技术资料

Abnormal differentiation of myeloid cells is one of the hallmarks of cancer. However,the molecular mechanisms of this process remain elusive. In this study,we investigated the effect of tumor-derived factors on Janus kinase (Jak)/STAT signaling in myeloid cells during their differentiation into dendritic cells. Tumor cell conditioned medium induced activation of Jak2 and STAT3,which was associated with an accumulation of immature myeloid cells. Jak2/STAT3 activity was localized primarily in these myeloid cells,which prevented the differentiation of immature myeloid cells into mature dendritic cells. This differentiation was restored after removal of tumor-derived factors. Inhibition of STAT3 abrogated the negative effects of these factors on myeloid cell differentiation,and overexpression of STAT3 reproduced the effects of tumor-derived factors. Thus,this is a first demonstration that tumor-derived factors may affect myeloid cell differentiation in cancer via constitutive activation of Jak2/STAT3. View Publication

The ability of acute myeloid leukemic (AML) blasts to differentiate into leukemic dendritic cells (DC) thus acquiring the potential to present known and unknown leukemic antigens efficiently,holds promise as a possible new treatment for AML patients with minimal residual disease. Recent advances in culture methods have made the clinical use of leukemic DC feasible. However,additional measures appear to be essential in order to potentiate vaccines and to overcome the intrinsic tolerant state of the patients immune system. This review describes ways to improve AML-DC vaccines and discusses critical aspects concerning the development of clinical vaccination protocols. View Publication

Acute lymphoblastic leukemia (ALL) still frequently recurs after hematopoietic stem cell transplantation (HSCT),underscoring the need to improve the graft-versus-leukemia (GvL) effect. Natural killer (NK) cells reconstitute in the first months following HSCT when leukemia burden is at its lowest,but ALL cells have been shown to be resistant to NK cell-mediated killing. We show here that this resistance is overcome by NK cell stimulation with TLR-9-activated plasmacytoid dendritic cells (pDCs). NK cell priming with activated pDCs resulted in TRAIL and CD69 up-regulation on NK cells and IFN-γ production. NK cell activation was dependent on IFN-α produced by pDCs,but was not reproduced by IFN-α alone. ALL killing was further enhanced by inhibition of KIR engagement. We showed that ALL lysis was mainly mediated by TRAIL engagement,while the release of cytolytic granules was involved when ALL expressed NK cell activating receptor ligands. Finally,adoptive transfers of activated-pDCs in ALL-bearing humanized mice delayed the leukemia onset and cure 30% of mice. Our data therefore demonstrate that TLR-9 activated pDCs are a powerful tool to overcome ALL resistance to NK cell-mediated killing and to reinforce the GvL effect of HSCT. These results open new therapeutic avenues to prevent relapse in children with ALL. View Publication

Granulomas are innate sequestration responses that can be modified by superimposed acquired immune mechanisms. The present study examined the innate stage of pulmonary granuloma responses to bead-immobilized Th1- and Th2-inducing pathogen antigens (Ags),Mycobacteria bovis purified protein derivative (PPD) and Schistosoma mansoni soluble egg Ags (SEA). Compared to a nonpathogen Ag,PPD and SEA bead elicited larger lesions with the former showing accelerated inflammation. Temporal analyses of cytokine and chemokine transcripts showed all Ag beads induced tumor necrosis factor-alpha mRNA but indicated biased interleukin (IL)-1,IL-6,and IL-12 expression with PPD challenge. All beads elicited comparable levels of CXCL9,CXL10,CCL2,CCL17,and CCL22 mRNA,but PPD beads caused biased CXCL2 CXCL5,CCL3,and CCL4 expression whereas both pathogen Ags induced CCL7. Immunohistochemical,electron microscopic,and flow cytometric analyses showed that Ag beads mobilized CD11c+ dendritic cells (DCs) of comparable maturation. Transfer of DCs from PPD Ag-challenged lungs conferred a Th1 anamnestic cytokine response in recipients. Surprisingly,transfer of DCs from the helminth SEA-challenged lungs did not confer the expected Th2 response,but instead rendered recipients incapable of Ag-elicited IL-4 production. These results provide in vivo evidence that lung DCs recruited under inflammatory conditions favor Th1 responses and alternative mechanisms are required for Th2 commitment. View Publication

Histone deacetylase inhibitors (HdI) could potentially improve the differentiation of leukemic dendritic cells (DC). Therefore,bone marrow samples from 100 children with acute lymphoblastic leukemia (ALL) were cultured in the cytokines TNF-alpha,GM-CSF,c-kit ligand,and fetal liver tyrosine kinase 3 ligand,with or without IL-3 and -4 and after administration of HdI valproic acid (VAL),suberoylanilide hydroxamic acid (SAHA),isobutyramid,or trichostatin A. Among the tested samples,25 were positive for the chromosomal translocation t(12;21),encoding the fusion gene translocation ETS-like leukemia/acute myeloid leukemia 1 (TEL/AML1). SAHA increased CD83 expression of TEL/AML1-positive blasts in conditions without ILs,and SAHA and VAL increased the number of CD86(+)80(-) cells in the presence of ILs. VAL and isobutyramid supported the allostimulatory capacities of TEL/AML1-positive,leukemic DC; VAL and SAHA reduced those of TEL/AML1-negative DC. Cytotoxic T cells sensitized with leukemic DC produced more IFN-gamma and TNF-alpha upon presentation of the TEL/AML1 peptide. They also induced the cytotoxic lysis of nondifferentiated blasts,which was enhanced when TEL/AML1-positive DC had developed after addition of VAL or SAHA. Therefore,the use of HdI in the differentiation of leukemic DC from patients with TEL/AML1-positive ALL is recommended. View Publication