Similar immune responses and antitumor effects of murine dendritic cells loaded with either exogenous or endogenous-synthesized protein.

Conceptually, dendritic cells (DCs) take up and process exogenous antigens that are presented on MHC (major histocompatibility complex) class II molecules to stimulate CD4+ T cells, and present endogenously-produced proteins to CD8+ T cells through an MHC class I-dependent pathway. In this study, we compared the antitumor effects generated in vivo after vaccinations with DCs either loaded with exogenous protein (DCs-exo) or presenting antigens derived from endogenous-synthesized protein (DCs-endo). We used the murine MC26SC31 colon carcinoma cell line expressing on the cell surface the human CD4 (hCD4) molecule as a model tumor-associated antigen (TAA).

Cellular but not humoral immune responses generated by vaccination with dendritic cells protect mice against leukaemia.

Dendritic cells (DC) are extremely efficient at generating both prophylactic and therapeutic anti-tumour immunity. We aimed to analyse the respective roles of humoral and cellular immune responses generated in mice vaccinated with bone marrow (BM)-derived DC in terms of in vivo anti-leukaemia effect. We used the murine L1210 B lymphocytic leukaemia genetically modified to express on the cell surface of human CD4 (hCD4) (L1210/hCD4) as a model tumour-associated antigen (TAA).

Immunophenotypical and functional heterogeneity of dendritic cells generated from murine bone marrow cultured with different cytokine combinations: implications for anti-tumoral cell therapy.

Dendritic cells (DC) are professional antigen-presenting cells that can be used as immune adjuvant for anti-tumoural therapies. This approach requires the generation of large quantities of DC that are fully characterized on the immunophenotypical and functional levels. In a murine model, we analysed the in vitro effects of granulocyte-macrophage colony-stimulating factor (GM-CSF) alone or combined with interleukin-4 (IL-4) or Flt3 ligand (Flt3-L) on the number, immunophenotype and functions of bone marrow-derived DC.

High level of retrovirus-mediated gene transfer into dendritic cells derived from cord blood and mobilized peripheral blood CD34+ cells.

Dendritic cells (DCs), the most potent antigen-presenting cells, can be generated from CD34+ hematopoietic stem cells and used for generating therapeutic immune responses. To develop immunotherapy protocols based on genetically modified DCs, we have investigated the conditions for high-level transduction of a large amount of CD34+-derived DCs. Thus, we have used an efficient and clinically applicable protocol for the retroviral transduction of cord blood (CB) or mobilized peripheral blood (MPB) CD34+ cells based on infection with gibbon ape leukemia virus (GALV)-pseudotyped retroviral vectors carrying the nls-LacZ reporter gene.

The tetrapeptide AcSDKP reduces the sensitivity of murine CFU-MK and CFU-GM progenitors to aracytine in vitro and in vivo.

The tetrapeptide Acetyl-Ser-Asp-Lys-Pro (AcSDKP) has been described as an inhibitor of CFU-S entry into DNA synthesis; as a result, its administration can protect mice against lethal doses of cytosine arabinoside (Ara-C). In the present study, we tested the protective effect of AcSDKP on CFU-MK and CFU-GM progenitor cells in mice treated at lower doses of Ara-C more relevant to human clinical situations. Firstly, we report for the first time that in vitro pre-incubation of murine BM MNC with AcSDKP at concentrations of 10(-10) and 10(-9) M for 48 h decreased CFU-MK, in parallel to CFU-GM, progenitor growth.

Dendritic cells route human immunodeficiency virus to lymph nodes after vaginal or intravenous administration to mice.

We have developed a murine model to study the involvement of dendritic cells (DC) in human immunodeficiency virus (HIV) routing from an inoculation site to the lymph nodes (LN). Murine bone marrow-derived DC migrate to the draining LN within 24 h after subcutaneous injection. After incubation of these cells with heat-inactivated (Hi) HIV type 1 (HIV-1), HIV RNA sequences were detected in the draining LN only.

Implication of macrophage inflammatory protein-1alpha in the inhibition of human haematopoietic progenitor growth by dengue virus.

The mechanisms were investigated of haematopoietic progenitor growth inhibition, observed after in vitro infection of cord blood mononuclear cells (CBMNC) by a clinical isolate of dengue 3 (29-56DSS). The level of virus replication was not different when CBMNC were inoculated with 29-56DSS compared with a prototype strain of dengue 3 (H-87) which had no inhibitory effect. An inhibitory effect was also observed when cell-free and heat-inactivated supernatants from 29-56DSS cultures, but not from H-87 cultures, were added to cultures of normal CBMNC, suggesting an indirect mechanism via the release of soluble suppressive factor(s).

