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PubMed2001

All trans retinoic acid abrogates spontaneous monocytic growth in juvenile chronic myelomonocytic leukaemia.

INTRODUCTION: All trans retinoic acid, the active metabolite of vitamin A, exerts profound effects on cell differentiation. On normal myeloid progenitors, retinoids switch the differentiation program of granulo-macrophagic progenitors towards the granulocytic lineage and consequently reduce CFU-M colony formation. Bone marrow and peripheral blood mononuclear cells from children with Juvenile Chronic Myelomonocytic Leukaemia show typical spontaneous monocytic growth. We questioned whether in this disease, retinoids could switch myelomonocytic growth and inhibit the abnormal CFU-M colony proliferation. METHODS: Ten JCML samples were studied in the presence of ATRA in methyl cellulose colony assay, before (CFU-C) or after (pre-CFU) liquid suspension culture. RESULTS: In vitro characteristics of JCML such as spontaneous monocytic growth in the absence of growth factor was noted in all patients. In the presence of leucocyte-conditioned medium, nine samples showed only CFU-M growth and one sample CFU-GM growth. Incubation with ATRA inhibited CFU-M colony formation in nine cases. Enhancement of granulocytic differentiation (CFU-G) was noted in nine cases. ATRA also inhibited CD34+ JCML monocytic growth and GM-CSF hypersensitivity. CONCLUSION: These data suggest that, in JCML progenitors, retinoid pathways are functional and inhibition of immature monocytic progenitors cells may be achieved with retinoids, without impeding granulocytic cell growth.

Antineoplastic Agents↗
PubMed2002

Usefulness of RA and RO isoforms of common leukocyte antigen (CD45) for early distinction between normal and abnormal promyelocytes.

Normal promyelocytes express CD45RO, while acute promyelocytic leukemia (APL) blasts express CD45RA, both isoforms of common leukocyte antigen with mutually exclusive expression. Here we report a patient with accumulation of promyelocytes in the bone marrow and the diagnostic strategy is described along with the ability to quickly discriminate between normal and abnormal cells using the flow cytometric detection of expression of RA/RO isoforms of CD45.

Bone Marrow Cells↗
PubMed1981

Cyclophosphamide treatment expands the circulating hematopoietic stem cell pool in dogs.

Increased numbers of circulating granulocyte-monocyte precursor cells (CFUc) have been observed in the peripheral blood of man after antineoplastic chemotherapy. We have developed a canine model to study the biologic significance of this phenomenon for hematopoietic reconstitution following hematopoietically lethal exposure to total body irradiation (TBI). After cyclophosphamide administration, a 16-fold expansion of circulating CFUc numbers was observed during the period of rapid leukocyte recovery that occurred after the chemotherapy-induced leukocyte nadir. We had previously noted this association between leukocyte recovery and CFUc expansion in our human studies. After 900 rad TBI hematopoietic reconstitution was attempted with autologous, cryopreserved collections of peripheral blood mononuclear cells obtained either at times of post-cyclophosphamide CFUc expansion (group A, 14 dogs) or without CFUc expansion (group B, 12 dogs). Asd compared to group B collections, group A collections contained 11-fold more CFUc and were 12.5-fold more potent in fostering hematopoietic recovery after TBI. These results suggest that the expansion of CFUc numbers we observed was accompanied by a similar expansion of more primitive hematopoietic stem cell numbers. We conclude that chemotherapy-induced expansion of circulating CFUc numbers appears to be of substantial import in effecting hematopoietic reconstitution--an observation that may be of significance for further studies of autologous hematopoietic reconstitution in man.

Animals↗
PubMed2004

Balance of MafB and PU.1 specifies alternative macrophage or dendritic cell fate.

Macrophages and myeloid dendritic cells (DCs) represent alternative differentiation options of bone marrow progenitors and blood monocytes. This choice profoundly influences the immune response under normal and pathological conditions, but the underlying transcriptional events remain unresolved. Here, we show that experimental activation of the transcription factors PU.1 and MafB in transformed chicken myeloid progenitors triggered alternative DC or macrophage fate, respectively. PU.1 activation also was instructive for DC fate in the absence of cytokines in human HL-60 cell-derived myeloid progenitor and monocyte clones. Differentiation of normal human monocytes to DCs led to a rapid increase of PU.1 to high levels that preceded phenotypic changes, but no MafB expression, whereas monocyte-derived macrophages expressed MafB and only moderate levels of PU.1. DCs inducing levels of PU.1 inhibited MafB expression in monocytes, which appeared to be required for DC specification, since constitutive MafB expression inhibited DC differentiation. Consistent with this, PU.1 directly bound to MafB, inhibited its transcriptional activity in macrophages, and repressed its ability to induce macrophage differentiation in chicken myeloid progenitors. We propose that high PU.1 activity favors DCs at the expense of macrophage fate by inhibiting expression and activity of the macrophage factor MafB.

