Biomedical subjects

Stefan Endres

Publications and source records attributed to Stefan Endres.

At least 37 records · Page 2Linked to original sources

PubMed2003

Intratumoral immunization with tumor RNA-pulsed dendritic cells confers antitumor immunity in a C57BL/6 pancreatic murine tumor model.

Pancreatic tumors lack adequate recruitment of immunocompetent cells, especially dendritic cells (DCs). We have shown previously that coculturing of natural killer-like T cells with DCs transfected with pancreatic tumor cell line-derived RNA reverses pancreatic carcinoma cell resistance by directly triggering natural killer-like T lymphocytes in vitro. In the present study, we tested triggering of specific T lymphocytes in vivo by using an immunocompetent mouse strain (C57BL/6). Syngenic, bone marrow-derived DCs were pulsed with tumor RNA derived from the pancreatic cell line PANC02. This cell line is a ductal pancreatic adenocarcinoma and shows high resistance to every known class of clinically active antitumor agent. PANC02 cells were implanted orthotopically via ultrasound guidance and led to pancreatic tumor formation in all of the mice. Thereafter, tumor RNA-pulsed DCs were injected intratumorally. Intratumoral administration of tumor RNA-pulsed DCs induced significantly more potent protective immunity than s.c. or i.v. administration. It was significantly more effective than administration with unpulsed DCs or DCs pulsed with a control tumor RNA derived from a lymphomatous cell line (EL4). The antitumor effect was caused by induction of antigen-specific T lymphocytes as shown by additional in vitro studies. These results favor intratumoral injection of tumor RNA-pulsed DCs for immunotherapy of pancreatic cancer.

Animals↗

PubMed2003

CpG-A and CpG-B oligonucleotides differentially enhance human peptide-specific primary and memory CD8+ T-cell responses in vitro.

Two distinct types of CpG oligodeoxynucleotide (ODN) have been identified that differ in their capacity to stimulate antigen-presenting cells: CpG-A induces high amounts of interferon-alpha (IFN-alpha) and IFN-beta in plasmacytoid dendritic cells (PDCs), whereas CpG-B induces PDC maturation and is a potent activator of B cells but stimulates only small amounts of IFN-alpha and IFN-beta. Here we examined the ability of these CpG ODNs to enhance peptide-specific CD8+ T-cell responses in human peripheral blood mononuclear cells (PBMCs). The frequency of influenza matrix-specific "memory" CD8+ T cells was increased by both types of CpG ODN, whereas the frequency of Melan-A specific "naive" CD8+ T cells increased on stimulation with CpG-B but not with CpG-A. The presence of PDCs in PBMCs was required for this CpG ODN-mediated effect. The expanded cells were cytotoxic and produced IFN- on peptide restimulation. Soluble factors induced by CpG-A but not CpG-B increased the granzyme-B content and cytotoxicity of established CD8+ T-cell clones, each of which was IFN-alpha/-beta dependent. In conclusion, CpG-B seems to be superior for priming CD8+ T-cell responses, and CpG-A selectively enhances memory CD8+ T-cell responses and induces cytotoxicity. These results demonstrate distinct functional properties of CpG-A and CpG-B with regard to CD8 T cells.

Antigens, Neoplasm↗

PubMed2003

The interleukin-1 beta-converting enzyme inhibitor pralnacasan reduces dextran sulfate sodium-induced murine colitis and T helper 1 T-cell activation.

