Treg and Th clones after...

Dendritic cells (DCs) are crucial in immune induction. Not only do they collect antigens in peripheral tissues, and transport and process them for presentation to lymphocytes in draining lymph nodes, but they also regulate the immune response by modulating T-cell differentiation. Intestinal and hepatic DCs migrating in lymph can be collected from rats under near-physiological conditions. Initially, the mesenteric or celiac lymph nodes are removed from young rats (30 min). The afferent and efferent lymph vessels subsequently heal, permitting DCs to enter the thorac...

Although dendritic cells (DCs) play an important role in mediating protection against influenza virus, the precise role of lung DC subsets, such as CD11b- and CD11b+ conventional DCs or plasmacytoid DCs (pDCs), in different lung compartments is currently unknown. Early after intranasal infection, tracheal CD11b-CD11chi DCs migrated to the mediastinal lymph nodes (MLNs), acquiring co-stimulatory molecules in the process. This emigration from the lung was followed by an accumulation of CD11b+CD11chi DCs in the trachea and lung interstitium. In the MLNs, the CD11b+ ...

Immunization with purified antigens is a safe and practical vaccination strategy but is generally unable to induce sustained CD8(+) T cell-mediated protection against intracellular pathogens. Most efforts to improve the CD8(+) T cell immunogenicity of these vaccines have focused on co-administration of adjuvant to support cross-presentation and dendritic cell maturation. In addition, it has been shown that CD4(+) T cell help during the priming phase contributes to the generation of protective CD8(+) memory T cells. In this report we demonstrate that the depletion...

Covalent conjugation of synthetic Toll-like receptor ligands (TLR-L) to synthetic antigenic peptides provides well-defined constructs that have significantly improved capacity to induce efficient priming of CD8(+) T lymphocytes in vivo. We have recently explored the cellular mechanisms underlying the efficient induction of a CD8(+) cytotoxic T lymphocyte response by such synthetic model vaccines [Khan, S., Bijker, M.S., Weterings, J.J., Tanke, H.J., Adema, G.J., van, H.T., Drijfhout, J.W., Melief, C.J., Overkleeft, H.S., van der Marel, G.A., Filippov, D.V., van d...

Dendritic cells (DCs) play a critical role in orchestrating the innate and adaptive components of the immune system so that appropriate, coordinated responses are mounted against infectious agents. Tissue-resident DCs interact with microbes through germline-encoded pattern-recognition receptors (PRRs), which recognize molecular patterns expressed by various microorganisms. Antigens use PRR activation to instruct DCs for the appropriate priming of natural killer (NK) cells, followed by specific T-cell responses. Due to the central role of DCs in regulating the act...

Therapeutic vaccination trials, in which patients with cancer were vaccinated with minimal CTL peptide in oil-in-water formulations, have met with limited success. Many of these studies were based on the promising data of mice studies, showing that vaccination with a short synthetic peptide in IFA results in protective CD8(+) T cell immunity. By use of the highly immunogenic OVA CTL peptide in IFA as a model peptide-based vaccine, we investigated why minimal CTL peptide vaccines in IFA performed so inadequately to allow full optimization of peptide vaccination. In...