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PubMed1993

Megakaryocyte, erythroid and granulocyte-macrophage colony formation in myelodysplastic syndromes.

Bone marrow progenitor cell assays of three cell lineages, i.e., colony-forming unit megakaryocytes (CFU-Meg), burst-forming unit erythrocytes (BFU-E) and colony-forming unit granulocyte-macrophages (CFU-GM), were performed for 21 patients with myelodysplastic syndromes (MDS). Markedly reduced or absent colony formation was found in 67% of the patients for CFU-Meg and all patients except 2 with refractory anemia (RA) for BFU-E. Abnormal CFU-GM colony formation was found in only 5 of 12 patients with RA and RA with ring sideroblasts, in contrast to all of the RA patients with excess of blasts and excess of blasts in transformation. Defective colony formation of all three cell lineages was seen in 63% of the MDS patients. The colony number of CFU-Meg correlated significantly with the numbers of both BFU-E and CFU-GM. These findings indicate that hematopoiesis in MDS patients is disturbed due to a qualitative or quantitative defect at the multipotent stem cell level.

Adolescent↗

PubMed1995

Azidothymidine and interferon-alpha in vitro effects on hematopoiesis: protective in vitro activity of IL-1 and GM-CSF.

Preclinical and clinical studies with an azidothymidine (AZT)/interferon-alpha (IFN-alpha) combination resulted in a marked and synergistic antiretroviral activity. The administration of the two drugs in HIV-seropositive patients affected with Kaposi's sarcoma, however, induced neutropenia, thrombocytopenia, and, in some cases, anemia. A possible means to improve the therapeutic index of AZT and/or IFN-alpha in AIDS patients could be the addition of hematopoietic growth factors. In vitro activity of cytokines on the hematotoxicity of the AZT-IFN-alpha association has not yet been studied. We have performed an in vitro study to evaluate the toxicity of AZT, IFN-alpha, or both on peripheral blood hematopoietic progenitors (CFU-GM and BFU-E) and to assess the activity of interleukin 1 (IL-1), granulocyte-macrophage colony-stimulating factor (GM-CSF), or both in modifying AZT-IFN-alpha hematotoxicity. Results indicate that AZT, IFN-alpha, and combinations of the two have a dose-dependent inhibitory effect on the in vitro growth of peripheral blood hematopoietic progenitors. Combinations of AZT and IFN-alpha inhibited CFU-GM and BFU-E proliferation in an additive manner. Neither IL-1 nor GM-CSF alone was able to induce a significant reduction of AZT-induced damage. Only the addition to the cultures of both cytokines partially curbed the antiproliferative activity of AZT at low dosages.

Antimetabolites↗

PubMed1993

Gender and response to antilymphocyte globulin (ALG) for severe aplastic anaemia.

We have evaluated the speed of haematological recovery in 103 severe aplastic anaemia (SAA) patients treated with antilymphocyte globulin (ALG) and followed at our institution for 3-15 years. We found that haemopoietic recovery was significantly delayed in six girls under the age of 10 years. This slow recovery in girls might be explained by their relative inability to release haemopoietic growth factors, granulocyte colony stimulating activity and burst promoting activity, compared to all other sex and age groups. This defect is not explained by disease severity at presentation and thus indicates a functional abnormality of monocytes/macrophages and T-lymphocytes in addition to the deficiency of haemopoietic stem cells. In a multivariate analysis, low factor production and low pretreatment reticulocyte counts turned out to be strong predictors of slow haemopoietic recovery. We conclude that young girls have a particular form of SAA characterized by low haemopoietic factor production and delayed recovery after ALG. They are preferential candidates for early bone marrow transplantation or, if they are not eligible, for treatment with recombinant human haemopoietic growth factors.

Adolescent↗

PubMed1994

Recombinant human interleukin-4 inhibits the production of granulocyte-macrophage colony stimulating factor by blood mononuclear cells.