The proinflammatory cytokines interleukin (IL)-1beta and IL-18 are supposed to play a crucial role in the pathogenesis of human inflammatory bowel disease. To exert biological activity, the precursors of both IL-1beta and IL-18 need to be cleaved by the interleukin-1beta-converting enzyme (ICE). IL-18 induces the synthesis of IFN-gamma in T cells and NK cells. In the present study, we investigated the effect of the specific ICE inhibitor pralnacasan in dextran sulfate sodium-induced murine colitis. Colitis was induced in BALB/c mice by 3.5% dextran sulfate sodium dissolved in drinking water for 10 days. Pralnacasan was administered either intraperitoneally or orally every day. To assess in vivo efficacy, a clinical disease activity score was evaluated daily. Colon length, expression of IL-18 in colonic tissue, expression of interferon-gamma (IFN-gamma) in paraaortal lymphocytes, and systemic production of IFN-gamma in splenocytes were analyzed post mortem. Intraperitoneally administered pralnacasan significantly reduced the clinical score compared with the dextran sulfate sodium control group from day 6 to day 10. Oral administration of pralnacasan also significantly reduced the clinical score at days 8 and 9. Administration of pralnacasan i.p. reduced the expression of intracolonic IL-18 significantly. Furthermore, pralnacasan reduced the number of IFN-gamma-positive lymphocytes in paraaortal lymph nodes. IFN-gamma synthesis in stimulated splenocytes was significantly suppressed in all pralnacasan-treated groups. No side effects of pralnacasan were observed. In conclusion, pralnacasan is effective in the prevention of dextran sulfate sodium-induced colitis. This effect is probably mediated by suppression of the proinflammatory cytokines IL-18, IL-1beta, and IFN-gamma.

Animals↗

PubMed2003

Development of a new protocol for 2-day generation of mature dendritic cells from human monocytes.

We developed a new 2-day protocol for the generation of dendritic cells (DCs) from human monocytes in vitro. First, we demonstrated that 24 hours of culture with GM-CSF and IL-4 are sufficient to generate immature DCs capable of antigen uptake. We then compared two different strategies for DC maturation: proinflammatory mediators were either added together with GM-CSF and IL-4 from the beginning of cell culture or added after 24 hours of differentiation with GM-CSF and IL-4. After 48 hours of total culture period, expression of activation markers was more pronounced in cells generated by the 2-step differentiation and activation method. Our new protocol for 2-day DC differentiation reduces labor, cost and time and also reliably renders high numbers of mature and viable DCs.

Journal Article↗

PubMed2003

Identification and functional analysis of tumor-infiltrating plasmacytoid dendritic cells in head and neck cancer.

The antitumor activity of IFN-alpha is well established. However, the role of the plasmacytoid dendritic cell (PDC), the major producer of IFN-alpha upon viral infection, in tumor biology is unknown. We sought to study the presence and function of PDC in a human solid tumor. Here, we demonstrate that PDCs infiltrate tumor tissue of patients with head and neck squamous cell carcinoma (HNSCC). Functional activity of PDC was examined by using CpG motif containing oligonucleotides, a defined microbial stimulus for PDCs (recognized via toll-like receptor 9). We found that HNSCC diminished the ability of PDC to produce IFN-alpha in response to CpG motif containing oligonucleotide. Tumor-induced down-regulation of toll-like receptor 9 was identified as one mechanism likely contributing to impaired PDC function within the tumor environment. In tumor-draining lymph nodes, suppression of CpG-induced IFN-alpha production was less pronounced than in single-cell suspensions of primary tumor tissue. In these lymph nodes, CpG-induced IFN-alpha production was associated with increased levels of interferon-induced protein 10 and IFN-gamma and activation of CD4 and CD8 T cells. These results show for the first time the presence of PDCs in human solid tumor tissue and that tumors suppress the capacity of PDCs to produce IFN-alpha. PDCs, which in the absence of appropriate stimulation are reported to promote regulatory CD8 T cells, may contribute to an impaired T-cell-mediated immune response in HNSCC.

Adolescent↗

PubMed2003

Activation with CpG-A and CpG-B oligonucleotides reveals two distinct regulatory pathways of type I IFN synthesis in human plasmacytoid dendritic cells.

