Different haematopoietic growth factors have different capacity in overcoming the in vitro interferon gamma-induced suppression of bone marrow progenitor cells

Interferon gamma (IFN gamma) inhibits haematopoiesis in vitro and an in vivo role in bone marrow suppression has been implied from clinical studies. We investigated the capacity of three recombinant (r), human (h), haematopoietic growth factors to overcome the in vitro IFN gamma inhibition of bone marrow progenitor cells in a methylcellulose culture system. Granulocyte macrophage-colony stimulating factor (GM-CSF) partially reversed IFN gamma-induced suppression of granulocyte-macrophage colony formation, by increasing colony forming units-granulocyte macrophage (CFU-GM) in a proportion ranging from 54-101%. Interleukin-3 (IL-3) and granulocyte-colony stimulating factor (G-CSF) were much less effective. For erythropoiesis, IL-3 was much more effective and partially reversed IFN gamma-mediated inhibition by increasing burst forming units-erythroid (BFU-E) in a proportion ranging from 52-138%. GM-CSF and G-CSF had no significant effect on IFN gamma-induced suppression of BFU-E. In conclusion, haematopoietic growth factors have different capacity to overcome IFN gamma-induced suppression of marrow progenitor cells in vitro. The findings may have therapeutic implications, as combinations of growth factors may be more effective in treating bone marrow failure syndromes.

Hematopoietic growth factors--an overview

The hematopoietic growth factors are a family of glycoprotein hormones that regulate hematopoietic cell proliferation and mature blood cell function. The list of colony-stimulating factors and interleukins known to stimulate blood cell production is now quite long; these hormones are produced in quantity by recombinant molecular methodologies and most have entered clinical trials. We will shortly have the power to regulate the numbers and function of the circulating blood cells, and the challenge of the coming decade will be in dissecting how these growth factors can be used optimally in therapeutic practice. A central theme of their use will be the enhancement of host defense, opening an area of medical therapy of great potential to reduce the morbidity and mortality of cancer, infectious diseases and immune deficiency states.

Colony-stimulating factors

The colony-stimulating factors (CSFs) are hematopoietic growth factors (HGFs) involved in regulating the formation of nonlymphoid blood cells. A brief review of the different types of CSFs and their biological properties is presented. The current nomenclature of CSFs and other HGFs is confused by the use of terms and abbreviations based on particular effects on target cells. However, a given cell is frequently recognized by more than one HGF/CSF, and a given HGF/CSF may recognize different types of target cells, including in some cases nonhematopoietic cells. A number-based nomenclature is universally used for the interleukins. Since the macrophage CSF (M-CSF) and the granulocyte-macrophage CSF (GM-CSF) have been designated previously as CSF-1 and CSF-2, respectively, the author proposes the designation of the granulocyte CSF (G-CSF) as CSF-3.

Interactions of hemopoietic cytokines on differentiation of HL-60 cells. Nerve growth factor is a basophilic lineage-specific co-factor

Nerve growth factor (NGF) is a neurotropic polypeptide which has broad biological activity other than support of growth and survival of sympathetic, sensory and central neurons. NGF promotes rat mast cell hyperplasia in vivo and human granulopoiesis in vitro, selectively augmenting basophil/mast cell differentiation in the presence of T cells or conditioned medium derived from a human T cell line (Mo-CM), a source of granulocyte-macrophage colony-stimulating factor (GM-CSF). NGF also synergizes with GM-CSF to promote human basophil/mast cell differentiation in both methylcellulose and suspension cultures of myeloid progenitors. In the current studies, we examined the interactions of NGF and several cytokines considered to be involved in human basophil/mast cell and eosinophil growth and differentiation, including interleukin (IL)-3, IL-4, IL-5, GM-CSF and granulocyte colony-stimulating factor (G-CSF). NGF synergistically enhanced IL-5 induced dose-dependent increases in histamine content and basophilic cell differentiation of myeloid leukemic HL-60 cells, but was only additive to similar effects of IL-3. In contrast, IL-4 and G-CSF did not promote basophilic differentiation of HL-60 cells in the presence or absence of NGF. Various combinations of GM-CSF, G-CSF, IL-3, IL-4 and IL-5 could not reproduce the synergy observed between NGF and either IL-5 or GM-CSF. NGF appears to represent a class of lineage-specific co-factors, in this case being involved in GM-CSF- or IL-5-induced basophilic lineage differentiation, thus contributing to tissue inflammation or repair.

