Since their discovery, there has been significant progress in the understanding of dendritic cell (DC) biology. Their capacity for priming an immune response against pathogens and cancers has been exploited clinically. However, the objective responses obtained to date using DC cancer vaccines have been modest. Suboptimal DC preparations, limited tumor target antigens, and the essential need to initiate trials in immunocompromised patients with advanced disease, have all contributed to limited outcomes. The use of fully activated DCs, loaded with multiple, immunoge...

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...

Antigen (Ag) capture and presentation onto major histocompatibility complex (MHC) class II molecules by B lymphocytes is mediated by their surface Ag receptor (B cell receptor [BCR]). Therefore, the transport of vesicles that carry MHC class II and BCR-Ag complexes must be coordinated for them to converge for processing. In this study, we identify the actin-associated motor protein myosin II as being essential for this process. Myosin II is activated upon BCR engagement and associates with MHC class II-invariant chain complexes. Myosin II inhibition or depletion c...

Previously, we found that human dendritic cells (hDCs) pulsed with a melanoma cell lysate (MCL) and stimulated with TNF-alpha (MCL/TNF) acquire a mature phenotype in vitro and are able to trigger tumor-specific immune responses when they are used in melanoma immunotherapy in patients. In this study, we describe that MCL/TNF induces gap junction (GJ)-mediated intercellular communications and promotes melanoma Ag transfer between ex vivo produced hDCs from melanoma patients. hDCs also exhibit increased expression of the GJ-related protein connexin 43, which contribu...

MOTIVATION: Eu.Gene Analyzer is an easy-to-use, stand-alone application that allows rapid and powerful microarray data analysis in the context of biological pathways. Its intuitive graphical user interface makes it an easy and flexible tool, even for the first-time user. Eu.Gene supports a variety of array platforms, organisms and pathway ontologies, transparently deals with multiple nomenclature systems and seamlessly integrates data from different sources. Two different statistical methods, the Fisher Exact Test and the Gene Set Enrichment Analysis (GSEA), are i...

Antigen binding to the B-cell receptor (BCR) induces multiple signaling cascades that ultimately lead to B lymphocyte activation. In addition, the BCR regulates the key trafficking events that allow the antigen to reach endocytic compartments devoted to antigen processing, i.e., that are enriched for major histocompatibility factor class II (MHC II) and accessory molecules such as H2-DM. Here, we analyze the role in antigen processing and presentation of the tyrosine kinase Syk, which is activated upon BCR engagement. We show that convergence of MHC II- and H2-DM-...

Myeloid dendritic cells (DC) and macrophages evolve from a common precursor. However, factors controlling monocyte differentiation toward DC or macrophages are poorly defined. We report that the surface density of the GM-CSF receptor (GM-CSFR) alpha subunit in human peripheral blood monocytes varies among donors. Although no correlation was found between the extent of GM-CSFR and monocyte differentiation into DC driven by GM-CSF and IL-4, GM-CSFR expression strongly influenced the generation of CD1a(+) dendritic-like cells in the absence of IL-4. CD1a(+) cells gen...

Interferon (IFN)-gamma, a cytokine critical for resistance to infection and tumors, is produced by CD4(+) helper T lymphocytes after stimulation by cultured dendritic cells (DCs) that secrete a cofactor, interleukin (IL)-12. We have identified a major IL-12-independent pathway whereby DCs induce IFN-gamma-secreting T helper (Th)1 CD4(+) T cells in vivo. This pathway requires the membrane-associated tumor necrosis family member CD70 and was identified by targeting the LACK antigen from Leishmania major within an antibody to CD205 (DEC-205), an uptake receptor on a ...

Gene MAGE-A3 encodes tumor-specific antigenic peptides recognized by T cells on many tumors. MAGE-A3 peptides presented by HLA class I molecules have been identified using CD8 lymphocytes stimulated with cells that either expressed gene MAGE-A3 or were pulsed with candidate peptides. One antigen identified with the latter method is peptide MAGE-A3(195-203) IMPKAGLLI, presented by HLA-A24 molecules. It has been used to vaccinate advanced cancer patients. Here, we have used HLA/peptide tetramers to detect T cells recognizing this peptide. Their frequency was estimat...

