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Biomedical subjects

H E Broxmeyer

Publications and source records attributed to H E Broxmeyer.

At least 289 records · Page 16Linked to original sources
PubMed1989

In vivo biologic activities of recombinant human granulocyte-macrophage colony-stimulating factor.

We evaluated the biologic effects of recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) in 25 patients with malignancy and/or bone marrow failure of diverse etiologies. The continuous infusion of GM-CSF (15 to 500 micrograms/m2/day) elicited marked leukocytosis (2- to 70-fold increase), consisting primarily of neutrophils, eosinophils, and monocytes. Six patients with cytopenias experienced a multilineage response characterized by significant increases in platelet counts and improvement in erythropoiesis. Response in blood counts was accompanied by significant increases in bone marrow cellularity, myeloid:erythroid cell ratios, and frequency of cycling progenitors, indicating an effect at the stem cell level. By premature chromosome condensation analysis, neutrophils from patients with myeloid diseases were found to be derived from normal as well as abnormal clones. Side effects were generally mild and commonly included constitutional symptoms and bone pain. These results indicate that GM-CSF is a significant stimulus for hematopoiesis in vivo and might play an important role in several clinical arenas.

Adult↗
PubMed1989

Suppressive biological activity of a synthetic pentapeptide on highly enriched human and murine marrow hematopoietic progenitors: synergism with recombinant human tumor necrosis factor-alpha and interferon-gamma.

The synthetic pentapeptide pGlu-Glu-Asp-Cys-Lys (SPI) was evaluated in vitro alone and in combination with recombinant human tumor necrosis factor-alpha (TNF-alpha) and/or interferon-gamma (IFN-gamma) for effects on colony formation by hematopoietic progenitor cells (HPC) present in low-density (LD), nonadherent low-density T-lymphocyte-depleted (NALT-), and highly enriched sorted progenitor cells from normal human bone marrow. Progenitor cells in NALT- fractions were further enriched by cell sorting using two-color fluorescence on a Coulter Epics 753 flow cytometry apparatus with My10 and HLA-DR monoclonal antibodies. The sorted My10 DR+ progenitor cell population had a cloning efficiency of up to 38% for granulocyte-macrophage colony-forming units (CFU-GM), erythroid burst-forming units (BFU-E), and multipotential colony-forming units (CFU-GEMM). SP1 inhibited, by up to 86%, each of the colony-forming cells in a dose-dependent fashion. The sensitivities of the different progenitor cells to inhibition by the pentapeptide were the same when My10 DR+ marrow cells were used, and the progenitor cells in the My10 DR+ fraction were more sensitive than the cells in the LD or NALT- fraction to inhibition by SP1. The suppressive activity of SP1 on purified HPC was confirmed when 10(-3) M SP1 completely inhibited colony and cluster formation from a population of mouse bone marrow cells in which one of two cells was a CFU-GM. The effects of SP1 were not absolutely cell-cycle-specific for human HPC, but the non-S-phase cells were less sensitive than the S-phase cells to the suppressive effects of SP1. SP1 synergized with TNF-alpha and/or IFN-gamma to inhibit proliferation of progenitor cells using both LD or My10 DR+ human marrow cells stimulated by recombinant human interleukin 3 (IL-3). These studies suggest that the suppressive effect of SP1 occurs in the absence of certain accessory cells (e.g., monocytes and T-lymphocytes), that this effect may be mediated directly at the level of the HPC, and that this pentapeptide can be considered a candidate modulatory molecule for HPC proliferation.

Animals↗
PubMed1989

Cell cycle status of erythroid (BFU-E) progenitor cells from the bone marrows of patients on a clinical trial with purified recombinant human granulocyte-macrophage colony-stimulating factor.