Comparison of the effects of AcSDKP, thymosin beta4, macrophage inflammatory protein 1alpha and transforming growth factor beta on human leukemic cells.

We have compared the effects of AcSDKP, Thymosin beta4 (Tbeta4), MIP1alpha and TGFbeta on acute myeloid leukemia (AML) and B-lineage acute lymphoid leukemia (B-ALL) cells using liquid cultures in the presence of GM-CSF, IL-3 and SCF for AML cells and IL-3 and IL-7 for ALL cells. Each molecule was added daily and cell proliferation was evaluated on day 3 by thymidine incorporation. Whereas TGFbeta was found inhibitory in all the AML and B-ALL cases studied, MIP1alpha was inhibitory in 6/12 AML cases and had no effect on B-ALL cells.

High-level gene transfer to cord blood progenitors using gibbon ape leukemia virus pseudotype retroviral vectors and an improved clinically applicable protocol.

The best methods for transducing hematopoietic progenitor cells usually involve either direct co-cultivation with virus-producing cells or human stromal supportive cells. However, these methods cannot be safely or easily applied to clinical use. Therefore, we aimed at improving retrovirus-mediated gene transfer into hematopoietic progenitors derived from cord blood CD34+ cells using viral supernatant to levels achieved at least with direct co-cultivation and under conditions that are suitable for clinical applications.

The influence of interleukin (IL)-4, IL-13, and Flt3 ligand on human dendritic cell differentiation from cord blood CD34+ progenitor cells.

Culturing cord blood CD34+ cells with granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor (TNF)-alpha for 12 days, and stem cell factor (SCF) for 5 days, resulted in a 40- +/- 26-fold expansion in cell numbers, with 38 +/- 20% dendritic cells (DCs). Interleukin (IL)-4 and IL-13, which share properties, were examined first. Adding either one to the former baseline condition beginning on day 0 halved cell growth while the percentage of DCs increased to 60-70%, resulting in unchanged DC yields.

Dengue virus inhibits human hematopoietic progenitor growth in vitro.

Dengue disease, whether it be classical dengue fever (DF), dengue hemorrhagic fever (DHF), or dengue shock syndrome (DSS), is frequently associated with hematologic disorders. The underlying cause of these abnormalities is unknown. To determine if an inhibitory effect on human hematopoietic progenitor growth can be observed, normal cord blood mononuclear cells were exposed to low-passaged clinical isolates from DF, DHF, and DSS patients and to the prototype strain of dengue-3 virus (H-87).

The effect of in vitro human immunodeficiency virus infection on dendritic-cell differentiation and function.

CD1a+ dendritic cells (DC) differentiate from a major population of nonadherent CD13(hi)lin- cells that appear when human cord blood CD34+ hematopoietic progenitor cells are cultured with stem-cell factor, granulocyte/macrophage (MA) colony-stimulating factor, and tumor necrosis factor-alpha (TNF-alpha) for 5 days. CD13hilin- cells, which also comprise MA and granulocyte precursors, are CD4+ and can thus be targets of human immunodeficiency virus (HIV). Low replication was noted when these day 5 cells were infected with lymphotropic HIV-1LA1 (p24: < or = 4 ng/mL on day 8 postinfection [PI]), while high virus production occurred with MA-tropic HIV-1Ba-L, HIV-1Ada, or HIV-1-m-n.

In vivo effect of platelet factor 4 (PF4) and tetrapeptide AcSDKP on haemopoiesis of mice treated with 5-fluorouracil.

In vivo effects of platelet factor 4 (PF4) and tetrapeptide N-acetyl-Ser-Asp-Lys-Pro (AcSDKP) on haemopoietic progenitors were studied in mice treated with 5-fluorouracil (5-FU). The mice were injected with PF4 (40 micrograms/kg) or AcSDKP (4 micrograms/kg) twice at 6 h intervals, and 20 h after the second injection they were given one injection of 5-FU (150 mg/kg). 6, 8 and 13 d later the high proliferative potential-colony forming cell (HPP-CFC), burst-forming unit erythroid (BFU-E), colony forming unit granulocyte-macrophage (CFU-GM) colony forming unit megakaryocyte (CFU-MK), and megakaryocytes (MK) were examined.

Thymosin beta4, inhibitor for normal hematopoietic progenitor cells.

