B7-H1 up-regulation on dendritic-like leukemia cells suppresses T cell immune function through modulation of IL-10/IL-12 production and generation of Treg cells.

Dendritic-like leukemia cells (DLLC) originating from leukemic cells could potentially induce a T cell-mediated anti-leukemia immune response. It has been demonstrated that B7-H1, a newly identified homologue of CD80/CD86, is abundant in human carcinomas and dendritic cells (DC), can exert co-stimulatory and immune regulatory functions. We demonstrated that B7-H1 was significantly expressed on AML cells and was strongly enhanced after differentiation to DLLC.

Effects of human mesenchymal stem cells on the differentiation of dendritic cells from CD34+ cells.

Mesenchymal stem cells (MSCs) have profound immunomodulatory functions both in vitro and in vivo. However, their effects on the differentiation of dendritic cells (DCs) are unknown. In this study, we employed an in vitro model to investigate the effects of human MSCs on the development of DCs.

[Comparison of expanding dendritic cells derived from cord blood and mobilized peripheral blood by two-step culture method].

To compare the expansion efficiency and function of dendritic cells derived from CB-CD34+ cells and MPB-CD34+ cells by using two-step culture method, enriched CB-CD34+ cells or MPB-CD34+ cells with immunoadsorption were primarily cultured in the presence of FL, SCF, TPO, GM-CSF for 10 days, and then further cultured with a combination of GM-CSF, IL-4, TNF-alpha, CD40Ab and PGE2 to induce DC. The DC phenotypes were detected by flow cytometry, the expansion efficiency and cell function were evaluated by mix-lymphocyte reaction (MLR), IL-12 level was detected by using ELISA and the chemotactic function mediated by secondary lymphoid tissue chemokine (SLC) was determined with Transwell plate. The results indicated that after 10 days of expansion, there were no significant difference in the percentage of CD14+CD1a- cells between CB and MPB [(40.

[Anti-leukemia immunity induced by dendritic cells fused with L615 tumor cells].

This study was aimed to investigate the specific anti-L615 leukemia cell immunity induced by L615/DC fused cell vaccine in vivo and in vitro. BM-derived DCs were generated from bone marrow of 615 mice by culturing for 9 - 10 days in culture medium supplemented with GM-CSF and IL-4. Irradiated L615 tumor cells were fused with DC by using PEG to form fused cell vaccine, with which 615 mice were immunized.

[Induction of efficient T-cell immunity against autologous leukemia cells by dendritic cells pulsed with the leukemia cell total RNA].

Objective: To assess the feasibility and efficiency of eliciting leukemia-specific T cell responses in acute myeloid leukemia patients in complete remission (AML-CR) in vitro by dendritic cells (DC) pulsed with the leukemia cells total RNA.

Methods: The immature DCs were generated from the adherent bone marrow mononuclear cell in vitro in the presence of combined cytokines (GM-CSF 100 ng/ml, IL-4 500 U/ml), and pulsed with total RNA isolated from autologous leukemic cells by cationic lipid 1,2-dioleoyloxy-3-trimethyl ammonium propane (DOTAP) at day 5 of culture. Then the cells were incubated for another 24 h in a medium containing 10 ng/ml of TNF-alpha for maturation of DC.

Effects of allogeneic bone marrow-derived mesenchymal stem cells on T and B lymphocytes from BXSB mice.

Bone marrow-derived mesenchymal stem cells (bMSCs) can differentiate into a number of different cell/tissue types, and also possess immunoregulatory functions. The present study was undertaken to elucidate the exact immunoregulatory effects of allogeneic bMSCs on T- and B-lymphocyte proliferation, activation, and function maturation of BXSB mice, which has been considered as a experimental model for human systemic lupus erythematosus (SLE). We determined that bMSCs from BALB/c mice had inhibitory effects on BXSB mice T-lymphocyte proliferation, but no inhibitory effect on their activation.

Engrafted bone marrow-derived flk-(1+) mesenchymal stem cells regenerate skin tissue.

Stem cell plasticity has created great interest because of its potential therapeutic application in degenerative or inherited diseases. Transplantation of bone marrow-derived stem cells was shown to give rise to cells of muscle, liver, nerve, endothelium, epithelium, and so on. But there are still disputes about stem cell plasticity, especially concerning the contribution of bone marrow-derived cells to skin cells.