Two different CpG oligonucleotides (ODN) were used to study the regulation of type I IFN in human plasmacytoid dendritic cells (PDC): ODN 2216, a CpG-A ODN, known to induce high amounts of IFN-alpha in PDC, and ODN 2006, a CpG-B ODN, which is potent at stimulating B cells. CpG-A ODN showed higher and prolonged kinetics of type I IFN production compared with that of CpG-B ODN. In contrast, CpG-B ODN was more active than CpG-A ODN in stimulating IL-8 production and increasing costimulatory and Ag-presenting molecules, suggesting that CpG-A and CpG-B trigger distinct regulatory pathways in PDC. Indeed, CpG-A ODN, but not CpG-B ODN, activated the type I IFNR-mediated autocrine feedback loop. PDC were found to express high constitutive levels of IFN regulatory factor (IRF)7. IRF7 and STAT1, but not IRF3, were equally up-regulated by both CpG-A and CpG-B. CD40 ligand synergistically increased CpG-B-induced IFN-alpha independent of the IFNR but did not affect CpG-B-induced IFN-beta. In conclusion, our studies provide evidence for the existence of two distinct regulatory pathways of type I IFN synthesis in human PDC, one dependent on and one independent of the IFNR-mediated feedback loop. The alternate use of these pathways is based on the type of stimulus rather than the quantity of IFN-alphabeta available to trigger the IFNR. Constitutive expression of IRF7 and the ability to produce considerable amounts of IFN-alpha independent of the IFNR seem to represent characteristic features of PDC.

Adjuvants, Immunologic↗

PubMed2003

Mature dendritic cells derived from human monocytes within 48 hours: a novel strategy for dendritic cell differentiation from blood precursors.

It is widely believed that generation of mature dendritic cells (DCs) with full T cell stimulatory capacity from human monocytes in vitro requires 5-7 days of differentiation with GM-CSF and IL-4, followed by 2-3 days of activation. Here, we report a new strategy for differentiation and maturation of monocyte-derived DCs within only 48 h of in vitro culture. Monocytes acquire immature DC characteristics by day 2 of culture with GM-CSF and IL-4; they down-regulate CD14, increase dextran uptake, and respond to the inflammatory chemokine macrophage inflammatory protein-1alpha. To accelerate DC development and maturation, monocytes were incubated for 24 h with GM-CSF and IL-4, followed by activation with proinflammatory mediators for another 24 h (FastDC). FastDC expressed mature DC surface markers as well as chemokine receptor 7 and secreted IL-12 (p70) upon CD40 ligation in the presence of IFN-gamma. The increase in intracellular calcium in response to 6Ckine showed that chemokine receptor 7 expression was functional. When FastDC were compared with mature monocyte-derived DCs generated by a standard 7-day protocol, they were equally potent in inducing Ag-specific T cell proliferation and IFN-gamma production as well as in priming autologous naive T cells using tetanus toxoid as a model Ag. These findings indicate that FastDC are as effective as monocyte-derived DCs in stimulating primary, Ag-specific, Th 1-type immune responses. Generation of FastDC not only reduces labor, cost, and time required for in vitro DC development, but may also represent a model more closely resembling DC differentiation from monocytes in vivo.

CD40 Ligand↗

PubMed2003

CpG-A oligonucleotides induce a monocyte-derived dendritic cell-like phenotype that preferentially activates CD8 T cells.