Animals↗
PubMed2005

Immune characterization of the Lewis rats inoculated with K2 sarcoma cell line and newly derived R5-28 malignant cells.

Sarcoma is a relatively rare malignant disease with high mortality, bad prognosis and response to conventional therapy. Two possible models of this disease were tested: the K2 rat sarcoma cell line, which was described previously, and the new rat R5-28 cell line derived from a spontaneously growing rat neoplasm with sarcoma morphology. While all rats inoculated with K2 cells developed tumours at 22th-25th day after inoculation (D = 22-25), only 60%-75% of R5-28-inoculated rats were affected by tumours. The frequency and progress of the disease depended on the number of inoculated cells. No metastases were detected in both cases. All affected animals showed large splenomegaly. A possible response of some immune system components to tumours was tested. No tumour-infiltrating lymphocytes were revealed in the tumour tissue. Anti-tumour antibodies were not found in tumour-bearing animal sera. Appropriate changes in peripheral blood lymphocyte subsets were explored. While the relative numbers of both NK cells and Tc were impaired, no changes were noted in numbers of CD4+CD8- T helper cells. Leukocytosis with highly increased numbers of CD11b+ myeloid cells displaying variable expression of CD4 was detected in terminal stages of the disease.

Animals↗
PubMed2004

Phospholipases D1 and D2 coordinately regulate macrophage phagocytosis.

Phagocytosis is a fundamental feature of the innate immune system, required for antimicrobial defense, resolution of inflammation, and tissue remodeling. Furthermore, phagocytosis is coupled to a diverse range of cytotoxic effector mechanisms, including the respiratory burst, secretion of inflammatory mediators and Ag presentation. Phospholipase D (PLD) has been linked to the regulation of phagocytosis and subsequent effector responses, but the identity of the PLD isoform(s) involved and the molecular mechanisms of activation are unknown. We used primary human macrophages and human THP-1 promonocytes to characterize the role of PLD in phagocytosis. Macrophages, THP-1 cells, and other human myelomonocytic cells expressed both PLD1 and PLD2 proteins. Phagocytosis of complement-opsonized zymosan was associated with stimulation of the activity of both PLD1 and PLD2, as demonstrated by a novel immunoprecipitation-in vitro PLD assay. Transfection of dominant-negative PLD1 or PLD2 each inhibited the extent of phagocytosis (by 55-65%), and their combined effects were additive (reduction of 91%). PLD1 and PLD2 exhibited distinct localizations in resting macrophages and those undergoing phagocytosis, and only PLD1 localized to the phagosome membrane. The COS-7 monkey fibroblast cell line, which has been used as a heterologous system for the analysis of receptor-mediated phagocytosis, expressed PLD2 but not PLD1. These data support a model in which macrophage phagocytosis is coordinately regulated by both PLD1 and PLD2, with isoform-specific localization. Human myelomonocytic cell lines accurately model PLD-dependent signal transduction events required for phagocytosis, but the heterologous COS cell system does not.

Animals↗
PubMed2006

[Platelet-derived microparticles stimulate proliferation of granulocyte-macrophage progenitor cells from umbilical cord blood].