The effect of recombinant human (rh) interleukin-4 (rIL-4) on human blood BFU-E was investigated using two populations of cells: platelet-depleted low-density mononuclear cells (FH,Pl- cells), as unpurified cells, and highly purified BFU-E. When FH,Pl- cells were cultured with rh-erythropoietin (rEp), rIL-4 inhibited BFU-E growth in a dose-dependent manner. However, the addition of rIL-4 did not affect rh-interleukin-3 (rIL-3) supported BFU-E growth. Limiting dilution analysis (LDA) of FH,Pl- cells showed that rIL-4 suppressed endogenous production of burst-promoting activity (BPA) by accessory cells. Highly purified BFU-E were used as target cells to measure BPA in the conditioned medium (CM) that was prepared by FH,Pl- cells. When 100 purified BFU-E were cultured in 0.5 ml clots with 20% (vol/vol) of the CM, the number of BFU-E colonies was increased by the CM. The increase was significantly reduced by the addition of the CM prepared in the presence of rIL-4, but anti-IL-4 blocked the effect of rIL-4. The concentration of IL-3 and granulocyte-macrophage colony-stimulating factor (GM-CSF) in CM was determined by an enzyme-linked immunoadsorbent assay (ELISA). The spontaneous production of GM-CSF but not IL-3 was detected, and this was significantly decreased in the presence of rIL-4. Anti-GM-CSF but not anti-IL-3 inhibited CM supported BFU-E growth, indicating that the main BPA in the CM is GM-CSF and that rIL-4 suppresses the spontaneous production of GM-CSF by accessory cells. From these studies, we conclude that rIL-4 has a unique mechanism as a negative regulator on erythropoiesis through the inhibition of BPA production by blood mononuclear accessory cells.

Adult↗

PubMed2001

Comparison of megakaryopoiesis in vitro of paired peripheral blood progenitor cells and bone marrow harvested during remission in patients with acute myeloid leukaemia.

We have studied paired peripheral blood progenitor cells (PBPC) and bone marrow (BM) samples from 12 acute myeloid leukaemia (AML) patients following intensive chemotherapy, and assessed direct granulocyte-macrophage colony-forming units (CFU-GM), erythroid burst-forming units (BFU-E), megakaryocyte CFU (CFU-Mk) numbers and the production of CD61+ (platelet glycoprotein IIIa) cells in suspension culture in response to various haemopoietic growth factor combinations. We found that CFU-GM and BFU-E numbers per 105 mononuclear cells were similar in both AML PBPC and BM harvests; CFU-Mk numbers, however, were significantly higher in PBPC than BM. In addition, the higher total white cell count of the PBPC harvests meant that PBPC have much higher numbers of total progenitors per collection. CD61+ cell numbers in suspension cultures of AML PBPC and BM were lower than those of harvested normal marrow. However, response to pegylated recombinant human megakaryocyte growth and development factor (PEGrHuMGDF) both alone and in combination with other growth factors was qualitatively similar to that of normal BM. As with normal BM, response to PEGrHuMGDF alone did not increase further with addition of granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage CSF (GM-CSF), interleukin 6 (IL-6) or erythropoietin (EPO) in the AML PBPC and BM. Further responses over PEGrHuMGDF alone were seen when added with stem cell factor (SCF) or with a combination of SCF + IL-3 + EPO in both AML PBPC and BM cultures; however, the magnitude of the response was greater in the PBPC cultures. Response to PEGrHuMGDF + IL-3 was seen in the PBPC cultures but not in the AML BM. These data suggest that, in AML patients, there are proportionally more megakaryocyte progenitor cells in the mobilized PBPC than in the BM harvests, which would explain the more rapid platelet recovery following PBPC autografts.

Acute Disease↗

PubMed1996

Thrombopoietin expands erythroid, granulocyte-macrophage, and megakaryocytic progenitor cells in normal and myelosuppressed mice.

Thrombopoietin (Tpo), the ligand for the proto-oncogene receptor c-Mpl, increases megakaryocyte size, ploidy, and surface expression of platelet-specific glycoproteins, is inversely related to platelet mass, and is a potent in vivo stimulus of platelet production. However, several features of c-mpl biology, and that of its viral counterpart v-mpl, suggest that the action of Tpo may not be strictly limited to megakaryocytopoiesis. To investigate the possibility that Tpo might affect a multitude of cell lineages, we studied the effects of in vivo administration of the hormone on multiple types of marrow and splenic clonogenic hematopoietic progenitors. We report that Tpo acts to expand BFU-E, CFU-GM, and CFU-Mk and redistribute CFU-E in normal mice and to hasten the recovery of all of these progenitor cell types in myelosuppressed animals. These findings argue that the hematopoietic progenitor cell compartment responds to Tpo as a whole and that the in vivo effects of Tpo administration may be more wide-ranging than previously anticipated.