Synergistic interactions allow colony formation in vitro by murine haemopoietic stem cells

A clonogenic assay for cells that give rise to macroscopic colonies in agar or methyl cellulose cultures using untreated, normal murine bone marrow as a source of stem cells is described. We have characterized the clonogenic cell, which has been designated CFU-A, by comparing its properties with those of multipotential stem cells (assayed as CFU-S) and lineage-restricted progenitor cells (assayed as GM-CFC). The investigations have included assessment of proliferative status and response to CFU-S proliferation regulators, response to 5-fluorouracil, buoyant cell density, radial distribution in the femur and response to ionizing radiation. We conclude that the CFU-A has properties in common with CFU-S that differ from those of GM-CFC. The data are consistent with the CFU-A assay detecting part of the multipotential stem cell population also detected by spleen colony formation.

Interleukin-1 is identical to hemopoietin-1: studies on its therapeutic effects on myelopoiesis and lymphopoiesis

Conditioned medium from the human tumor cell line HBT 5637 possesses a unique hematopoietic activity, originally termed hemopoietin-1. Hemopoietin-1 alone does not stimulate bone marrow colony formation or proliferative responses in vitro, but rather potentiates responses to other hematopoietic growth factors, such as CSF-1 and GM-CSF. In studies designed to characterize the molecular nature of this factor, it was found by molecular, biochemical biological and serological criteria that all the hemopoietin-1 like activity could be attributed to IL-1 alpha. The therapeutic potential of IL-1 was then tested in a system where myelopoiesis is depressed by whole body irradiation. After 750 R irradiation, mice were administered IL-1 twice daily for the duration of the experiment. Mice which received IL-1 treatment had an accelerated recovery of marrow colony forming capacity which was also reflected by significantly higher blood neutrophil levels as compared to control irradiated mice. IL-1 treated irradiated mice also had a significant increase in resistance to bacterial challenge 14 days post irradiation. Thus, IL-1 treatment was effective in augmenting myelopoiesis following sublethal whole body irradiation. The effects of the IL-1 treatment on the recovery of lymphocyte numbers was also assessed. Here the IL-1 treated irradiated mice had fewer lymphocytes and depressed mitogen responses by spleen cells. Indeed the thymus of the IL-1 treated irradiated mice remained chronically hypoplastic for the duration of the experiment. Although IL-1 treatment increased myeloid progenitors in the bone marrow, it caused a decrease in the frequency of pre-B cells. Thus, IL-1 administration is an effective treatment for accelerating myeloid recovery following the cytoreductive effects of irradiation, but the myelopoietic augmentation may be at the expense of lymphoid recovery.

Translation of poly(A)+ mRNA encoding CFU-S proliferation stimulator of human fetal liver origin in Xenopus laevis oocytes

Using the sodium dodecyl sulfate/chloroform/phenol method, total RNA was extracted from human fetal liver tissue with a yield of 870-1060 micrograms/g of tissue; mRNA was obtained after chromatography on an oligo(dT)-cellulose column. Experimental studies demonstrated the translation of a poly(A)+ mRNA encoding proliferation stimulator of human fetal liver origin in Xenopus laevis oocytes.

Identification of a common signal associated with cellular proliferation stimulated by four haemopoietic growth factors in a highly enriched population of granulocyte/macrophage colony-forming cells