Thymosin beta4 (Tbeta4), isolated from the calf thymus fraction 5, has a ubiquitous localization and plays a pleiotropic role in both the immune and nonimmune systems. Because it contains at its N-terminal end the sequence of a known inhibitor of hematopoiesis, the acetylated tetrapeptide Ac-N-Ser-Asp-Lys-Pro (AcSDKP, Goralatide), we have assayed Tbeta4 on human hematopoietic cells. We demonstrate that it inhibits normal bone marrow progenitor cell growth; indeed, it decreased the growth of both granulo-macrophagic and erythroid progenitors and reduces their percentage in S phase.

Heterogeneity of B lineage acute lymphoblastic leukemias (B-ALL) with regard to their in vitro spontaneous proliferation, growth factor response and BCL-2 expression.

The spontaneous proliferation and the effects of 8 various growth factors (GF) were evaluated on leukemic cells from 27 patients with B-lineage ALL. Two groups of ALLs were distinguished. ALLs from group I (21 patients) exhibited a low spontaneous proliferative rate and were stimulated by IL-3 + IL-7 +/- SCF and/or LIF, while ALLs from group II (6 patients) had a high spontaneous proliferative rate and did no longer require this combination of GFs for proliferation.

Inhibitory peptides in hematopoiesis.

This paper will review the present knowledge on two small chemically unrelated peptides, the pentapeptide pGlu-Glu-Asp-Cys-Lys (pEEDCK) and the tetrapeptide acetyl-N-Ser-Asp-Lys-Pro (AcSDKP, Seraspenide) focusing on 1) their inhibitory effects on normal hematopoiesis, 2) their effect on malignant cells, especially leukemic cells, and 3) their potential clinical use as marrow protectors during cancer therapy.

Comparison of the inhibitory effect of AcSDKP, TNF-alpha, TGF-beta, and MIP-1 alpha on marrow-purified CD34+ progenitors.

The aim of this study was to compare the inhibitory effect of the tetrapeptide AcSDKP, tumor necrosis factor-alpha (TNF-alpha), which contains the sequence of the peptide, transforming growth factor-beta (TGF-beta), and macrophage inflammatory protein-1 alpha (MIP-1 alpha) on sorted CD34+ cells using both proliferation and clonogenic assays. Although a short treatment with any of the molecules decreased the growth of colony-forming unit granulocyte/macrophage (CFU-GM) and burst-forming unit-erythroid (BFU-E) progenitors (except for TNF-alpha as it is a greater inhibitor for CFU-GM), further experiments using a 6-day liquid culture in the presence of a combination of growth factors (recombinant human interleukin-3 [rhIL-3], IL-6, IL-1 beta, GM colony-stimulating factor [GM-CSF], G-CSF, erythropoeitin [Epo], and stem cell factor [SCF]) allowed us to determine a number of differences between their effects: 1) TGF-beta and TNF-alpha induced a stronger decrease in the proliferation and clonogenicity of CD34+ subsets than MIP-1 alpha and AcSDKP, 2) the dose-response curves appeared different, and 3) contrary to TGF-beta and TNF-alpha, AcSDKP and MIP-1 alpha required repeated addition to induce inhibition. Therefore, our data clearly show that while the inhibitory effect of TNF-alpha and AcSDKP appeared to be different, there is a close similarity in the effect of AcSDKP and MIP-1 alpha on normal human progenitor response to the combination of growth factors used.

Tumor necrosis factor alpha (TNF alpha) downregulates c-kit proto-oncogene product expression in normal and acute myeloid leukemia CD34+ cells via p55 TNF alpha receptors.

Tumor necrosis factor alpha (TNF alpha), as a modulator of hematopoiesis, interacts with many growth factor receptors, such as interleukin-3, granulocyte-macrophage colony-stimulating factor (CSF), and granulocyte-CSF receptors. Here, we studied the interactions between TNF alpha and the stem cell factor (SCF) receptor, c-kit, in normal CD34+ hematopoietic progenitors and their leukemic counterpart, ie, acute myeloid leukemic (AML) CD34+ cells coexpressing c-kit antigen. The results showed that (1) incubation of normal bone marrow mononuclear cells with 200 U/mL rhTNF alpha for 20 hours induced a diminution of 31.

Photoprotection of normal human hematopoietic progenitors by the tetrapeptide N-AcSDKP.

The tetrapeptide AcSDKP (Ser-Asp-Lys-Pro) is a reversible inhibitor of normal human hematopoietic progenitor growth. In this paper, we report that preincubation of bone-marrow mononuclear cells (MNC) with AcSDKP at 10(-10) M for 20 hours protects the granulocyte-macrophage colony-forming unit (CFU-GM) progenitors against photofrin II-mediated phototherapy. This protective effect was observed after short-term exposure to photofrin (2.