Animals↗

PubMed1990

Radioprotection of mice with interleukin-1: relationship to the number of erythroid and granulocyte-macrophage colony-forming cells.

This report presents the results of an investigation of changes in the number of erythroid and granulocyte-macrophage colony-forming cells (GM-CFC) that had occurred in tissues of normal B6D2F1 mice 20 h after administration of a radioprotective dose (150 ng) of human recombinant interleukin-1 (rIL-1). Neutrophilia in the peripheral blood and changes in the tissue distribution of GM-CFC demonstrated that cells were mobilized from the bone marrow in response to rIL-1 injection. For example, 20 h after rIL-1 injection marrow GM-CFC numbers were 80% of the numbers in bone marrow from saline-injected mice. Associated with this decrease there was a twofold increase in the number of peripheral blood and splenic GM-CFC. Also, as determined by hydroxyurea injection, there was an increase in the number of GM-CFC in S phase of the cell cycle in the spleen, but not in the bone marrow. Data in this report suggest that when compared to the spleen, stimulation of granulopoiesis after rIL-1 injection is delayed in the bone marrow. Also, the earlier recovery of GM-CFC in the bone marrow of irradiated mice is not dependent upon an increase in the number of GM-CFC at the time of irradiation.

Animals↗

PubMed1993

Effects of total-body irradiation on bone marrow erythroid burst-forming units (BFU-E) and hemopoietic regeneration in dogs.

The acute and long-term effects of total-body X irradiation (TBI) on early erythroid progenitors, burst-forming units (BFU-E), in the bone marrow of beagles were studied for midline tissue doses of 1.6 and 2.4 Gy. After both radiation doses the initial reduction in the concentration of BFU-E was greater than that found for the granulocyte-macrophage progenitor cells (GM-CFC) and thus was in general agreement with the higher in vitro radiosensitivity of BFU-E compared to GM-CFC. After TBI with 1.6 Gy the GM-CFC and BFU-E returned to their normal levels within 2-4 weeks without showing long-term radiation effects. In contrast, after TBI with 2.4 Gy the concentrations of GM-CFC and BFU-E remained below the pretreatment levels up to 1 year after exposure. For a given midline tissue dose, the extent of the long-term effect of radiation on the BFU-E in a certain bone marrow site seems to be dependent on the local radiation dose in the respective bone marrow space. The minor radiation effects observed in the erythrocyte concentration in the peripheral blood, the hematocrit, and the hemoglobin concentration point to the enormous compensatory capacity of the more mature erythropoietic transit population to increase the proliferative capacity upon demand.

Animals↗

PubMed1993

Sensitivity of committed hematopoietic progenitor cells in vitro (BFU-E, CFU-E, CFU-GM) and two human carcinoma cell lines toward rhodamine-123 and phosphonium salt II-41.

Lipophilic cationic compounds accumulate more rapidly in the mitochondria of many carcinoma-derived cells than in non-transformed cells, thus leading to their pronounced cytotoxic effects on carcinoma cells. In this report, in order to measure tumoricidal effects vs cytotoxicity to normal hematopoietic progenitors, we studied the sensitivity of committed human hematopoietic cells in vitro and two human carcinoma cell lines (2008 ovary carcinoma cells and HT29 colon cells) toward two such compounds, rhodamine-123 and phosphonium salt II-41. Continuous exposure of human marrow cells to rhodamine-123 or phosphonium salt II-41 for 7 and 14 days produced dose-related inhibition of colony formation of erythroid burst-forming units (BFU-E), erythroid colony forming units (CFU-E), and CFU-granulocyte/macrophage (CFU-GM). The average values of IC50 for several different human bone marrows are approximately 0.9-1.1 microM for rhodamine-123 toward BFU-E, CFU-E and CFU-GM, and 31-38 microM for phosphonium salt II-41 toward the same hematopoietic progenitors. These IC50 values are similar for each type of hematopoietic progenitors. In each case, rhodamine-123 appears to be at least 30-fold more growth suppressive than phosphonium salt II-41 in these in vitro colony assays. In addition, the sensitivity of these hematopoietic progenitors toward these two compounds is comparable to the inhibition of colony formation for the two human carcinoma cell lines. The lack of differences in the sensitivity among the various hematopoietic progenitors in vitro may disagree with previous studies showing there are vast differences in the state of cell cycle for these hematopoietic progenitor cells. However, these observations about the cytotoxicity in vitro can be explained by assuming that the cytotoxicity of these compounds depends on other factors such as differentiation processes, which result in the appearance of many or very active mitochondria. Alternatively, the lack of differences in the sensitivity of the in vitro colony formation can also be attributed to a reported decrease in expression of P-glycoprotein, a multidrug efflux pump, in the differentiating hematopoietic progeny cells.