Human B cells and plasmacytoid dendritic cells recognize CpG motifs within microbial DNA via Toll-like receptor 9. Two functionally distinct types of CpG motif containing oligonucleotides (CpG ODN) have been described, CpG-A and CpG-B. In contrast to CpG-B, CpG-A induces high amounts of type I IFN (IFN-alpha and IFN-beta) in plasmacytoid dendritic cells. In the present study, we examined the effects of CpG-A on human primary monocytes. In PBMC stimulated with CpG-A and GM-CSF, monocytes showed excellent survival, increased in size and granularity, and within 3 days developed a dendritic cell-like phenotype that was characterized by down-regulation of CD14, partial up-regulation of CCR7, and an increased surface expression of costimulatory and Ag-presenting molecules. This effect could be inhibited by a combination of blocking Abs to type I IFN, and no such CpG-A-induced changes were observed in purified monocytes. Although IL-12 production by this dendritic cell-like phenotype required additional stimulation with CD40 ligand, this cell type spontaneously up-regulated IL-15 expression. Consistent with the known effect of IL-15 on effector and memory CD8 T cells, the frequency of CCR7(-)/CD45RA(-) CD8 T cells was selectively increased in allogeneic T cell assays. Furthermore, this dendritic cell type was more potent to support both the generation and the IFN-gamma production of autologous influenza matrix peptide-specific memory CD8 T cells as compared with dendritic cells generated in the presence of GM-CSF and IL-4. In conclusion, monocytes exposed to the cytokine milieu provided by CpG-A rapidly develop a dendritic cell-like phenotype that is well equipped to support CD8 T cell responses.

Adjuvants, Immunologic↗

PubMed2003

The specific type-4 phosphodiesterase inhibitor mesopram alleviates experimental colitis in mice.

Mesopram, a specific inhibitor of type-4 phosphodiesterase, decreases the synthesis of tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma). In the present study, we investigated the effect of mesopram in dextran sulfate sodium (DSS)-induced murine colitis. In the preventive model, colitis was induced by DSS simultaneously with the application of mesopram in BALB/c mice. In the therapeutic model, colitis was induced in BALB/c mice by DSS over 7 days. At day 8, DSS was discontinued, and treatment was started. Mesopram was applied intraperitoneally or orally. The clinical score was calculated daily during the course of each study. Post mortem, colon length, histologic score, and expression of TNF-alpha and IFN-gamma in colons were determined. In the preventive model, mesopram significantly reduced the maximal clinical score, decreased colon shortening, and the histologic score. A dose finding study, using the preventive model, showed that most clinical and post mortem benefit was achieved with 50 mg/kg mesopram compared with 2 and 10 mg/kg. In the therapeutic model, i.p. mesopram treatment led to a significant reduction of clinical score. Both, i.p. and p.o. mesopram significantly reversed DSS-induced colon shortening and reduced the ex vivo colonic production of IFN-gamma. We conclude that the specific type-4 phosphodiesterase inhibitor mesopram ameliorates murine colitis both in a preventive and a therapeutic setting.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed2003

Rational design of new CpG oligonucleotides that combine B cell activation with high IFN-alpha induction in plasmacytoid dendritic cells.

Two different types of CpG motif-containing oligonucleotides (CpG ODN) have been described: CpG-A with high induction of IFN-alpha in plasmacytoid dendritic cells; and CpG-B with little induction of IFN-alpha, but potent activation of B cells. In this study, we demonstrate that CpG-A fail to activate B cells unless plasmacytoid dendritic cells are present. We identified a new set of CpG ODN sequences which induces high levels of IFN-alpha in plasmacytoid dendritic cells but remains capable of directly activating B cells. These new CpG ODN (termed CpG-C) are more potent stimulants of B cells than CpG-B due to their ability of directly and indirectly (via plasmacytoid dendritic cells) activating B cells. The sequence of CpG-C combines structural elements of both CpG-A and CpG-B. The most potent sequence, M362, contains a 5'-end 'TCGTCG-motif' and a 'GTCGTT-motif', both of which are present in CpG-B (ODN 2006); a palindromic sequence characteristic for CpG-A (ODN 2216); but no poly G motif required for CpG-A. In conclusion, we defined the first CpG-containing sequences that potently activate both TLR9-expressing immune cell subsets in humans, the plasmacytoid dendritic cell and the B cell. CpG-C may allow for improved therapeutic immuno-modulation in vivo.

Adjuvants, Immunologic↗

PubMed2003

Design and implementation of a common drug information database for a university hospital.