Human Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) is active in vitro as a Burst Promoting Activity (BPA) for human erythroid (BFU-E) progenitor cells. In order to evaluate the effectiveness of GM-CSF as a proliferation-inducing stimulus for BFU-E in vivo, bone marrow cells from patients on a phase I/II clinical trial with recombinant human (rh) GM-CSF, were assessed in vitro for effects on the cycling status of BFU-E. Prior to treatment, BFU-E from marrows of the majority of these patients were in a slowly cycling state. Administration of rhGM-CSF to the patients enhanced BFU-E proliferation, and cessation of treatment with rhGM-CSF resulted in BFU-E returning to a slowly cycling state. Similar results were noted for CFU-GM. This study demonstrates that rhGM-CSF has proliferation-inducing activity for BFU-E in vivo, substantiating the in vitro BPA activity previously noted for GM-CSF, although it is not possible from the present studies in vivo to determine if this effect on BFU-E is directly or indirectly mediated.

Bone Marrow↗
PubMed1989

Stimulation of nonclonal hematopoiesis and suppression of the neoplastic clone after treatment with recombinant human granulocyte-macrophage colony-stimulating factor in a patient with therapy-related myelodysplastic syndrome.

A complete hematologic remission was achieved in a patient with therapy-related preleukemia and transfusion-dependent pancytopenia after treatment with recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF). The patient remained in remission for nearly 1 year despite the discontinuation of GM-CSF treatment. Several lines of evidence suggest that normal hematopoiesis was restored after GM-CSF treatment. First, the cytogenetic anomaly, which was present before GM-CSF, completely disappeared after three cycles of treatment. Cytogenetic conversion was documented by conventional karyotypic evaluation of mitotic bone marrow cell preparations as well as by premature chromosome condensation analysis of the nonmitotic cells of bone marrow and peripheral blood. Second, the growth pattern and cycle status of bone marrow granulocyte-macrophage (CFU-GM) and erythroid (BFU-E) progenitor cells were found to be normal during remission. Third, X chromosome-linked restriction fragment length polymorphism-methylation analysis of DNA from mononuclear cells (greater than 80% lymphocytes) and mature myeloid elements showed a polyclonal pattern. These findings suggest that restoration of hematopoiesis in this patient after GM-CSF treatment may have resulted from suppression of the abnormal clone and a selective growth advantage of normal elements.

Adenocarcinoma↗
PubMed1989

Lactoferrin decreases monocyte-induced fibroblast production of myeloid colony-stimulating activity by suppressing monocyte release of interleukin-1.

Lactoferrin (Lf) is a negative regulator of myelopoiesis which operates by suppressing the release from mononuclear phagocytes of GM colony-stimulating factor (GM-CSF) or monokines which can then induce the release of GM-CSA from accessory cells. In this study, endotoxin-depleted, purified iron-saturated human Lf was assessed for its effect on the production of interleukin-1 by cultured monocytes and their subsequent effect on colony-stimulating factor release from cultured fibroblasts. Monocytes were grown with or without Lf and Lf that had previously been incubated with monoclonal anti-Lf. The monocyte-conditioned medium was then either assayed for the presence of interleukin-1 (IL-1) with an enzyme-linked immunosorbent assay or for its ability to stimulate fibroblasts to release growth factors for CFU-GM, BFU-E, or CFU-Mix colonies. In the presence of Lf (10(-7) or 10(-8) mol/L), GM colony-stimulating activity (GM-CSA) was suppressed by 31% to 73%, whereas stimulating activities for BFU-E and CFU-mix colony formation were suppressed by 93% to 100%. Antibody to Lf completely abrogated the suppressive effects observed with Lf, whereas antibody to IL-1 ablated the induction by monocyte-conditioned medium of CSA release by fibroblasts. Lf at 10(-7) and 10(-8) mol/L also reduced IL-1 synthesis by cultured monocytes from 60% to 77%. The inhibitory effects of Lf were only observed when Lf was added before adherence of the monocytes for culture. If Lf was added at the time of adherence or after adherence, no suppression was observed. We conclude that the inhibition of GM-CSA production/release by Lf is mediated through inhibition of the synthesis/release of IL-1 by mononuclear phagocytes. This inhibition of IL-1 prevents accessory cells from producing and/or releasing GM-CSA.