We have prepared a population of bone marrow cells that is highly enriched in neutrophil/macrophage progenitor cells (GM-CFC). Four distinct haemopoietic growth factors can stimulate the formation of mature cells from this population, although the proportions of neutrophils and/or macrophages produced varied depending on the growth factor employed: interleukin 3 (IL-3) and granulocyte/macrophage colony-stimulating factor (GM-CSF) stimulated the formation of colonies containing both neutrophils and macrophages; macrophage colony-stimulating factor (M-CSF) produced predominantly macrophage colonies; and granulocyte colony-stimulating factor (G-CSF) promoted neutrophil colony formation. Combinations of these four growth factors did not lead to any additive or synergistic effect on the number of colonies produced in clonal soft agar assays, indicating the presence of a common set of cells responsive to all four haemopoietic growth factors. These enriched progenitor cells therefore represent an ideal population to study myeloid growth-factor-stimulated survival, proliferation and development. Using this population we have examined the molecular signalling mechanisms associated with progenitor cell proliferation. We have shown that modulation of cyclic AMP levels has no apparent role in GM-CFC proliferation, whereas phorbol esters and/or Ca2+ ionophore can stimulate DNA synthesis, indicating a possible role for protein kinase C activation and increased cytosolic Ca2+ levels in the proliferation of these cells. The lack of ability of all four myeloid growth factors to mobilize intracellular Ca2+ infers that these effects are not achieved via inositol lipid hydrolysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical use of recombinant human hematopoietic growth factors

Hematopoietic growth factors comprise a family of hematopoietic regulators with biologic specificities defined by their ability to support proliferation and differentiation of blood cells of different lineages. The biologic specificities of these factors are highly complex, dose dependent, and frequently overlapping. Recent advances in the cloning of hematopoietic growth factor genes and the availability of recombinant material have led investigators to conduct clinical trials with these agents. Some of these factors have been studied and used in chemotherapy-induced neutropenia, myelodysplastic syndromes, and bone marrow failure syndromes. In this paper, we review the experience with growth factors that have been tested and that currently are being introduced in clinical trials. In addition, we report some factors with possible future interest for clinicians and researchers.

Abnormal megakaryopoiesis in patients with myelodysplastic syndromes: analysis of cellular and humoral defects

In 13 patients with myelodysplastic syndrome (MDS) mature and immature erythropoietic (CFU-E, BFU-E), granulopoietic (CFU-GM) and megakaryopoietic (CFU-Meg) colony formation from human bone marrow mononuclear cells was evaluated in a microagar culture system. All but three patients exhibited abnormal CFU-Meg. The defect of CFU-Meg paralleled the reduction of BFU-E, whereas CFU-GM number declined to a lesser extent. Not only the CFU-Meg number, but also the number of megakaryocytes (Mk) per colony was reduced suggesting an additional functional CFU-Meg defect. Megakaryocytic growth factor (Meg-CSF) abnormalities in MDS patients were detected using normal nonadherent T-lymphocyte depleted bone marrow cells as target cells for serum testing. Even for sera from patients with a reduction of platelets and bone marrow megakaryocytes Meg-CSF levels were not increased. No cellular or humoral inhibition could be detected in an MDS patient with a 5q- karyotype, who had an isolated defect of the megakaryocytic cell lineage at presentation. Some patients revealed a spontaneous formation of mixed erythrocytic, granulocytic and megakaryocytic clusters in the presence of fetal calf serum or autologous patient serum, probably representing autonomous proliferation of the malignant clone. In conclusion, both cellular and humoral factors can cause abnormalities of the megakaryocytic cell lineage in MDS patients.

Human vascular endothelial cells, granulopoiesis, and the inflammatory response

We have carried out a series of in vitro studies designed to characterize the role of mononuclear phagocytes as regulators of hematopoiesis. The results of these studies have demonstrated that mononuclear phagocytes produce factors, including interleukin-1 (IL-1), that induce the expression of multilineage hematopoietic growth factors by human vascular endothelial cells. In more recent studies we and others have identified these induced factors as G-CSF, GM-CSF, IL-6, and IL-1. Interleukin 1 stimulates expression of these genes by inducing the accumulation of gene transcripts. Moreover, transcript accumulation, at least with GM-CSF, results from prolongation of mRNA half-life. Based on preliminary studies in a cell-free system, we propose that the inductive capacity of IL-1 results from its activation of ribonuclease inhibitors in the cytoplasm of IL-1-induced cells and hypothesize that this may be a general mechanism by which IL-1 induces gene expression.