BACKGROUND: Providing high quality problem-oriented drug information relies on the ability to easily collect appropriate background information on clinical cases, to access relevant information from published sources by defined search strategies and to store and retrieve previously answered questions. To do this efficiently, an easy-to-use, flexible and reliable drug information database is necessary. METHODS: We designed and implemented an Intranet-based drug information database for a major university hospital in Germany. The overall design and the technical details of its design are discussed. We developed a generic, XML-based data model for pharmaceutical inquiries including a MeSH-oriented system of 99 pharmaceutical qualifiers to enable efficient indexing of questions and the searching of indexed questions. RESULTS: The system provides query statistics and various search algorithms. The software implementation takes into account recent FDA recommendations for software used in clinical trials; internal review for quality control is supported. The database currently consists of 4224 records after 3.5 years of operation. Each inquiry consists of 50 items, 18 of 50 are categorized; 135 text elements support data entry. Our evaluation is focused on technical feasibility, user acceptance and query patterns. CONCLUSION: The intensive use and widespread acceptance of the database indicates a need for a computerized drug information system and suggests that Intranet technology can perform this task.

Abstracting and Indexing↗

PubMed2003

Interferon-alpha disables dendritic cell precursors: dendritic cells derived from interferon-alpha-treated monocytes are defective in maturation and T-cell stimulation.

Dendritic cells (DC) can be derived from monocytes in vitro by culture with granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4). It is unknown whether this regimen reflects DC differentiation from blood precursors under physiological conditions. Induction of DC development from monocytes by interferon-alpha (IFN-alpha) may occur in vivo during infection or inflammation and thus may represent a more physiological approach to DC differentiation in vitro. Here, we show that incubation of GM-CSF-cultured monocytes with IFN-alpha does not induce DC differentiation: cells maintain their original phenotype and cytokine secretion pattern. Even after stimulation with pro-inflammatory or T-cell-derived activation signals, IFN-alpha-treated monocytes do not develop DC characteristics. Addition of IL-4 during stimulation of IFN-alpha-treated monocytes results in the rapid development of DC-like cells expressing co-stimulatory molecules, CD83 and chemokine receptor CCR7, indicating that some degree of developmental plasticity is preserved. However, DC pre-activated with IFN-alpha are less effective in inducing allogeneic or antigen-specific autologous T-cell proliferation, produce less IL-12 and express lower levels of CCR7 compared to DC generated by culture with GM-CSF and IL-4. Incubating GM-CSF-cultured monocytes simultaneously with IFN-alpha and IL-4 does not affect phenotypic maturation of DC, but reduces IL-12 production upon pro-inflammatory activation. We conclude that: (1) IFN-alpha fails to induce DC differentiation and thus cannot replace IL-4 in generating DC from monocytes in vitro; and (2) the presence of IFN-alpha prior to or during differentiation of DC from monocyte precursors alters their response to maturation stimuli and may affect their capacity to stimulate T helper type 1 immune responses in vivo.

Cell Differentiation↗

PubMed2003

Recent advances in immunostimulatory CpG oligonucleotides.

The vertebrate immune system has evolved a mechanism to detect CpG motifs within microbial DNA (CpG DNA). Synthetic oligonucleotides containing CpG motifs (CpG ODNs) are potent immunomodulatory molecules and outstanding vaccine adjuvants. A number of recent findings have greatly improved our understanding of the biology of CpG DNA, and the immunological effects of CpG DNA are now recognized to be distinct in mouse and human. The plasmacytoid dendritic cell (PDC) was identified to play a pivotal role in mediating CpG-induced immune responses. So far, the B-cell is the only other immune cell subset in humans besides the PDC, equipped with the toll-like receptor-9 to detect CpG motifs. The information on these two prime CpG-sensitive cells has allowed the identification of novel CpG ODNs with distinct functional activity. Together with exciting contributions from animal studies, the way seems to be paved for the successful clinical development of this novel class of molecular therapeutics.