Bone Marrow Cells↗
PubMed1989

Suppressive effects in vivo of purified recombinant human H-subunit (acidic) ferritin on murine myelopoiesis.

Purified recombinant human heavy-chain (acidic) ferritin (rHF) was assessed in vivo in mice for effects on the proliferation (percentage of cells in S-phase) and absolute numbers of granulocyte-macrophage (CFU-GM), erythroid (BFU-E), and multipotential (CFU-GEMM) progenitor cells in the femur and spleen and on the nucleated cells in the marrow, spleen, and blood. rHF significantly decreased cycling rates and absolute numbers of marrow and splenic hematopoietic progenitors and marrow and blood nucleated cellularity. These effects were apparent in BDF1, C3H/Hej and DBA/2 mice and were dose dependent, time related, and reversible. Suppressive effects were noted within three hours for progenitor cell cycling, within 24 hours for progenitor cell numbers, and within 48 hours for circulating neutrophils. Additionally, hematopoietic progenitor cells in DBA/2 mice infected with the polycythemia-inducing strain of the Friend virus complex (FVC-P) were insensitive to the in vivo administration of rHF. These studies demonstrate activity of rHF in vivo on myelopoiesis of normal but not FVC-P-infected mice. Since rHF suppresses hematopoietic progenitor cell proliferation from normal donors in vitro and from normal mice in vitro and in vivo but does not suppress progenitor cells from patients with leukemia in vitro or from mice with FVC-P-infection in vitro or in vivo, rHF may be useful as a candidate adjunct molecule for the protection of normal hematopoietic progenitor cells during chemotherapy.

Animals↗
PubMed1988

Stimulation of myelopoiesis in patients with aplastic anemia by recombinant human granulocyte-macrophage colony-stimulating factor.

Aplastic anemia is a syndrome in which pancytopenia occurs in the presence of hypocellularity of the bone marrow. To assess the biologic activities of recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) in aplastic anemia, we gave GM-CSF (60 to 500 micrograms per square meter of body-surface area) to 10 patients with moderate or severe disease, by continuous intravenous infusion daily for two weeks, and repeated the treatment after a two-week rest period. The treatment increased the white-cell count (1.6- to 10-fold) in all patients, primarily because of an increase in the numbers of neutrophils (1.5 to 20-fold), eosinophils (12- to greater than 70-fold), and monocytes (2- to 32-fold). Rates of hydrogen peroxide production in purified granulocyte fractions increased during GM-CSF treatment. Increases in bone marrow cellularity, myeloid precursor cells, and myeloid:erythroid cell ratios accompanied the white-cell response. Despite the in vivo response of the white-cells, the concentration of colony-forming cells remained the same. Measurable concentrations of interleukin-2 (2 to 15 units per milliliter) were found in the serum of 8 patients, and high levels of erythropoietin (81 to 1200 IU per liter) were found in 10 patients. The predominant side effects were constitutional symptoms. These results indicate that recombinant human GM-CSF is effective in stimulating myelopoiesis in patients with severe aplastic anemia and may benefit some patients in whom the disorder is refractory to standard forms of therapy.

Adolescent↗
PubMed1988

Synergistic effects of purified recombinant human and murine B cell growth factor-1/IL-4 on colony formation in vitro by hematopoietic progenitor cells. Multiple actions.