Influence of IL-1 alpha and -1 beta on the survival of human bone marrow cells responding to hematopoietic colony-stimulating factors

Purified recombinant human (rhu) IL-1 alpha and IL-1 beta were evaluated for their effects on the proliferation and survival of granulocyte-macrophage (CFU-GM) and erythroid (BFU-E) progenitor cells from normal human bone marrow (BM). Using nonadherent low density T lymphocyte depleted (NALT-) BM cells cultured in the presence or absence of IL-1, CSF-deprivation studies demonstrated that IL-1 alpha or IL-1 beta by itself did not enhance the proliferation of CFU-GM or BFU-E. They did, however, promote the survival of progenitors responding to the delayed addition of media conditioned by the 5637 cell line (5637 conditioned medium), rhu GM-CSF and erythropoietin. The survival promoting effects of IL-1 alpha on CFU-GM and BFU-E were neutralized by anti-IL-1 alpha mAb added to the cultures. The survival promoting effect of IL-1 alpha did not appear to be mediated by CSF, because neither CSF nor erythroid burst promoting activity were detectable in cultures in which NALT- cells were incubated with rhuIL-1 alpha. In addition, suboptimal concentrations of rhu macrophage CSF (CSF-1), G-CSF, GM-CSF, and IL-3, which were just below the levels that would stimulate colony formation, did not enhance progenitor cell survival. Survival of CFU-GM and BFU-E in low density (LD) bone marrow cells did not decrease as drastically as that in NALT- BM cells, and exogenously added IL-1 did not enhance progenitor cell survival of CFU-GM and BFU-E in LD BM cells. However, addition of anti-IL-1 beta decreased survival of CFU-GM and BFU-E in LD BM cells. These results implicate IL-1 in the prolonged survival of human CFU-GM and BFU-E.

Hematopoietic growth factor production by cultured cells of human nasal polyp epithelial scrapings: kinetics, cell source, and relationship to clinical status

The conditions and cell sources for colony stimulating activity (CSA) production by nasal polyp epithelial scrapings were examined. Epithelial scrapings removed from patients were grown to confluence during 7 days as monolayers of epithelial cells in media supplemented with fetal calf serum (FCS) on collagen-coated microwell plates. Growth kinetics of nasal polyp epithelial cells (NPECs) were determined, and CSA in NPEC conditioned medium (CM) was assessed with density-gradient separated, nonadherent peripheral blood mononuclear cells in standard 14-day methylcellulose assays. Nasal polyp cultures in the presence of 5% or 15% FCS (vol/vol) demonstrated significantly more epithelial cell proliferation than cultures at 0% and 1% FCS. There were comparable metachromatic cell counts in polyp epithelial scrappings from allergic and nonallergic donors. Similarly, NPEC CM from allergic and nonallergic donors had equivalent CSA for basophil/mast cell (BMC) and eosinophil (EO) lineages, respectively. CSA production was enhanced under conditions of higher FCS concentration and NPEC proliferation. These studies confirm an epithelial cell origin of BMC and EO growth and differentiation factors derived from nasal polyps and point to the existence of a unique microenvironment for BMC and EO development provided by polyp epithelium that appears to be independent of the presence of an allergic diathesis.

The growth of Rauscher erythroleukemia cells is mediated by autocrine production of a factor with biological activity similar to interleukin-3

Under serum-deprived and chemically defined culture conditions, the growth of Rauscher erythroleukemia cells is mediated by an autocrine mechanism. The growth-promoting activity is produced by fresh or irradiated cells and resembles the activity of interleukin-3 (IL-3) in its ability to sustain colony formation from three of four IL-3-dependent cell lines and to induce formation of granulocyte/macrophage (GM) colonies and, in the presence of erythropoietin (Ep), of erythroid bursts and mixed erythroid colonies. IL-3, IL-1, IL-4, IL-6, GM colony-stimulating factor (GM-CSF), G-CSF, M-CSF, Ep, and media conditioned by concanavalin A-stimulated mouse spleen cells or phytohemagglutinin-stimulated LBRM 33 cells were unable to induce proliferation of the Rauscher erythroleukemia cells. Northern analysis of total and polyA-selected RNA extracted from untreated Rauscher cells or from cells 24 hours after irradiation showed the presence of message for M-CSF but not for IL-3, IL-1, GM-CSF, or G-CSF. The production of IL-6 was excluded by a sensitive bioassay. These results indicate that the autocrine growth of the Rauscher cell line is mediated by a growth factor different from IL-3, but with similar biological activity. Activation of the expression of such a growth factor during viral infection may contribute to the generation of leukemic cells that have the property to grow in vitro and generate Rauscher erythroleukemia cell lines.