Colonic Neoplasms↗

PubMed1991

Impaired in vitro growth of peripheral blood hematopoietic progenitor cells in HIV-infected patients: evidence of an inhibitory effect of autologous T lymphocytes.

The in vitro growth of both circulating granulocyte-macrophage (CFU-GM) and erythroid (BFU-E) progenitor cells was assessed in 29 individuals infected with the human immunodeficiency virus (HIV) at different stages of infection. The effects of autologous T lymphocytes, adherent cells, and serum on the in vitro growth of hematopoietic progenitor cells were also investigated. Compared with normal controls, baseline growth was significantly reduced for both CFU-GM and BFU-E in HIV-infected patients, independent of the clinical stage of the disease. In HIV-infected subjects depletion of autologous T cells was associated with a significant increase of progenitor cell growth. Similar results were observed after selective depletion of CD8+ T cells, while readdition of T cells to T-depleted mononuclear cells reduced the number of CFU-GM. A dose-dependent colony inhibitory activity was found in conditioned medium of T cells from HIV-infected subjects. Neither autologous adherent cells nor serum from either HIV+ or HIV- subjects had any significant effect on the in vitro growth of CFU-GM. These results indicate that the in vitro growth of circulating hematopoietic progenitor cells is impaired even in the early stages of HIV infection, and that autologous T cells exert an inhibitory effect on the in vitro growth of progenitor cells, possibly via soluble mediator(s).

Acquired Immunodeficiency Syndrome↗

PubMed2002

Epstein-Barr virus inhibits the development of dendritic cells by promoting apoptosis of their monocyte precursors in the presence of granulocyte macrophage-colony-stimulating factor and interleukin-4.

Epstein-Barr virus (EBV) is a tumorigenic human herpesvirus that persists for life in healthy immunocompetent carriers. The viral strategies that prevent its clearance and allow reactivation in the face of persistent immunity are not well understood. Here we demonstrate that EBV infection of monocytes inhibits their development into dendritic cells (DCs), leading to an abnormal cellular response to granulocyte macrophage-colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4) and to apoptotic death. This proapoptotic activity was not affected by UV inactivation and was neutralized by EBV antibody-positive human sera, indicating that binding of the virus to monocytes is sufficient to alter their response to the cytokines. Experiments with the relevant blocking antibodies or with mutated EBV strains lacking either the EBV envelope glycoprotein gp42 or gp85 demonstrated that interaction of the trimolecular gp25-gp42-gp85 complex with the monocyte membrane is required for the effect. Our data provide the first evidence that EBV can prevent the development of DCs through a mechanism that appears to bypass the requirement for viral gene expression, and they suggest a new strategy for interference with the function of DCs during the initiation and maintenance of virus-specific immune responses.

Apoptosis↗

PubMed1992

Prevalence of the primitive megakaryocyte progenitors (BFU-meg) in adult human peripheral blood.