Purified recombinant human B cell growth factor-1/IL-4 was evaluated, alone and in combination, with purified preparations of recombinant human (rhu) CSF or erythropoietin (Epo) for effects on colony formation by human bone marrow CFU-GM progenitor cells (GM) and burst forming unit-E progenitor cells. rhu IL-4 synergized with rhu G-CSF to enhance granulocyte colony formation, but had no effect on CFU-GM colony formation stimulated by rhu GM-CSF, rhu IL-3, or rhu CSF-1. Rhu IL-4 synergized with Epo to enhance BFU-E colony formation equal to that of Epo plus either rhu IL-3, rhu GM-CSF, or rhu G-CSF. Removal of adherent cells and T lymphocytes did not influence the synergistic activities of rhu IL-4. Rmu IL-4, synergized with rhu G-CSF, but not with rmu GM-CSF, rmu IL-3, or natural mu CSF-1, to enhance CFU-GM (mainly granulocyte) colony numbers by a greater than 90% pure preparation of murine CFU-GM. Also, rhu IL-4 at low concentrations enhanced release of CSF and at higher concentrations the release also of suppressor molecules from human monocytes and PHA-stimulated human T lymphocytes. Use of specific CSF antibodies suggested that rhu IL-4 was enhancing the release of G-CSF and CSF-1 from monocytes and the release of GM-CSF and possibly G-CSF from PHA-stimulated T lymphocytes. Use of antibodies for TNF-alpha, IFN-gamma, or TNF-beta as well as measurement of TNF and IFN titers suggested that the suppressor molecule(s) released from monocytes were acting with TNF-alpha and those released from PHA-stimulated T lymphocytes were acting with IFN-gamma. These results implicate B cell growth factor-1/IL-4 as a synergistic activity for hematopoietic progenitors and suggest that the actions can be on both progenitor and accessory cells.

Animals↗
PubMed1988

Temporal adaptation of neutrophil oxidative responsiveness to n-formyl-methionyl-leucyl-phenylalanine. Acceleration by granulocyte-macrophage colony stimulating factor.

This investigation was undertaken to clarify the mechanism by which purified recombinant human granulocyte-macrophage colony stimulating factor (GM-CSF) potentiates neutrophil oxidative responses triggered by the chemotactic peptide, FMLP. Previous studies have shown that GM-CSF priming of neutrophil responses to FMLP is induced relatively slowly, requiring 90 to 120 min of incubation in vitro, is not associated with increased levels of cytoplasmic free Ca2+, but is associated with up-regulation of cell-surface FMLP receptors. We have confirmed these findings and further characterized the process of GM-CSF priming. We found that the effect of GM-CSF on neutrophil oxidative responsiveness was induced in a temperature-dependent manner and was not reversed when the cells were washed extensively to remove the growth factor before stimulation with FMLP. Extracellular Ca2+ was not required for functional enhancement by GM-CSF and GM-CSF alone effected no detectable alteration in the 32P-labeled phospholipid content of neutrophils during incubation in vitro. Our data indicate that GM-CSF exerts its influence on neutrophils by accelerating a process that occurs spontaneously and results in up-regulation of both cell-surface FMLP receptors and oxidative responsiveness to FMLP. Thus, the results demonstrate that, with respect to oxidative activation, circulating endstage polymorphonuclear leukocytes are nonresponsive or hyporesponsive to FMLP; functional responsiveness increases dramatically as surface FMLP receptors are gradually deployed after the cells leave the circulation. Thus, as neutrophils mature, their responsiveness to FMLP changes in a manner which may be crucial for efficient host defense. At 37 degrees C, this process is markedly potentiated by GM-CSF. We conclude that endogenous GM-CSF, released systemically or at sites of infection and inflammation, potentially plays an important role in host defense by accelerating functional maturation of responding polymorphonuclear leukocytes.

Cell Differentiation↗
PubMed1988

Effect of whole-body hyperthermia and cyclophosphamide on natural killer cell activity in murine erythroleukemia.

Mice infected with the polycythemia-inducing strain of Friend virus complex (FVC-P) develop a fatal erythroid disease similar in some respects to leukemia. Six- to eight-week-old DBA/2 female mice were injected i.v. with 0.5 ml of a virus suspension containing approximately 5 X 10(4) plaque-forming units and 5 X 10(3) spleen focus-forming units. Four treatment regimens were begun 3 days postinjection: (a) no treatment; (b) whole-body hyperthermia (WBH) alone; (c) cyclophosphamide (CY) alone; (d) WBH combined with CY. WBH treatment utilized a microwave generator operating at 2450 MHz. The i.p. temperature of the mice receiving WBH was maintained at 39.5-40 degrees C for 30 min. The CY was given i.p. at a dosage of 20 mg/kg of body weight. The various treatments, CY, WBH, CY + WBH were given once a week for 2 weeks. Natural killer cell activity was examined in all four groups of mice and was found to be significantly higher in the animals treated with WBH or CY. Our results show that WBH, either alone or in combination with CY, can prolong the lifespan of mice infected with lethal dosages of the FVC-P, possibly via a mechanism involving natural killer cells.

