Regulation of colony-stimulating activity production. Interactions of fibroblasts, mononuclear phagocytes, and lactoferrin

Enhanced clearance of Escherichia coli and Staphylococcus aureus in mice treated with cyclophosphamide and lactoferrin

Previous studies on cyclophosphamide (CP)-immunocompromised mice showed accelerated reconstitution of immune system function following oral treatment with lactoferrin (LF). The aim of this investigation was to evaluate the ability of mice, treated with a sublethal dose of CP and given LF, to combat bacterial infections. Mice were injected with a single, intraperitoneal dose of CP (350 mg/kg body weight). One group of CP-treated mice was also given LF in drinking water (0.5% solution) for 14 days. Untreated and LF-treated mice served as controls. On day 15 following CP administration, mice were infected intravenously with 10(8) Escherichia coli or 5 x 10(7) Staphylococcus aureus. Twenty-four hours later, the number of colony-forming units (CFU) in spleens and livers were determined. Phenotypic analysis of blood leukocytes was determined, as well as the ability of splenic and peritoneal cells to produce IL-6 spontaneously and in the presence of lipopolysaccharide (LPS). Treatment with CP, or with CP and LF, led to profound reduction of E. coli CFU in the liver and the spleen; treatment with LF alone had significant inhibitory effects on organ enumerated CFU. S. aureus CFUs were also significantly reduced in spleens of mice treated with CP or CP/LF and, to a lesser degree, after LF alone. These effects were also significantly reduced in the livers. Analysis of blood cellular phenotype revealed total number of peripheral leukocytes was lower in the CP-treated group (52.6%) but not significantly different from control values in CP/LF and LF-treated groups (90.7% and 104.6%, respectively). Conversely, percentage of blood neutrophils was markedly elevated in CP and CP/LF groups--62% and 42.5% vs. 18.4% in controls. These findings were accompanied by production of IL-6 by splenic and peritoneal cells which was significantly increased in CP- and CP/LF-treated groups. It was concluded that the increased clearance of bacteria in the organs of mice treated with CP and CP/LF may result from a rise in the number of neutrophils infiltrating the organs and contributing to accelerated clearance of bacteria. The study also suggests that the ability of cells from CP- and CP/LF-treated mice to produce significantly more IL-6 may also contribute to increased resistance to infections. Lastly, together with our previous data, this study indicates that LF used to reconstitute the antigen-specific immune response in CP-treated mice does not impair their resistance to infection.

Reconstitution of the cellular immune response by lactoferrin in cyclophosphamide-treated mice is correlated with renewal of T cell compartment

Cyclophosphamide is an alkylating agent used to treat both malignant and non-malignant immune-mediated inflammatory disorders in humans. It is also known as a potent immunosuppressive drug in humans and experimental animals. The aim of this study was to evaluate the effects of oral administration of lactoferrin (LF) on cellular responses and reconstruction of the lymphocyte pool in mice treated with cyclophosphamide (CP). Twelve week-old CBA mice were given a single intraperitoneal (i.p.) dose of CP (400 mg/kg body weight), then were treated per os with seven doses of LF (1 mg/dose) on alternate days. We demonstrated that the magnitude of delayed type hypersensitivity to ovalbumin, strongly diminished by CP action, was reconstituted by LF. Oral LF treatment also resulted in partial recovery of Concanavalin A-induced splenocyte proliferation. Blood profile analysis revealed elevation of leukocytosis by LF in CP-treated mice (from 64.9 to 84.76% of the control value). LF also caused substantial restoration of the percentage of the lymphocyte population in circulating blood (from 43.4 to 60.2% of the control values). LF alone had no effect on the neutrophil/lymphocyte ratio in normal mice, however, the total number of leukocytes decreased by 23.25%. Furthermore, we showed that LF increased the cellularity of spleens isolated from CP-treated mice (from 53.2 to 78.8%) and the content of peritoneal and alveolar macrophages (elevations from 50.6 to 67.3% and from 65.2 to 83.6%, respectively). Lastly, using panning technique, we demonstrated that LF strongly elevated the pool of CD3+ T cells in normal and CP-immunocompromised mice and CD4+ T cell content. In conclusion, we showed for the first time that lactoferrin, given orally to CP-immunosuppressed mice, could reconstitute a T-cell mediated immune response by renewal of the T cell pool.