Cancer-germline genes (CGGs) code for immunogenic antigens that are present on various human tumors but not on normal tissues. The importance of CGGs in cancer immunotherapy has led to detailed studies of their expression in a range of human tumors. We measured the levels of expression of 12 CGGs in various pediatric solid tumors to identify targets for therapeutic cancer vaccines. Quantitative real-time PCR (qPCR) was used to measure the expression of 8 MAGE genes and of genes LAGE-2/NY-ESO-1 and GAGE-1, 2, 8 in 9 osteosarcomas, 10 neuroblastomas, 12 rhabdomyosar...

Treatment of chondrosarcomas is limited to resection because these tumors are unresponsive to standard adjuvant treatments, such as chemotherapy and radiation. We have previously shown that high-grade chondrosarcomas express unspecified members of the Melanoma Antigen (MAGE) gene family. We show here that FS human chondrosarcoma (FS) cells express MAGE-A3 gene and HLA-A1 molecules. In vitro assays show that a cytolytic T-lymphocyte clone (CTL) specific for a MAGE-A3 peptide presented by HLA-A1 specifically lysed FS chondrosarcoma cells. Addition of antigenic pepti...

The initiation of cytotoxic immune responses requires the direct interaction between naive CD8+ T lymphocytes and dendritic cells (DCs). Multiphoton imaging in intact lymph nodes (LNs) showed that during priming, naive T cells and DCs establish sequentially brief (i.e., minutes) and long (hours) antigen-specific contacts. We show here that the expression of the Intercellular Adhesion Molecule-1 (ICAM-1) by mature DCs is critical for long-lasting contacts with CD8+ T cells but dispensable for short-lived antigen-specific interactions. Serial brief DC-T cell contact...

Naive T lymphocytes move efficiently in lymphoid tissues while scanning dendritic cells in search of cognate complexes of peptide in major histocompatibility molecules. However, T cell migration ceases after recognition of cognate antigen. We show here that during the initiation of antigen-specific CD8(+) T cell responses, naive CD8(+) polyclonal T cells 'preferentially' interacted in an antigen-independent way with mature dendritic cells competent to present antigen to antigen-specific CD8(+) T cells. These antigen-independent interactions required expression of ...

To prevent excessive degradation of internalized antigens, which could destroy the peptides recognized by T lymphocytes, dendritic cells have developed several strategies that limit proteolytic activity in phagosomes. The recruitment of the NADPH oxidase NOX2 prevents acidification of phagosomes, limiting antigen degradation. Here, we show that dendritic cells derived from Rab27a-deficient ashen mice show increased phagosome acidification and antigen degradation, causing a defect in antigen cross-presentation. Enhanced acidification results from a delay in the rec...

To initiate adaptative cytotoxic immune responses, proteolytic peptides derived from phagocytosed antigens are presented by dendritic cells (DCs) to CD8+ T lymphocytes through a process called antigen "crosspresentation." The partial degradation of antigens mediated by lysosomal proteases in an acidic environment must be tightly controlled to prevent destruction of potential peptides for T cell recognition. We now describe a specialization of the phagocytic pathway of DCs that allows a fine control of antigen processing. The NADPH oxidase NOX2 is recruited to the ...

Exosomes are secreted vesicles formed in late endocytic compartments. Mature dendritic cells (DCs) secrete exosomes bearing functional MHC-peptide complexes and high levels of ICAM-1. Such exosomes can activate Ag-specific naive T cells but only after recapture by recipient APCs. In this study, we addressed the molecular mechanisms of interaction between exosomes and recipient DCs. We show that exosomes can be presented by mouse DCs without the need for internalization and processing. Exosomes interact with DCs through a specific saturable receptor. Although the t...

Mature dendritic cells (DCs) are the most potent antigen-presenting cells within the human immune system. However, Herpes simplex virus type 1 (HSV-1) is able to interfere with DC biology and to establish latency in infected individuals. In this study, we provide new insights into the mechanism by which HSV-1 disarms DCs by the manipulation of CD83, a functionally important molecule for DC activation. Fluorescence-activated cell sorter (FACS) analyses revealed a rapid downmodulation of CD83 surface expression within 6 to 8 h after HSV-1 infection, in a manner stri...