Interleukin-6 interacts with interleukin-4 and other hematopoietic growth factors to selectively enhance the growth of megakaryocytic, erythroid, myeloid, and multipotential progenitor cells

The growth-promoting activities of interleukin-6 (IL-6) in combination with different factors were assessed in bone marrow (BM) cultures prepared from normal mice and from mice treated with 5-fluorouracil (5-FU). Effects on hematopoietic colony formation with respect to number, size, and cellular composition were evaluated. In agreement with previous reports, IL-6 acts synergistically with IL-3 to stimulate increased numbers of granulocyte/macrophage (GM) and multilineage colonies in day-2 and day-4 post-5-FU BM cultures. Furthermore, day 4 but not day 2 post-5-FU BM showed enhanced GM colony formation when stimulated with IL-6 plus interleukin-4 (IL-4) or granulocyte colony-stimulating factor (G-CSF). In contrast, IL-6 did not increase the number of colonies supported by M-CSF or GM-CSF. Nevertheless IL-6 interacted with all factors, including M-CSF and GM-CSF, to stimulate an increase in colony size. Many of these myeloid colonies attained a diameter of greater than or equal to 0.5 mm, suggesting they derive from high proliferative potential cells (HPP-CFC). The response of normal and day-8 post-5-FU BM containing high numbers of more mature progenitors was also assessed. We found IL-6 enhanced colony formation by lineage-restricted megakaryocytic and erythroid progenitors in the presence of IL-3 and IL-4 plus erythropoietin (Epo), respectively. The sum of these results shows that IL-6 interacts with a variety of factors to regulate the growth of progenitor cells at different stages of lineage commitment and maturation.

Introduction and overview of hematopoietic growth factors

Blood cell development is regulated by a variety of hematopoietic growth factors that mediate the growth, maturation, and activation of hematopoietic cell elements. Several of these factors have been isolated and are now being produced by means of recombinant DNA techniques in quantities sufficient for study and clinical use. Three factors in particular have recently received considerable attention in the clinical arena: recombinant human granulocyte colony-stimulating factor (G-CSF), granulocyte macrophage colony-stimulating factor (GM-CSF), and erythropoietin (EPO). Although both may prove to be clinically useful, G-CSF and GM-CSF have distinct and different biological characteristics. The regulatory action of G-CSF is apparently lineage-specific for the proliferation and maturation of neutrophil granulocytes. GM-CSF is less restricted in its actions, affecting all granulocytes, especially eosinophil granulocytes. It also stimulates the proliferation and activation of monocyte-macrophages and induces these cells to produce a number of cytokines. EPO mediates the growth of erythroid progenitors into mature erythrocytes. The CSFs and EPO have many potential clinical applications, including enhancing myeloid effector cell production and function, rendering malignant cells more susceptible to killing by cycle-specific agents, and correcting the anemia of end-stage renal disease.

Haemopoietic growth factors: their role in acute myeloblastic leukaemia

The chromosome alterations specifically associated with leukaemia are found largely in the regions where the genes for the haemopoietic growth factors (as well as other regulatory molecules or their receptors) are located, indicating a crucial role of the growth factors in leukaemogenesis. However, growth factor genes per se do not generally induce leukaemia when inserted into normal haemopoietic cells, although they will do so if they are inserted into immortalized haemopoietic stem cell lines. The response of AML cells to these growth factors is extremely heterogeneous, and the tilting of the balance between self-reproduction (leading to perpetuation of the leukaemic process) and differentiation ('death' of the malignant cells) depends on several parameters, on the type and combination of factors to which the cells are exposed, with IL-3 and GM-CSF tending to favour self-renewal, and G-CSF and M-CSF tending to favour differentiation. These findings open the possibility to consider the use of growth factors to control the leukaemic process, although such treatment should be approached with considerable caution, and on an individual patient basis.