Orally administered lactoferrin restores humoral immune response in immunocompromised mice

Cyclophosphamide (CP) is an anti-tumor drug commonly used in the chemotherapy of human cancer and autoimmune diseases. In our previous studies, we have demonstrated that lactoferrin (LF), given orally to CP-immunosuppressed mice, could reconstitute a T cell mediated immune response by the renewal of the T cell population. The aim of this present study was to evaluate the effects of LF on humoral responses in mice treated with cyclophosphamide. We demonstrate that a single, sublethal dose of cyclophosphamide (400 mg/kg body weight) profoundly inhibited the humoral immune response of CBA mice to sheep red blood cells (SRBC), as measured by the number of antibody forming cells (AFC) in the spleen after 5 weeks following CP treatment. Administration of 0.5% bovine LF in drinking water for 5 weeks partially reconstituted the AFC number (30-40% of the control values, but 7-10x more than in CP-treated controls). Determination of T and B cell levels in the spleens by flow cytometry revealed that the content of CD3+ and CD4+ as well as Ig+ splenocytes was elevated in the immunocompromised mice treated with LF. In addition, the number of peritoneal macrophages was partially restored following LF treatment. Evaluation of the proliferative response to concanavalin A (ConA) and pokeweed mitogen (PWM) demonstrated that the diminished reactivity of splenocytes from CP-treated mice was significantly enhanced by LF. In summary, we conclude that the prolonged, oral treatment of immunocompromised mice with LF led to partial reconstitution of the humoral response, associated with elevation of T and B cell and macrophage content and the proliferative response of splenocytes to mitogens.

Human lactoferrin activates transcription of IL-1beta gene in mammalian cells

Lactoferrin (Lf) has been suggested to play roles in primary defense against microbial infection and other cellular processes including immunomodulation. Lf is known to bind to DNA and implicated to activate transcription. In the present study, we demonstrated that Lf stimulated transcription of IL-1beta gene, one of natural genes containing putative Lf binding site (LBS) in the 5'-flanking sequences. K562 cells treated with a combination of Lf and PMA showed a synergistic induction in the level of IL-1beta mRNA over treatment with PMA alone. Synergistic stimulation of IL-1beta expression by Lf and PMA was also confirmed by IL-1beta/Luc reporter gene assays. Analysis of Lf domains revealed that the transcriptional domain of Lf is located within the N-terminal 90 amino acids, termed NIa and that the C-terminal half lobe lacked the transactivating activity. The NIa, the N-terminal half lobe as well as intact Lf stimulated transcription of IL-1beta gene in the transfected K562 cells along with PMA, while the C-terminal half lobe did not. Our results suggest that Lf may play some roles in transcription of IL-1beta gene and may also regulate transcription of other natural genes containing LBS.

Production of a macrophage growth factor(s) by a goldfish macrophage cell line and macrophages derived from goldfish kidney leukocytes

We recently established a spontaneously proliferating macrophage cell line from the goldfish (GMCL), and in this report demonstrate the production of a macrophage-specific growth factor(s) (MGFs) by these cells. The supernatants from GMCL cultures induced proliferation and differentiation of macrophage-like cells from kidney hematopoietic tissues of goldfish. Kidney leukocytes cultured at 6.25 x 10(4)cells/ml in the presence of GMCL-derived MGFs proliferated during two weeks of cultivation, whereas those cultured without the MGFs did not. Leukocytes cultured at higher densities (2.5 x 10(5) cells/ml) proliferated in the absence of exogenous growth factor, but not to the same extent as those stimulated with GMCL-derived MGFs, suggesting that kidney leukocytes may produce endogenous MGFs. At higher cell density (1 x 10(6) cells/ml), kidney leukocytes multiplied extensively over a two-week cultivation period in the absence of exogenous GMCL-derived MGFs. The supernatants from these cultures restored the proliferative ability of leukocytes cultured at low densities, providing direct evidence of MGFs production by kidney leukocytes. The predominant cell-type in cultures grown in the presence of GMCL or kidney leukocyte-MGFs was the macrophage based on the following criteria: (1) non-specific esterase staining; (2) morphologic similarity to GMCL; (3) phagocytosis of the bacterium, A. salmonicida; (4) production of reactive oxygen and nitrogen intermediates in response to stimulation with macrophage activating factors and/or bacterial lipopolysaccharide; and (5) flow cytometric analyses. Both in vitro-derived kidney macrophage (IVDKM) and GMCL cultures contained three distinct populations of cells, (determined by flow cytometry), suggesting that these macrophage cultures are comprised of cells arrested at distinct differentiation junctures in macrophage development. Production of MGFs by macrophages and kidney leukocytes may play an important role in regulating macrophage hematopoiesis in fish.

