Cellular immune suppression in cancer patients and its implication for dendritic cell therapy

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Background: The treatment of human cancer with monocyte-derived dendritic cells (MoDC) is a promising and innovative approach. However, many of the treated patients fail to respond to therapy. The reduced clinical antitumor response may be due to an inflammatory immune-suppressive tumor microenvironment. Regulatory T-cells (T-reg) and other cells with suppressive potential can promote an immune suppressive tumor microenvironment and thus play an important role in regulation of the immune response. Methods: Whole blood from n=100 cancer patients with various tumor types and from n=30 healthy donors were analysed by flow cytometry. CD4+ lymphocytes with immune suppressive potential were characterized by analysing the expression of CD25, CD39, CD127. Results: We found a significantly higher proportion of CD25+/CD39+ and of CD25+/CD127low T-helper cells in the blood of cancer patients as compared to healthy donors. This may indicate two different types of T-reg involved in immune suppression in cancer patients. Treatment of patients with metronomic chemotherapy induced a down-regulation of these cells. Interestingly, we found a subpopulation of cells within the lymphocyte gate characterized by CD2high and CD86 expression in cancer patients with very advanced stage, similar to such normally found in hemaphagocytic lymphohistiocytosis (HLH) patients characterized by exceeding high plasma concentration of IFN-g and IL-10 (Schneider et al. 2002). These cells can be down-regulated by treatment with a tetradecapeptide (Ezrin) known to act as an immune modulator with anti-viral activity leading to reduction of inflammatory cytokines. Conclusions: An efficient induction of a clinical antitumor response requires both a polarization of MoDC in a TH1 direction as well as changing an immune suppressive tumor microenvironment. For the first time, we identified HLH associated cells in advanced cancer patients. As HLH is characterized by hyperinflammation, these cells may indicate an inflammatory tumor microenvironment. Thus, anti-inflammatory therapy should be considered as co-treatment with immunotherapy with dendritic cells for down-regulation of immune suppressive cells (T-reg, CD2high/CD86+ cells) to promote a clinical antitumor response.

No significant financial relationships to disclose.

Dendritic cell therapy in glioblastoma multiforme

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Background: Malignant brain tumors belong to the tumors with unfavorable prognosis. The most aggressive form, glioblastoma multiforme (GBM WHO grade IV glioma), is categorized as incurable with median survivals less than 12–18 months and 90–95% of patients surviving less than 2 years. Here we show that immunotherapy with monocyte-derived dendritic cells (MoDC) can induce a clinical response in advanced GMB, especially when combined with the non human pathogenic oncolytic virus NDV (New Castle Disease Virus). Methods: After isolating monocytes from peripheral blood of n=21 patients dendritic cells were generated ex vivo in the presence of recombinant cytokines (IL-4, GM-CSF) and 2,5% autologous serum. If tumor tissue was available the MoDC were primed on day 5 with tumor- lysate and co-cultured with poly:IC and IFN-alpha. The MoDC were harvested on day 7 of culture and administered to the patients, intradermally. In 5 patients NDV was added to the MoDC for one hour prior to administration. These patients received an infusion with NDV one day before vaccination. Results: We were able to induce a clinical response in 33% (n=7) of the treated patients. The median survival after onset of DC-therapy was 10 months. With respect to primary diagnosis the median survival was 19 months with 1- and 2-years survival rates of 81% and 14%, respectively. Improvement of the clinical response can be observed by combination of NDV. None of the 5 patients treated with this combination therapy died of the disease (9–19 months after primary diagnosis). Three of them (60%) show a response with 2 clear partial remissions (40%). Conclusions: Taken together, a dendritic-cell based therapy can be successful in the treatment of GBM. Enhancement of the therapeutically outcome can be induced by a combination therapy with New Castle Disease Virus leading to the suggestion that there may be an interaction between the dendritic cells and the NDV.

No significant financial relationships to disclose.

Golgi retention of human protein NEFA is mediated by its N-terminal Leu/Ile-rich region

The subcellular localization of the human Ca(2+)-binding EF-hand/leucine zipper protein NEFA was studied in HeLa cells by immunofluorescence microscopy. Double immunostaining using mouse anti-NEFA monoclonal antibody 1H8D12 and rabbit anti-ERD2 polyclonal antibody proved that NEFA is localized in the Golgi apparatus. The result was confirmed by the expression of NEFA-green fluorescent protein (GFP) fusion protein in the Golgi in the same cell line. Cycloheximide treatment proved NEFA to be a Golgi-resident protein. Seven NEFA deletion mutants were constructed to ascertain the peptide region relevant for Golgi retention. The expression of each NEFA-GFP variant was detected by fluorescence microscopy and immunoblotting. Only the DeltaN mutant, lacking the N-terminal Leu/Ile-rich region, failed to be retained in the Golgi after cycloheximide treatment. The other six deletion mutants in which either the basic region, the complete EF-hand pair domain, the two EF-hand motifs separately, the leucine zipper and the leucine zipper plus the C-terminal region is deleted, were localized to the Golgi. The peptide sequence within the Leu/Ile-rich region is discussed as a novel Golgi retention motif.