This study was aimed to investigate the effect of platelet-derived microparticles (PMP) on stimulating the proliferation of granulocyte-macrophage progenitors (CFU-GM) from umbilical cord blood. Different concentrations of thrombin were adopted to activate the platelets for releasing PMP. Flow cytometry was adopted to evaluate the efficiencies of different concentrations of thrombin to produce PMP. Umbilical cord blood mononuclear cells (MNC) were obtained from healthy donors and the MNC were isolated by Ficoll density gradient centrifugation. MNC were cultured in 2.7% methylcellulose containing different concentration of PMP and colonies were counted under an inverted microscope after 7 days. The result showed that the release rate of PMP activated by 2.0, 1.5, 1.0 and 0.5 U/ml thrombin were 28.7%, 47.7%, 50.1% and 43.9% respectively. The PMP enhanced colony formation in dose-dependent manner. The number of colonies per 2 x 10(5) MNCs in groups of PMP at different concentrations (10, 50 and 100 microg/ml) were 119.8 +/- 32.2,142.8 +/- 45.2 and 180.8 +/- 85.1 respectively. The number of colonies in the groups of PMP at 100 microg/ml and 50 microg/ml were statistically significant when compared with control group (103.0 +/- 24.8) (P < 0.05). The number of colonies per 2 x 10(5) MNC in the group of PMP (10 microg/ml) was 119.8 +/- 32.2 which was higher than that in control group, but there was no statistical significance between two groups. It is concluded that platelet activated with 1.0 U/ml thrombin can get the best release efficiency of PMP and PMP can enhance the proliferation of granulocyte-macrophage progenitor cells of umbilical cord blood.

Blood Platelets↗
PubMed1980

The use of hydroxyurea to study the proliferative state of T-cell precursors (CFUT) in murine bone marrow.

The cycle specific drug, hydroxyurea (HU), has previously been used to study the proliferative kinetics of various hemopoietic precursor cells such as granulocyte-macrophage precursors (CFUc) and multipotential stem cells (CFUs). We have investigated the kinetics of another hemopoietic precursor, a T-cell colony (CFUT). When mice are exposed to two doses of HU, separated by 7 h, CFUT are reduced to approximately 30% of the control value. Surviving cells in the bone marrow quickly replenish the population and return it to normal values 2 days after HU treatment. When fresh bone marrow cells or bone marrow cells harvested from mice exposed 24 h earlier to HU are treated in vitro with HU, CFUT activity is reduced by approximately 70%. These data indicate that CFUT is a rapidly proliferating population with a large proportion of the cells always in cell cycle.

Animals↗
PubMed1986

Expression of lectin receptors on the surface of granulocyte-macrophage progenitor cells (CFU-gm).

It has been emphasized that specific bindings between membrane glycoproteins and membrane lectin-like substances are important in cell-to-cell interactions. We explored the surface of granulocyte-macrophage precursor cells (CFU-gm) by the differential agglutination technique. Enrichment of CFU-gm in the agglutinated fraction, containing the cells which have lectin receptors, from marrow treated with soybean agglutinin (SBA), peanut agglutinin (PNA) and concanavalin A (Con A), suggests the presence of reactive galactosyl and mannosyl residues on the surface of CFU-gm. On the other hand, wheat germ agglutinin (WGA), phytohemagglutinin (PHA) and ulex europaeus agglutinin (UEA), which bind to reactive N-acetylglucosamine, N-acetylgalactosamine and fucose, respectively, did not specifically agglutinate CFU-gm. Thus, reactive groups containing galactosyl and mannosyl structures on the surface of CFU-gm may possibly play a role in the process of cell-to-cell interactions between CFU-gm and marrow stromal cells.

Animals↗
PubMed2003

Dynamics of precursor cell composition in bone marrow culture derived from mice deficient by tumor necrosis factor.

Hemopoiesis in a long-term bone marrow culture derived from mice deficient for tumor necrosis factor was maintained for more than 130 weeks, which was 4 times longer than in cultures from wild type mice. The dynamics of hemopoietic precursor cells of different maturity was studied in the suspension fraction of the culture. The incidence of granulocyt-macrophage precursor cells and cell forming cobblestone areas was studied by the method of limiting dilutions in culture. In contrast to cultures derived from wild type mice, in long-term bone marrow culture derived from tumor necrosis factor deficient mice, first, the incidence of early precursor cells gradually increased and then the incidence of all precursor cells sharply increased.

Animals↗
PubMed2005

Role of Thy 1,2+ cells in the regulation of hemopoiesis during experimental neuroses.

We studied the direct and stromal cell-mediated effects of bone marrow Thy 1,2+ cells on the growth of granulocyte-macrophage and erythroid colonies from the bone marrow of CBA/CaLac mice with experimental neuroses (conflict situation and paradoxical sleep deprivation). Proliferation and differentiation of hemopoietic precursors during neuroses are controlled by regulatory T cells. In conflict situation Thy 1,2+ cells stimulate the growth of hemopoietic precursors, which is associated with their direct effect and interaction with adherent cells of the hemopoiesis-inducing microenvironment. The interaction of Thy 1,2+ cells with adherent bone marrow cells during paradoxical sleep deprivation stimulates the formation of only granulocyte-macrophage colonies.