The regulation of GM-CSF is dependent on a complex interplay of multiple nuclear proteins

GM-CSF is an important mediator of hematopoiesis and its dysregulation may play a role in neoplastic and inflammatory conditions. Previous studies have demonstrated that GM-CSF production depends upon the accumulation of specific mRNA, which occurs by transcriptional and post-transcriptional mechanisms. In order to dissect the cis-acting sequences responsible for its regulation, we performed an extensive mutagenesis study spanning 54 nucleotides 5' of the GM-CSF coding region. Our analysis suggests that the previously-described functional elements of the GM-CSF promoter, kappa B and a repetitive CATTT/A motif, the former co-exists with an overlapping 9 nucleotide site which silences promoter activity, and the CATTT/A complex binds multiple polypeptides which differentially contribute to basal and inducible promoter activity. These two sites interact to provide tissue-appropriate and stimulus-specific promoter function. Using DNA-protein cross-linking and co-transfection studies, we demonstrate that the c-rel-related proteins p65 and p50 bind to the GM-CSF promoter and that p65 binding is primarily responsible for the enhancing effects at this site. In addition, we show that the GM-CSF kappa B decanucleotide is inadequate to provide full binding affinity; mutation of nucleotides flanking this site affect promoter function by altering NF-kappa B binding affinity. Together these results suggest that the transcriptional response of GM-CSF is dependent on a complex interplay of multiple DNA binding proteins.

Inhibition of the conversion of pre-interleukins-1 alpha and 1 beta to mature cytokines by p-benzoquinone, a metabolite of benzene

Chronic exposure of humans to benzene causes severe bone marrow cell depression leading to aplastic anemia. Marrow stromal macrophage dysfunction and deficient interleukin-1 production has been reported for patients with severe aplastic anemia. The stromal macrophage, a target of benzene toxicity, is involved in hematopoietic regulation through the synthesis of several cytokines including interleukin-1, which is required for production by stromal fibroblasts of a number of cytokines required for the survival of hematopoietic progenitor cells. We have previously demonstrated that hydroquinone, a major toxic metabolite of benzene in marrow, prevents the proteolytic conversion of 31 kDa pre-interleukin-1 alpha to the 17 kDa cytokine by calpain in purified murine stromal macrophages. Furthermore, stromal macrophages from benzene-treated mice produce the 31 kDa pre-interleukin-1 alpha when stimulated in culture with endotoxin, but cannot convert the precursor to interleukin-1 alpha. In this report, we show that 1,4-benzoquinone, the oxidation product of hydroquinone in the cell, causes a concentration-dependent inhibition of highly purified human platelet calpain with an IC50 of 3 microM. Hydroquinone also inhibits the processing of pre-interleukin-1 beta by interleukin-1 beta convertase. The addition of 2 microM hydroquinone to B1 cells that undergo autocrine stimulation by interleukin-1 beta resulted in the cessation of autocrine cell growth and interleukin-1 beta secretion into the culture medium, as determined by Western immunoblots of the culture supernatants. Purified converting enzyme treated with 3 microM benzoquinone was incapable of converting 31 kDa recombinant pre-interleukin-1 beta to the 17 kDa mature cytokine as analyzed by polyacrylamide gel electrophoresis and Western immunoblotting. These findings support our observations in a mouse model that benzene-induced bone marrow cell depression results from a lack of interleukin-1 alpha subsequent to an inhibition by benzoquinone of calpain, the protease required for converting pre-interleukin-1 alpha to active cytokine. The results may provide a basis for studying benzene-induced aplastic anemia in a mouse model.