The in vitro growth of early (megakaryocyte burst-forming units, BFU-meg) and late (megakaryocyte colony-forming units, CFU-meg) megakaryocyte (meg) progenitors has been evaluated in normal adult human peripheral blood (PB). All the experiments were carried out using CD34+ cells, which were assayed in a serum-free fibrinclot assay. PB BFU-meg were morphologically characterized as plurifocal aggregates containing greater than 50 cells/colony, distinct from unifocal CFU-meg, in a limiting dilution assay. At variance with PB CFU-meg, PB BFU-meg were unaffected by the complement-mediated cytotoxicity with anti-HLA-DR. The optimal source of colony-stimulating activity for PB BFU-meg growth was recombinant human interleukin 3 (rhIL-3; 100 U/ml), which supported a significantly higher number of BFU-meg in comparison with recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF; 200 U/ml, p = 0.043). Combinations of rhIL-3 (100 U/ml) plus rhGM-CSF (200 U/ml), rhIL-3 plus recombinant human interleukin 6 (rhIL-6; 100 U plus 100 U/ml) or rhIL-3 plus rhGM-CSF plus rhIL-6 (100 U plus 200 U/ml plus 100 U/ml) failed to further increase the number of PB BFU-meg with respect to rhIL-3 (100 U/ml) alone. Both PB BFU-meg and CFU-meg were markedly inhibited, in a dose-dependent fashion, by increasing doses of human purified transforming growth factor-beta 1 (TGF-beta 1) (from 0.001 to 10 ng/ml). Finally, the CFU-meg/BFU-meg ratio in PB (0.52) was significantly different from that of normal bone marrow (2.3), clearly indicating that adult human peripheral blood predominantly carries primitive megakaryocytic progenitors.

Adult↗

PubMed1994

Sequential changes in stem cell markers in peripheral blood and leukapheresis samples after injections of recombinant human granulocyte colony-stimulating factor in patients with urogenital malignant solid tumors: a preliminary study.

In order to evaluate the mobilization effect of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on peripheral blood stem cells (PBSCs), rhG-CSF was given to patients with urogenital malignancy before chemotherapy. Markers for the stem cells, such as colony forming unit-granulocyte/macrophage (CFU-GM) and burst forming unit-erythrocyte (BFU-E), were sequentially monitored in peripheral blood and leukapheresis samples. Five patients, including a 13-year-old boy, were given 5 micrograms/kg rhG-CSF subcutaneously: the pediatric case for four consecutive days and the adult cases for six consecutive days (53-72 years of age). None of the patients had received chemotherapy within the four weeks prior to the start of the rhG-CSF series. PBSC collections were performed on the fifth day in the pediatric case and on the fifth and seventh days in the adult cases. Progenitor cells were monitored by methyl-cellulose cell culture techniques. CFU-GM on day 5 of the rhG-CSF series in peripheral blood increased 14- to 53-fold compared with samples taken immediately before the series. CFU-GM in the leukapheresis products on day 5 was greatest (70 x 10(3)/kg) in the pediatric case and least (14 x 10(3)/kg) in the oldest patient's case. The totals of the CFU-GM collected by two phereses in the adult cases were 21-73 x 10(3)/kg and the totals of CD34 positive cells were 0.6 to 1.4 x 10(6)/kg. The data suggest rhG-CSF to induce sufficient PBSCs for bone marrow rescue into the peripheral blood without any preceding chemotherapy. The patient's age may, however, be a contributory factor in using this method.

Adolescent↗

PubMed1996

Expression of Fas/CD95 and Bcl-2 by primitive hematopoietic progenitors freshly isolated from human fetal liver.

The cell-surface expression and the functional status of the CD95/Fas antigen on primitive hematopoietic progenitors (PHPs) freshly isolated from human fetal liver (FL) were studied. PHPs were phenotypically defined as CD34++ CD38 -/+ cells. The most immature subfractions of PHPs, CD34++CD38- and CD34+2CD38+ FL cells, expressed CD95, whereas the more mature CD34++CD38++ and CD34+CD38++2 FL cells displayed low CD95 expression. Combinations of cytokines, such as kit ligand (KL) + interleukin-3 or KL + granulocyte-macrophage colony-stimulating factor (GM-CSF) upregulated the expression of CD95 on PHPs upon in vitro culture. Tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) further increased the CD95 expression induced by KL+GM-CSF. The hematopoietic potential of sorted CD34++lineage (lin)- CD95+ versus CD34++ lin-CD95-FL cells was compared by colony-forming unit-culture (CFU-C) assays performed in serum-deprived medium. Lin+ cells were composed of erythrocytes, monocytes, T cells, B cells, and natural killer cells. Our results indicated that both CD95- and CD95+ subsets contained pluripotent progenitors, generating myeloid and erythroid progenitors. The functional status of CD95 and the effects of TNF-alpha and IFN-gamma, cytokines known to induce CD95-mediated apoptosis, were analyzed by incubation of PHPs in the presence of anti-CD95 monoclonal antibodies (MoAbs). The effect of anti-CD95 MoAbs was measured by viable cell counting, flow cytometry, and CFU-C assays. A decrease of CFU-C numbers was observed in the presence of anti-CD95 MoAbs and TNF-alpha and/or IFN-gamma. However, whereas growth factor deprivation induced apoptosis of PHPs, cross-linking of CD95 did not lead to apoptosis of PHPs measured by flow cytometry and viable cell counting. The correlation of increased intracytoplasmic levels of bcl-2 with high levels of cell-surface CD34 and the presence of CD95 on fresh FL cells suggests that bcl-2 may be involved in protecting against CD95-mediated apoptosis of FL PHPs.