Animals↗
PubMed2004

IL-7 does not prevent pro-B/pre-B cell maturation to the immature/sIgM(+) stage.

IL-7 plays many fundamental roles during murine B lineage development. One reported function is to maintain progenitors in a developmentally immature state by preventing differentiation to the surface IgM (sIgM)(+) stage. Withdrawal of IL-7 from cultures has been shown to lead to increases in mature traits such as RAG expression, IgL rearrangements and expression of sIgM. These observations have been interpreted as an inductive event promoting the differentiation of progenitor cells. In contrast to this, we reproducibly observe sIgM(+) cells that have differentiated in cultures containing IL-7. We find that sIgM(+) cells arise as a normal consequence when B lineage cells are cultured in the presence of IL-7. However, these cells are short-lived and are quickly replaced by newly emerging sIgM(+) cells that differentiate from sIgM(-) progenitors. Withdrawal of IL-7 from these cultures only prevents the survival and proliferation of CD2(-)sIgM(-) pro-B cells but does not change the number of cells that differentiate to the sIgM(+) stage. This changes the ratio of sIgM(-):sIgM(+) cells and results only in an apparent maturation of the culture as a whole. Therefore withdrawal of IL-7 from these cultures acts as a selection event, not an induction event, for populations that are normally present.

Animals↗
PubMed2004

Differentiation of human umbilical cord blood CD133+ stem cells towards myelo-monocytic lineage.

BACKGROUND: Characterisation of stem cells by flow cytometry, their expansion and differentiation are presently of major interest for cell engineering as the basis of a therapeutic concept for transplantation. Haematopoietic stem cells (HSC) express CD34, the adhesion structure which binds 2L-selectin, CD117, a receptor for stem cell factor (SCF; c-kit ligand), and CD133, a transmembrane protein belonging to the family of mucoproteins. METHODS: The aim of the present investigation was the systematic investigation of proliferation and differentiation characteristics of umbilical cord blood stem cells (UCBSC) isolated by an immmunomagnetic separation system using CD133 antibody-coated microbeads and to evaluate the effects of different sera and various concentrations, as well as the effects of IL-3 and IL-6 on total cell expansion and differentiation of isolated CD133+ cells. Differentiation patterns were measured by flow cytometry. RESULTS: After the immmunomagnetic separation the yield of CD133+ cells was 0.45+/-0.17 x 10(6) cells/ml; the purity of isolated CD133+ cells was 95.79+/-1.86%. The majority of CD133+ cells coexpressed CD117. The most pronounced expansion during cultivation of 2 weeks was achieved in media supplemented with 12.5% horse serum plus 12.5% fetal calf serum (FCS) with stem cell factor and interleukine 3; the fold-expansion was 16.67+/-6.20. During the cultivation period, UCBSC were constantly loosing stem cell markers and differentiated towards myelo-monocyte lineage (granulocytes and/or monocytes). CONCLUSIONS: These in vitro results demonstrate that thorough investigation of various cultivation conditions is needed for successful expansion and differentiation of stem cells towards different lineages to be used therapeutically for replacement of damaged cells.

AC133 Antigen↗
PubMed2006

Derangement of transcription factor profiles during in vitro differentiation of HL60 and NB4 cells.

Sequential up- and down-regulation of a handful of critical transcription factors is required for proper neutrophil differentiation. Malfunction of transcription factors may lead to diseases such as acute myeloid leukemia (AML) and specific granule deficiency. In order to understand the molecular background for normal and malignant granulopoiesis, a good model system is required that faithfully mimics the in vivo transcription factor expression profiles. The two human leukemic cell lines HL60 and NB4 have been widely used as model cell lines for these purposes. Differentiation of HL60 and NB4 cells resulted in asynchronous differentiation to morphologically mature neutrophils over a period of 5-7 days. To obtain cell populations of more even maturity, cells at different stages of in vitro differentiation were purified by immunomagnetic isolation. This resulted in three cell populations that could be classified as promyelocytes, myelocytes/metamyelocytes, and mature neutrophils, respectively. Comparison of transcription factor mRNA profiles from these cell populations with those previously seen in normal human bone marrow, demonstrated that although all of the 14 transcription factors described in vivo, could be detected during in vitro differentiation, vast differences in their expression profiles was observed. These data illustrate the limitations of cell lines as models for normal granulopoiesis.

Cell Differentiation↗