[Inhibition effect of bone marrow mesenchymal stem cells on T-lymphocyte proliferation through up-regulation of CD8+CD28- T cells].

The aim of this study was to explore effect of CD8+CD28- T-lymphocyte in the inhibition of mesenchymal stem cells (MSC) on T-lymphocyte proliferation. T cells were harvested by using nylon column and CD8+ T cells were sorted by magnetic beads; the T-lymphocyte proliferation in the presence of PHA was evaluated by MTT; the proportion of CD8+CD28- T cells was assayed by fluorescence-activated cell sorter (FACS). The results showed that MSC inhibited T-lymphocyte proliferation and the inhibitory effect depended on the amount of MSC; the data of FACS indicated that in the CD8+ T cells co-cultured with MSC, CD8+CD28- T cells were up-regulated significantly, compared with the non-treated CD8+ T cells.

Allogeneic bone marrow-derived flk-1+Sca-1- mesenchymal stem cells leads to stable mixed chimerism and donor-specific tolerance.

Objective: To investigate the possibility of flk-1+Sca-1- bone marrow-derived mesenchymal stem cells (bMSCs) to induce stable mixed chimerism and donor-specific graft tolerance.

Methods: Allogeneic flk-1+Sca-1- bMSCs and syngeneic bone marrow (BM) cells were cotransplanted into lethally irradiated (8.5 Gy) recipient mice.

Effects of mesenchymal stem cells on differentiation, maturation, and function of human monocyte-derived dendritic cells.

Mesenchymal stem cells (MSCs) reportedly inhibit the mixed lymphocyte reaction. Whether this effect is mediated by dendritic cells (DCs) is still unknown. In this study, we used an in vitro model to observe the effects of MSCs and their supernatants on the development of monocyte-derived DCs.

[Coculture of dendritic cell with cytokine-induced killer results in a significant increase in cytotoxic activity of CIK to tumor cells in vitro and in vivo].

Objective: To explore whether coculture of dendritic cells (DC) with cytokine-induced killer (CIK) lead to an increase of cytotoxicity against tumor cells in vitro and in vivo.

Methods: DC and CIK were prepared from human peripheral blood mononuclear cells (PBMC) by conventional methods, the DC pulsed with or without NB4 leukemia cell lyses (LCL) was cocultured with the CIK (LCL-DC + CIK and DC + CIK), CIK was used as control. Cells phenotypes were analyzed by flow cytometry, secretion of IFN-gamma was determined by ELISPOT assay, and cytotoxicity was assayed in vitro with (51)Cr-release assay.

[Preliminary study on extensive amplification of human dendritic cells differentiated from cord blood CD34+ progenitor cells by two-step culture].

Objective: To Explore a two-step culture system to generate a large number of dendritic cells (DC) differentiated from cord blood (CB) CD(34)(+) cells.

Methods: Enriched CB CD(34)(+) cells with immunoadsorption were primarily cultured in the presence of stem cell factor (SCF), Flt-3 ligand (FL), thrombopoietin (Tpo) and interleukin-3 (IL-3) for 7 (group I), 10 (group II) or 14 days (group III) respectively, and then further cultured with GM-CSF, IL-4 and TNF-alpha for 5 - 8 days to induce DC. The expansion and cell function were evaluated by flow cytometry (FCM) and mix-lymphocyte reaction (MLR), and detection of IL-12 in the supernatant by using ELISA.

Induction of T-cell immunity against leukemia by dendritic cells pulsed with total RNA isolated from leukemia cells.

Objectives: To assess the feasibility and efficacy of eliciting leukemia-specific T-cell responses in syngeneic mice in vitro and in vivo using dendritic cells (DCs) pulsed with total RNA from leukemia cells.

Methods: DCs generated from bone marrow culture in vitro in the presence of combined cytokines were pulsed with cellular total RNA isolated from cultured L615 cells by cationic lipid 1,2-dioleoyloxy-3-(trimethylammonium) propane (DOTAP). T-cell responses were evaluated by in vitro proliferation, and cytotoxicity assay.

[Dendritic cells (DC) induced from acute myeloid leukemia (AML) cells with cytokine cocktails].

Objectives: To explore the feasibility of DC being in vitro induced from AML cells with cytokine cocktails and their biological properties.

Methods: AML cells were cultured in either presence or absence of cytokine cocktails. DC were studied for morphology, and cytochemical and immunofluorescent staining.