Adjuvants, Immunologic↗

PubMed2002

Peritumoral CpG DNA elicits a coordinated response of CD8 T cells and innate effectors to cure established tumors in a murine colon carcinoma model.

The immune system of vertebrates is able to detect bacterial DNA based on the presence of unmethylated CpG motifs. We examined the therapeutic potential of oligodeoxynucleotides with CpG motifs (CpG ODN) in a colon carcinoma model in BALB/c mice. Tumors were induced by s.c. injection of syngeneic C26 cells or Renca kidney cancer cells as a control. Injection of CpG ODN alone or in combination with irradiated tumor cells did not protect mice against subsequent tumor challenge. In contrast, weekly injections of CpG ODN into the margin of already established tumors resulted in regression of tumors and complete cure of mice. The injection site was critical, since injection of CpG ODN at distant sites was not effective. Mice with two bilateral C26 tumors rejected both tumors upon peritumoral injection of one tumor, indicating the development of a systemic immune response. The tumor specificity of the immune response was demonstrated in mice bearing a C26 tumor and a Renca tumor at the same time. Mice that rejected a tumor upon peritumoral CpG treatment remained tumor free and were protected against rechallenge with the same tumor cells, but not with the other tumor, demonstrating long term memory. Tumor-specific CD8 T cells as well as innate effector cells contributed to the antitumor activity of treatment. In conclusion, peritumoral CpG ODN monotherapy elicits a strong CD8 T cell response and innate effector mechanisms that seem to act in concert to overcome unresponsiveness of the immune system toward a growing tumor.

Animals↗

PubMed2002

Quantitative expression of toll-like receptor 1-10 mRNA in cellular subsets of human peripheral blood mononuclear cells and sensitivity to CpG oligodeoxynucleotides.

The Toll-like receptor (TLR)9 is critical for the recognition of immunostimulatory CpG motifs but may cooperate with other TLRs. We analyzed TLR1-10 mRNA expression by using quantitative real-time PCR in highly purified subsets of human PBMC and determined the sensitivity of these subsets to CpG oligodeoxynucleotides (ODN). TLR1 and TLR6 were expressed in all cell types examined. TLR10 was highly expressed in B cells and weakly expressed in plasmacytoid dendritic cells (PDC). High expression of TLR2 was characteristic for monocytes. PDC and B cells expressed marked levels of TLR7 and TLR9 and were directly sensitive to CpG ODN. In CpG ODN-stimulated PDC and B cells, TLR9 expression rapidly decreased, as opposed to TLR7, which was up-regulated in PDC and decreased in B cells. In monocytes, NK cells, and T cells, TLR7 was absent. Despite low expression of TLR9, monocytes, NK cells, and T cells did not respond to CpG ODN in the absence of PDC but were activated in the presence of PDC. In conclusion, our studies provide evidence that PDC and B cells, but not monocytes, NK cells, or T cells, are primary targets of CpG ODN in peripheral blood. The characteristic expression pattern of TLR1-10 in cellular subsets of human PBMC is consistent with the concept that TLR9 is essential in the recognition of CpG ODN in PDC and B cells. In addition, selective regulation of TLR7 expression in PDC and B cells by CpG ODN revealed TLR7 as a candidate TLR potentially involved in modulating the recognition of CpG motifs.

Adjuvants, Immunologic↗

PubMed2002

Apoptotic pancreatic tumor cells are superior to cell lysates in promoting cross-priming of cytotoxic T cells and activate NK and gammadelta T cells.