Animals↗
PubMed1988

Enhancement of release of granulocyte- and granulocyte-macrophage colony-stimulating factors from phytohemagglutinin-stimulated sorted subsets of human T lymphocytes by recombinant human tumor necrosis factor-alpha. Synergism with recombinant human IFN-gamma.

The influence of purified recombinant human TNF-alpha (rhuTNF-alpha) was assessed, alone and in combination with purified recombinant human IFN-gamma (rhuIFN-gamma), for its effects on enhancing release from human T lymphocytes of activities that stimulate colony formation by granulocyte-macrophage, erythroid, and multipotential progenitor cells. rhuTNF-alpha or rhuIFN-gamma enhanced the release of CSF, which were determined to be granulocyte-CSF and granulocyte-macrophage-CSF by human bone marrow colony assays, morphologic assessment of colony types, and neutralization studies with rabbit anti-human granulocyte-CSF and monoclonal mouse anti-human granulocyte-macrophage-CSF. The CSF were released only when PHA was used, whether or not rhuTNF-alpha and/or rhuIFN-gamma were present while the lymphocytes conditioned the medium. T lymphocytes were sorted into subsets by using three-color immunofluorescence and a dye laser flow cytometry system with cells incubated with biotin anti-Leu-4 labeled with Texas Red, FITC-conjugated anti-Leu-3a, and phycoerythrin-conjugated anti-Leu-2a. Both the Leu-4+3a+2a- and the Leu-4+2a+3a- cells released CSF in response to PHA, but the release of CSF from PHA-stimulated lymphocytes was enhanced by rhuTNF-alpha and rhuIFN-gamma only from the Leu-4+3a+2a- subset of cells. Use of the three-color cell sorting made it highly unlikely that NK cells were involved, because both sorted subsets were positive for Leu-4. rhuTNF-alpha and rhuIFN-gamma synergized to enhance release of CSF such that low concentrations of each molecule, which were inactive when used alone, were active when the two molecules were used together. These studies suggest a role, at least in vitro, for TNF-alpha and IFN-gamma in the release of CSF from subsets of T lymphocytes stimulated with PHA.

Adjuvants, Immunologic↗
PubMed1988

Curative effect of split low dosage total-body irradiation on mice infected with the polycythemia-inducing strain of the Friend virus complex.

Split low dose total-body irradiation (TBI) with 150 cGy was assessed for its efficacy in modifying the disease induced in DBA/2 mice by the polycythemia-inducing strain of the Friend virus complex (FVC-P, composed of a Friend murine leukemia helper virus and a spleen focus-forming virus). All FVC-P injected mice were dead within 40 days; however, infected mice receiving TBI on days 5 and 12 exhibited long-term survival. FVC-P-injected mice receiving TBI treatment on days 5 and 12 had normal leukocyte counts, normal spleen weights, and no detectable spleen focus-forming virus. Although the FVC-P-infected mice had decreased proportions of L3T4+ cells and increased proportions of Lyt-2+ cells, these were returned to normal following TBI treatment. Apparently the time sequence of TBI treatments is important since one treatment with TBI on day 5, or two treatments with TBI on days 12 and 18, was not as efficacious. The inability of in vitro irradiation doses of up to 1000 cGy to inactivate FVC-P which was subsequently injected into murine hosts suggests that the effectiveness of the TBI treatment in vivo is not due to a direct radiation effect on the virus. These results indicate a possible relationship between L3T4+ and Lyt-2+ numbers or their ratio in the curative efficacy of TBI in FVC-P-infected mice.