Antibodies, Monoclonal↗

PubMed1990

Interleukin-1 alpha also induces granulocyte-macrophage colony-stimulating factor in immature normal bone marrow cells.

The cytokine interleukin-1 (IL-1) plays a role in the regulation of normal as well as leukemic hematopoiesis. In acute myeloid leukemia (AML), IL-1 induces autocrine granulocyte/macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor (TNF) production, and these factors may then synergistically induce proliferation in AML blast cells. In this report, we show that IL-1 stimulates DNA synthesis of highly enriched normal bone marrow blast cells (CD34 positive, adherent cell depleted, CD3/CD14/CD15 negative). The stimulative effect of IL-1 can be blocked with neutralizing anti-TNF alpha and anti-GM-CSF antibodies and, most efficiently, by the combination of anti-TNF alpha and anti-GM-CSF, but not with anti-G-CSF antibody, suggesting that IL-1-induced proliferation was initiated through TNF and GM-CSF release. Concentrations of TNF and GM-CSF increased in the culture medium of normal bone marrow blast cells after IL-1 induction. Of the IL-1-induced cells, 12% were positive for GM-CSF mRNA by in situ hybridization, as opposed to 6% of non-induced cells. Thus, in addition to its effect on leukemic blast cells, IL-1 also acts on normal marrow blast cells. We propose a scheme where IL-1 stimulation of normal bone marrow blast cells leads to the induction of TNF alpha and GM-CSF, which in association stimulate DNA synthesis efficiently according to a paracrine or autocrine mechanism within the marrow blast cell compartment.

Adult↗

PubMed1995

Juvenile chronic myelogenous leukemia: in vitro characterization before and after allogeneic bone marrow transplantation.

In previously published studies on patients with juvenile chronic myelogenous leukemia (JCML), excessive proliferation of malignant monocyte-macrophage elements and impaired growth of normal hematopoietic progenitors were demonstrated. A selective hypersentivity of granulocyte-macrophage progenitors (CFU-GM) to granulocyte-macrophage colony stimulating factor (GM-CSF) seems to represent the main pathogenetic mechanism. Allogeneic bone marrow transplantation (BMT) has been demonstrated to be the only curative strategy for patients with JCML. In this study, we evaluated the growth of peripheral blood hematopoietic progenitors in semisolid cultures in two children with JCML before and after allogeneic BMT. Serum levels of GM-CSF, interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-alpha) were also assessed. IL-1-beta, GM-CSF and TNF-alpha serum levels of the patients before and after BMT did not differ significantly from those obtained in 45 healthy controls. After marrow transplant, the engraftment of donor hematopoietic stem cell was associated with the disappearance of both pretransplant GM-CSF hypersensitivity and CFU-GM spontaneous growth. The inhibitory effect on the growth of normal hematopoietic progenitors also resolved. This confirms that the substitution of the pathological hematopoietic progenitors represents the basis for the curvative effect of allogeneic BMT in the treatment of JCML, abolishing both the excessive responsiveness of JCML progenitor cells even to very low concentrations of GM-CSF and the growth-inhibitory effect on normal hematopoiesis.