Effect of macrophage colony-stimulating factor on anticryptococcal activity of bronchoalveolar macrophages: synergy with fluconazole for killing

The anticryptococcal activity of murine bronchoalveolar macrophages (BAM) and their synergy with fluconazole (FCZ) was studied. BAM cultured with tissue culture medium for 48 to 72 h were fungicidal (24 to 39%) in a 3-h killing assay. However, net killing of Cryptococcus neoformans did not continue when culture time was extended to 24 h, although BAM were fungistatic (88 to 98%). Treatment with macrophage colony-stimulating factor (M-CSF; 5,000 U/ml, 48 h) did not significantly increase BAM killing of a low challenge dose in 3-h assays compared with control BAM. However, M-CSF-treated BAM were significantly more fungistatic against higher challenge doses in the 3-h assays. FCZ was not fungicidal at 5 micrograms/ml but was highly fungistatic (98 and 99% at 24 and 48 h, respectively). M-CSF-treated BAM acted synergistically with FCZ (2.5 micrograms/ml) for significantly greater killing than control BAM, 55% versus 20% and 96% versus 45% at 24 h and 48 h, respectively. Killing by M-CSF BAM and FCZ (5.0 micrograms/ml) was significantly (P < 0.01) greater than that by control BAM and FCZ at 48 h. These findings indicate an important collaborative role for BAM and FCZ in killing C. neoformans, and this is enhanced by M-CSF.

Elevated levels of heme oxygenase-1 activity and mRNA in peripheral blood adherent cells of acquired immunodeficiency syndrome patients

Patients with the acquired immunodeficiency syndrome (AIDS) commonly develop hematological abnormalities, including anemia, leukopenia, and thrombocytopenia. Heme synthesis and heme degradation are critical to the maintenance of cellular heme homeostasis and to hematopoietic differentiation. We examined heme oxygenase activity and expression of the heme oxygenase gene in adherent cells (monocytes-macrophages) obtained from the peripheral blood of AIDS patients and normal controls. Heme oxygenase activity in normal control cells was 43 +/- 16 pmol bilirubin formed/4 x 10(5) cells/hr as compared to 133 +/- 30 pmol bilirubin formed/4 x 10(5) cells/hr in the AIDS patients. Via blot hybridization analysis with human heme oxygenase cDNA, heme oxygenase mRNA levels in cells of the normal and the AIDS patients were compared. Total RNA from normal cells displayed only weak hybridization with the cDNA probe. In contrast, cells from peripheral blood of the AIDS patients displayed marked increases over normal levels in heme oxygenase mRNA. Heme oxygenase activity could be substantially suppressed by the competitive inhibitor of the enzyme, Sn-mesoporphyrin. Elevated heme oxygenase activity in cells of AIDS patients could produce a decrease in cellular heme needed for transductional signalling for the growth factor network, which regulates the hematopoietic microenvironment, and for other metabolic purposes. Suppression of heme catabolism by inhibitors of this enzyme may thus be useful in potentiating erythropoietic responses in this disorder.

Regulation of macrophage colony-stimulating factor in liver fat-storing cells by peptide growth factors

Macrophage colony-stimulating factor (M-CSF) selectively promotes mononuclear phagocyte survival, proliferation, and differentiation. The production of this factor within the liver may be necessary to support the relatively long-term survival of circulating monocytes as they migrate into tissues and differentiate into macrophages. We studied the constitutive expression and the effects of platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF), and epidermal growth factor (EGF) on M-CSF mRNA levels and secretion of M-CSF in murine liver fat-storing cells (FSC), vascular pericytes likely involved in the development of liver fibrosis. By Northern analysis, using a murine M-CSF cDNA, FSC constitutively express two major transcripts of 4.4 and 2.2 kb, similar to those detected in mouse L cells, used as a control. Exposure to 10 ng/ml PDGF or bFGF increased M-CSF mRNA levels. Peak effects were observed at 3 and 6 h for PDGF and bFGF, respectively, returning to baseline levels by 12 h. Under basal conditions, detectable amounts of M-CSF, measured by radioimmunoassay, were found in cell supernatants conditioned for 8 and 24 h. PDGF and bFGF markedly stimulated the release of M-CSF as early as 8 h, an effect persisting for at least 24 h. These findings suggest that liver FSC release M-CSF upon stimulation by PDGF and bFGF and may contribute to the activation of resident or infiltrating cells in inflammatory liver diseases.