Animals↗
PubMed1988

Effects of hematopoietic suppressor molecules on the in vitro proliferation of purified murine granulocyte-macrophage progenitor cells.

Highly purified murine granulocyte-macrophage progenitor cells (CFU-GM) were used as target cells to assess the possible direct effects of purified preparations of recombinant murine gamma-interferon, prostaglandin E, recombinant human heavy chain (acidic) ferritin, and recombinant human tumor necrosis factor alpha (TNF-alpha) on progenitor cells in vitro. Target CFU-GM, with cloning efficiencies of up to 84% and containing 0-3% morphologically recognizable accessory cells at the initiation of the culture period, were plated at a density of 100-150 cells/dish in the presence or absence of pure suppressor molecules. Colony formation was stimulated with either crude pokeweed mitogen-stimulated mouse spleen conditioned medium, pure natural murine macrophage colony-stimulating factor, or pure recombinant murine granulocyte-macrophage colony-stimulating factor. All four suppressor molecules were active in vitro against purified CFU-GM as assessed by their ability to inhibit colony or cluster formation. No apparent difference in the degree of responsiveness to prostaglandin E, gamma-interferon, or human heavy chain (acidic) ferritin was noted in the presence of pokeweed mitogen-stimulated mouse spleen conditioned medium, granulocyte-macrophage colony-stimulating factor, or macrophage colony-stimulating factor. In contrast, TNF-alpha in cultures containing macrophage colony-stimulating factor slightly, but significantly, potentiated colony formation. TNF-alpha also appeared more active at suppressing colony formation at lower concentrations in pokeweed mitogen-stimulated mouse spleen conditioned medium than in granulocyte-macrophage colony-stimulating factor-stimulated cultures of purified CFU-GM. The results suggest that TNF-alpha, human heavy chain (acidic) ferritin, gamma-interferon, and prostaglandin E can act directly at the progenitor cell level.

Animals↗
PubMed1988

Recombinant human tumor necrosis factors alpha and beta stimulate fibroblasts to produce hemopoietic growth factors in vitro.

The influences of TNF alpha and TNF beta were evaluated for their stimulatory and inhibitory effects on in vitro colony formation by human bone marrow granulocyte-macrophage (CFU-GM), erythroid (BFU-E), and multipotential (CFU-GEMM) progenitor cells. Both TNF alpha and TNF beta induced fibroblasts to produce stimulators of CFU-GM, BFU-E, and CFU-GEMM in a dose-dependent fashion. Similar results were seen when equivalent concentrations of TNF alpha and TNF beta were used. Prior incubation of the TNF alpha and TNF beta with their respective antibodies inactivated the ability of the TNF preparations to induce the release of granulocyte-macrophage, erythroid, and multipotential colony-stimulating activity from fibroblasts. In addition, incubation of the TNF-induced fibroblast supernatant with antibody before colony assay resulted in enhanced colony formation, suggesting that the TNF carried over into the colony assay suppressed colony formation. Additional proof of this suppression by TNF was evident when TNF was added directly to the CFU-GM, BFU-E, and CFU-GEMM colony assays. IL-1 does not appear to function as an intermediary in growth factor production by fibroblasts stimulated with TNF because antibody to IL-1 displayed no effect. Furthermore, assay of TNF-induced fibroblast supernatant was negative for IL-1. These results suggest that TNF alpha and TNF beta exert both a positive and negative influence on in vitro hemopoietic colony formation.

Bone Marrow Cells↗
PubMed1988

Recombinant human granulocyte-colony stimulating factor and recombinant human macrophage-colony stimulating factor synergize in vivo to enhance proliferation of granulocyte-macrophage, erythroid, and multipotential progenitor cells in mice.