Bone Marrow Transplantation↗

PubMed1991

In vitro differentiation and proliferation of human hematopoietic progenitors: the effects of interleukins 1 and 6 are indirectly mediated by production of granulocyte-macrophage colony-stimulating factor and interleukin 3.

The effect of recombinant human interleukin (IL)-1 and IL-6 on the differentiation and proliferation in vitro of human granulocyte-macrophage (GM) and erythroid progenitors has been investigated in either fetal bovine serum (FBS)-supplemented or FBS-deprived cultures. Sources of progenitor cells were unfractionated bone marrow cells or marrow cells depleted of adherent and/or T cells. Each interleukin was investigated either alone or in combination with GM-colony-stimulating factor (CSF), IL-3 and erythropoietin (Epo), or granulocyte (G)-CSF. In FBS-supplemented cultures of unfractionated marrow cells, IL-1 induced optimal GM colony growth and increased by 50% the number of erythroid bursts that formed in the presence of Epo. The addition to these cultures of a neutralizing anti-GM-CSF monoclonal antibody or of an anti-IL-3 serum decreased the growth of GM colonies by 80% and 40%, respectively. Under the same conditions, IL-6 had no effect on GM colony growth but increased by 90% the number of erythroid bursts. This effect was partially (40%) neutralized by addition of anti-IL-3 serum. IL-1 and IL-6 were weak stimuli, or had no effect at all, either alone or in combination with GM-CSF and IL-3 in FBS-deprived cultures or in FBS-supplemented cultures of nonadherent or nonadherent, T-cell-depleted marrow cells. IL-1 and IL-6 had no effect, either alone or in combination with IL-3, in maintaining the number of progenitor cells in short-term liquid suspension cultures. These results indicate that the actions of IL-1 and IL-6 on hematopoiesis are mainly indirect and mediated by the production of GM-CSF and/or IL-3 by accessory cells. However, neither IL-1 nor IL-6 alone is sufficient to stimulate production of growth factor(s) by accessory cells, and at least a second stimulus, provided by FBS, is also required. These data are in agreement with a multisignal model of regulation of the expression of growth factor genes.

Antibodies↗

PubMed2006

Recombinant human granulocyte-colony-stimulating factor-mobilized and apheresis-collected endothelial progenitor cells: a novel blood cell component for therapeutic vasculogenesis.

BACKGROUND: Endothelial progenitor cells (EPCs) have been identified among hematopoietic tissue-derived progenitor cells that are mobilized into the peripheral blood (PB) as a result of tissue injury. It therefore seems likely that circulating EPCs have therapeutic potential by aiding in the neovascularization of ischemic tissue. This study provides clinical data on the availability of circulating EPCs at steady state and after recombinant human granulocyte-colony-stimulating factor (rHuG-CSF) mobilization and their collection by leukapheresis. STUDY DESIGN AND METHODS: Eight healthy donors underwent rHuG-CSF treatment over 4 days, followed by leukapheresis. Blood samples taken before rHuG-CSF treatment and before apheresis as well as apheresis-collected samples were analyzed by flow cytometry and by real time reverse transcription-polymerase chain reaction for cells expressing EPC-specific surface markers and tissue markers, respectively, and for EPC colony-forming cells. RESULTS: The median PB concentration of CD34+133+ vascular endothelial growth factor receptor-2 (VEGFR-2)-+ EPCs increased 8-fold from steady state to mobilized, and the concentration of CD34+133-VEGFR-2+ EPCs increased by 10-fold. This mobilization pattern was similar to that of hematopoietic CD34+, CD133+, and CD34+117+ progenitor cells. The increase in the median circulating colony-forming unit EPC concentration was 10-fold over baseline. The median absolute number of CD34+133+VEGFR-2+ cells collected by large-volume leukapheresis was 0.8 x 10(6) per kg of body weight. In addition, a small subset of immature CD133+34- cells coexpressing VEGFR-2 was identified in mobilized PB and in the apheresis collection. EPC-specific cells contained in the apheresis product were also identified as expressing mRNA for the CD31 antigen, Tie-2, and VEGFR-2. CONCLUSION: Circulating EPCs represent a novel blood cell component that can be collected by apheresis in large quantities and can be used clinically, either unmanipulated or EPC-selected, for therapeutic vasculogenesis.

Adult↗