Tumor vaccines using dendritic cells (DCs) have been shown to induce antitumor CTL responses. The choice of the tumor antigen preparation used for DC loading is still an unresolved issue. We compared DCs pulsed with cell lysates, whole apoptotic tumor cells or their supernatants of the HLA-A2(+) human pancreatic carcinoma cell line Panc-1 for their capacity to activate T cells. Monocyte-derived DCs from HLA-A2(+) donors were pulsed with tumor antigen, matured subsequently, and cocultured with autologeous peripheral blood mononuclear cells. After three weekly restimulations with DCs, T-cell activation was assessed by intracellular IFN-gamma staining and cytotoxicity assays. Compared with lysate, pulsing DCs with the supernatant of apoptotic tumor cells induced a higher frequency of activated CTLs and T-helper cells, as well as an enhanced MHC class I-restricted tumor cell lysis. No activation of natural killer (NK) or gammadelta T cells was detected. Pulsing DCs with whole apoptotic tumor cells induced an even more pronounced lytic effect. However, in this case, MHC class-I blocking was only partially effective, and unrelated cell lines were also killed. IFN-gamma staining revealed activation of CTLs and T-helper cells, as well as NK and gammadelta T cells. Trans-well cultures of NK cells, apoptotic tumor cells, and DCs showed that NK cell activation was dependent on direct cell-to-cell contact with tumor cells and the presence of interleukin-12 produced by DCs. These results indicate that the choice of antigen preparation is a critical determinant in the induction of antitumor immunity. Tumor vaccines consisting of DCs and apoptotic tumor cells may be able to activate CTLs, as well as effector cells of the innate immune system.

Antigens, Neoplasm↗

PubMed2002

Determination of thiopurine S-methyltransferase phenotype using thin-layer chromatography and quantitative scanning.

OBJECTIVE: To develop a non-high-performance liquid chromatography method for the determination of thiopurine- S-methyltransferase (TPMT) phenotype using thin-layer chromatography and quantitative scanning. METHODS: TPMT reaction was performed using a radiochemical assay. The reaction product [(14)C]-6-methylmercaptopurine was separated using thin-layer chromatography and quantified by means of radioactive scanning. Day-to-day variance was determined to validate results. RESULTS: Determination of TPMT phenotype using thin-layer chromatography and quantitative scanning is reliable (day-to-day variance 8.5+/-1.7%, mean+/-SEM). Mean TPMT activity in 314 randomly selected patient samples was 11.8+/-3.3 units/ml red blood cells (mean+/-SD, range 3.5-25 units/ml). CONCLUSION: We developed a new assay variant for the determination of TPMT phenotype that is easy to perform, reliable and reduces production of radioactive waste. This may lead to more frequent pretreatment determination of TPMT phenotype and increase drug safety and efficacy by individualising thiopurine doses.

Carbon Radioisotopes↗

PubMed2002

Combined dendritic cell- and CpG oligonucleotide-based immune therapy cures large murine tumors that resist chemotherapy.

The use of dendritic cells (DC) loaded with tumor antigen is one of the most advanced approaches in cancer immunotherapy. CpG motifs within microbial DNA detected by toll-like receptor 9 are responsible for the favorable properties of CpG oligodeoxynucleotides (ODN) as immune modulators. In this study, mature antigen-pulsed DC or peritumoral injections of CpG ODN, both effective for the treatment of small established tumors, were almost ineffective against large established tumors (1-cm diameter) in a syngeneic murine colon carcinoma model. For large tumors, the antitumor activity of mature antigen-pulsed DC was strongly increased by coinjection of CpG ODN, resulting in a transient control of tumor growth. Rejection of large tumors and long-term cure of mice was achieved by combining injection of antigen-pulsed DC plus CpG ODN at a site distant to the tumor with peritumoral injections of CpG ODN. Depletion of CD8 T cells abrogated the therapeutic activity. Large numbers of DEC-205-positive DC infiltrated the tumor in treated mice. Therapy with 5-fluorouracil and leucovorin was unable to control tumors of the same size. In conclusion, we demonstrate that the immune system, provided that appropriate stimulation with DC and CpG ODN is given, has the potential to cure animals of large solid tumors in situations where even chemotherapy is not efficient.

Adjuvants, Immunologic↗