Combinations of low dosages of purified recombinant human (rh) macrophage-colony stimulating factor (M-CSF; also termed CSF-1) and rh granulocyte-colony stimulating factor (G-CSF) were compared alone and in combination for their influence on the cycling rates and numbers of bone marrow and splenic granulocyte-macrophage, erythroid, and multipotential progenitor cells in vivo in mice pretreated with iron-saturated human lactoferrin (LF). LF was used to enhance detection of the stimulating effects of exogenously added CSFs. Concentrations of each CSF that were not active in vivo when given alone were active when given together, with the other CSF. The concentrations of rhM-CSF and rhG-CSF needed to increase progenitor cell cycling in the marrow and spleen were reduced by factors of 40-200 when these CSFs were administered in combination with low dosages of the other CSF. At the concentrations of rhM-CSF and rhG-CSF tested, synergism was not noted on absolute numbers of progenitor cells or total nucleated cell counts per organ or circulating in the blood. These findings may have potential relevance when considered in a clinical setting where the CSFs might be used in combination with other biotherapy and/or chemotherapy.

Animals↗
PubMed1988

The production of myeloid blood cells and their regulation during health and disease.

The regulation of myelopoiesis in vivo most likely entails a complex set of interactions between cell-derived biomolecules and their target cells: hematopoietic stem and progenitor cells and accessory cells. Stimulating and suppressing factors have been characterized through in vitro studies, and their mechanisms of action in vitro and in vivo have begun to be elucidated. Among those factors being studied are the hematopoietic colony-stimulating factors (CSF): interleukin-3 (multi-CSF), granulocyte-macrophage-CSF, granulocyte-CSF, and macrophage-CSF; other molecules include erythropoietin, B-cell-stimulating factor-1, interleukin-1, interleukin-2, prostaglandin E, leukotrienes, acidic ferritins, lactoferrin, transferrin, the interferons-gamma, -alpha, and -beta, and the tumor necrosis factors-alpha and -beta (lymphotoxin). These factors interact to modulate blood cell production in vitro and in vivo. The proposed review characterizes these biomolecules biochemically and functionally, including receptor-ligand interactions and the secondary messengers within the cell which mediate their functional activity. The production and action of the molecules are described under conditions of hematopoietic disorders, as well as under normal conditions. Studies in vitro are correlated with studies in vivo using animal models to give an overall view of what is known about these molecules and their relevance physiologically and pathologically.

Animals↗
PubMed1988

Purified murine granulocyte/macrophage progenitor cells express a high-affinity receptor for recombinant murine granulocyte/macrophage colony-stimulating factor.

Purified recombinant murine granulocyte/macrophage colony-stimulating factor (GM-CSF) was labeled with 125I and used to examine the GM-CSF receptor on unfractionated normal murine bone marrow cells, casein-induced peritoneal exudate cells, and highly purified murine granulocyte/macrophage progenitor cells (CFU-GM). CFU-GM were isolated from cyclophosphamide-treated mice by Ficoll-Hypaque density centrifugation followed by counterflow centrifugal elutriation. The resulting population had a cloning efficiency of 62-99% in cultures containing conditioned medium from pokeweed mitogen-stimulated spleen cells and 55-86% in the presence of a plateau concentration of purified recombinant murine GM-CSF. Equilibrium binding studies with 125I-labeled GM-CSF showed that normal bone marrow cells, casein-induced peritoneal exudate cells, and purified CFU-GM had a single class of high-affinity receptor with an approximate Ka of 10(8)-10(9) M-1. CFU-GM expressed an average of 3783 +/- 4 receptors per cell; normal bone marrow cells, 1518 +/- 242 receptors per cell; and peritoneal exudate cells, 2025 +/- 216 receptors per cell. Affinity crosslinking studies demonstrated that 125I-labeled GM-CSF bound specifically to two species of Mr 180,000 and 70,000 on CFU-GM, normal bone marrow cells, and peritoneal exudate cells. The Mr 70,000 species is thought to be a proteolytic fragment of the intact Mr 180,000 receptor. The present studies indicate that the GM-CSF receptor expressed on CFU-GM and mature myeloid cells are structurally similar. In addition, the number of GM-CSF receptors on CFU-GM is twice the average number of receptors on casein-induced mature myeloid cells, suggesting that receptor number may decrease as CFU-GM mature.

Animals↗