Early in life, thymic export establishes the size and the diversity of the human naive T-cell pool. Yet, on puberty thymic activity drastically decreases. Because the overall size of the naive T-cell pool decreases only marginally during ageing, peripheral postthymic expansion of naive T cells has been postulated to account partly for the maintenance of T-cell immunity in adults. So far, the analysis of these processes had been hampered by the inability to distinguish recent thymic emigrants from proliferated, peripheral, naive T cells. However, recently, CD31 ha...

Cancer results from a tumor cell intrinsic dysregulation of oncogenes, tumor suppressor and stability genes as well as from the avoidance of immunosurveillance. A complex network of cellular interactions allows one to mount cognate anti-tumor immune responses. Recently, discoveries have been made regarding the links between innate and cognate antitumor immunity eliciting protective T-cell responses. The intricate differentiation pathway, whereby dendritic cells can efficiently mature in the tumor microenvironment, appears crucial for the priming of T cells. Transf...

In contrast to prior belief, tumor cell apoptosis is not necessarily silent but can be immunogenic. By tracing how anthracyclines and gamma-irradiation trigger immunogenic cell deaths, we found that they were causally connected to the exposure of calreticulin on the tumor cell surface, before apoptosis in the tumor cell itself occurred. Furthermore, we showed that calreticulin exposure was necessary and sufficient to increase proimmunogenic killing by other chemotherapies. Our findings suggest that calreticulin could serve as a biomarker to predict therapy-associa...

BACKGROUND: Dendritic cells (DC) are the professional antigen-presenting cells of the immune system, fully equipped to prime naive T cells and thus essential components for cancer immunotherapy. METHODS: We tested the influence of several elements (cPPT, trip, WPRE, SIN) on the transduction efficiency of human DC. Human and murine DC were transduced with tNGFR-encoding lentiviruses to assess the effect of transduction on phenotype and function. Human DC were transduced with lentiviruses encoding huIi80MAGE-A3 and murine DC with huIi80tOVA to test antigen presenta...

Lentiviral vectors have emerged as promising tools for both gene therapy and immunotherapy purposes. They exhibit several advantages over other viral systems in that they are less immunogenic and are capable of transducing a wide range of different cell types, including dendritic cells (DC). DC transduced ex vivo with a whole range of different (tumor) antigens were capable of inducing strong antigen-specific T-cell responses, both in vitro and in vivo. Recently, the administration of lentiviral vectors in vivo has gained substantial interest as an alternative me...

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...

Tumors can regress as a result of invading myeloid and lymphoid cells that act in concert. Although the myeloid cells are widely recognized as antigen presenters and lymphoid cells as classical effectors, recent evidence revealed the capacity of dendritic cells (DC) to kill tumor cells. The functional concept of 'natural killer (NK) myeloid DC' is supported by mouse and human in vitro data that may be clinically relevant because human killer DC can contribute to tumor shrinking during topical therapy with toll-like receptor (TLR) agonists. Whether tumor killing b...

Tumor immunosurveillance is mediated by innate and adaptive components of cellular immunity. A complex network of cellular interactions is needed to elicit protective antitumoral CD4+and CD8+T cell responses. Thereby dendritic cells (DCs) play a central role as professional antigen presenting cells (APCs) that take up antigens, process, and present them to prime naïve T cells. Recognition and lysis of tumor cells has been attributed to innate effectors such as natural killer (NK), NKT and gammadeltaT cells. Recently, novel subsets of cytotoxic DCs, called "kille...

It is generally accepted that active therapeutic immunization approaches hold great promise for treating malignant tumors. In recent years, lentiviral vectors have emerged as promising tools for anti-tumor immunotherapy due to their capacity to transduce a wide range of different dividing and non-dividing cell types, including tumor cells and dendritic cells (DC). The latter are considered to be the key regulators of immunity and are therefore applied as 'nature's adjuvant' in terms of eliciting strong antigen-specific cytotoxic T lymphocyte responses against tum...

Mass spectrometry (MS)-based proteomics has become a formidable tool for the investigation of posttranslational modifications to proteins, protein interactions, and organelles. Is it now ready to tackle comprehensive protein expression analysis?

T lymphocytes lacking the lymph node-homing receptors L-selectin and CCR7 do not migrate to lymph nodes in the steady state. Instead, we found here that lymph nodes draining sites of mature dendritic cells or adjuvant inoculation recruited L-selectin-negative CCR7- effector and memory CD8+ T cells. This recruitment required CXCR3 expression on T cells and occurred through high endothelial venules in concert with lumenal expression of the CXCR3 ligand CXCL9. In reactive lymph nodes, recruited T cells established stable interactions with and killed antigen-bearing d...

Dectin-1 is a pattern-recognition receptor recognizing beta-(1,3)-glucans found on fungal cell walls. Dectin-1 plays an important role in immunity to fungi by mediating phagocytic clearance of fungal particles and inducing transcription of innate response genes. We show here that the two processes are linked and that Dectin-1 signalling for inflammation is attenuated by phagocytosis. Blocking Dectin-1 ligand-dependent internalization using either actin polymerization or dynamin inhibitors, large non-phagocytosable beta-glucan particles or poorly phagocytic cells ...

IL-10 is a potent anti-inflammatory cytokine interfering with antigen presentation by inducing the intracellular sequestration of MHC class II (MHC-II) molecules. Here we studied the contribution of membrane-associated RING-CH (MARCH) ubiquitin ligase family members to the IL-10-induced down-regulation of MHC-II molecules. We found that MARCH1 and MARCH8 proteins are the most potent family members for the down-regulation of MHC-II surface expression in transfected cells, but only MARCH1 mRNA expression is strongly induced by IL-10 in human primary monocytes. We d...

Infection with influenza A virus (IAV) presents a substantial threat to public health worldwide, with young, elderly, and immunodeficient individuals being particularly susceptible. Inflammatory responses play an important role in the fatal outcome of IAV infection, but the mechanism remains unclear. We demonstrate here that the absence of invariant NKT (iNKT) cells in mice during IAV infection resulted in the expansion of myeloid-derived suppressor cells (MDSCs), which suppressed IAV-specific immune responses through the expression of both arginase and NOS, resu...

The surface phenotype CD3-NK1.1+DX5+CD11c(int)B220+GR1- has been recently ascribed to a novel subset of mouse leukocytes termed interferon (IFN)-producing killer dendritic cells (IKDCs) that shares functions with natural killer (NK) cells and DCs. Interleukin-15 (IL-15) is critical for NK cells but its relationship with IKDC remained unexplored. An expression cassette encoding human IL-15 (hIL-15) has been transferred by hydrodynamic injection into the liver of mice, resulting in transient expression of the cytokine that is detectable during the first 48 h. hIL-1...

BACKGROUND: Inefficient migration of dendritic cells (DC) to regional lymph nodes (LN) upon intracutaneous injection is a major obstacle for effective DC vaccination. Intravenous vaccination is unfavorable, because DC cannot migrate directly from the blood into LN. METHODS: To enable human monocyte-derived (mo)DC to enter LN directly from the blood, we manipulated them by RNA electroporation to express a human chimeric E/L-selectin (CD62E/CD62L) protein, which binds to peripheral node addressin expressed on high endothelial venules. RESULTS: Transfection efficienc...