The Florey Lecture, 1991. The colony-stimulating factors: discovery to clinical use

The four colony-stimulating factors, GM-GSF, G-CSF, M-CSF and Multi-CSF, are specific glycoproteins with a likely common ancestral origin which interact to regulate the production, maturation and function of granulocytes and monocyte-macrophages. Each has been purified and produced in active recombinant form. Animal studies have shown the ability of injected CSF to increase the production and functional activity of granulocytes and macrophages in vivo and to enhance resistance to infections. These studies have led to the current extensive clinical use of CSFs to promote the formation and function of granulocytes and macrophages in a wide variety of disease situations in which there is an associated risk of serious infections. Although our knowledge of the control of haemopoiesis remains incomplete, the approaches used to develop the CSFs can be used to extend this knowledge, with the promise of the introduction into clinical medicine of additional effective therapeutic agents.

Basic fibroblast growth factor (B-FGF) induces early- (CFU-s) and late-stage hematopoietic progenitor cell colony formation (CFU-gm, CFU-meg, and BFU-e) by synergizing with GM-CSF, Meg-CSF, and erythropoietin, and is a radioprotective agent in vitro

Basic fibroblastic growth factor (B-FGF) is a hormone-like protein which belongs to a class of heparin-binding growth factors. B-FGF is synthesized and released to circulate in the blood where it can be recognized by target cells through specific high-affinity plasma membrane receptors. B-FGF is known to be a potent mitogen for a number of specific cell types. We report data which demonstrates B-FGF can influence noncommited and specific lineage-derived hematopoietic progenitors when incubated in vitro. When combined with adherent cell-depleted normal murine marrow cells, B-FGF increased the number of both day 9 and day 12 spleen colony-forming units (CFU-s) from lethally irradiated animals. However, day 12-derived CFU-s were more sensitive to B-FGF, since optimal CFU-s production was observed at 10 ng/ml vs. 100 ng/ml for day 9 CFU-s (p less than 0.05). In adherent cell-depleted murine and human marrow cultures, the addition of B-FGF possessed synergistic activity in combination with the optimal concentration of GM-CSF for CFU-gm at a dose of 10 ng/ml which was inhibited in the presence of protamine sulfate (LD50 dose, 100 mu gm/ml), an inhibitor of B-FGF mitogenic activity, or in the presence of heparin (LD50 dose, 100 U/ml), an effective B-FGF binding agent. B-FGF also expressed synergistic activity in the presence of optimal concentrations of erythropoietin and Meg-CSF for murine and human BFU-e, and murine CFU-meg. No in vitro colony formation was observed when cells were cultured in the presence of B-FGF, but in the absence of the specific hematopoietic growth factor. Finally, B-FGF was also shown to be an effective radioprotective agent in vitro. Murine and human CFU-gm exposed to increasing doses of radiation (0.5 to 5 Gy) combined with GM-CSF and increasing doses of B-FGF (0.1 to 100 ng/ml) produced less radiation-induced toxicity compared to cultures containing GM-CSF alone. This data demonstrates B-FGF influences early- and late-stage hematopoietic progenitors, possesses synergistic activity with hematopoietic growth factors, and is a radioprotective agent in vitro. These results suggest B-FGF must be considered as a member of the family of molecules capable of influencing hematopoiesis in vitro.

Comparative distribution of marrow CFU-e and CFU-gm progenitors in different anatomic sites in the dog

The interpretation of marrow cloning activity, particularly in serial cultures, is greatly influenced by the reproducibility of the collected marrow samples. In order to establish whether bone marrow cloning activities and precision of the cloning assays are influenced by the site of bone marrow collection in the dog, we studied the incidence of marrow erythroid (CFU-e) and granulocyte-macrophage (CFU-gm) progenitor cells in the iliac crest, sternum, vertebrae, femur, and humerus, using microplasma clot and soft agar culture systems. Marrow samples obtained from the femur and humerus revealed consistently higher cell concentrations than those from the iliac crest, vertebrae, or sternum. Those aspirated from the sternum and vertebrae had lower cell concentrations and were less reproducible. Statistical analysis revealed no significant differences in the incidence of marrow CFU-e and CFU-gm progenitor cells between the femur, humerus, iliac crest or vertebrae. With multiple sampling, the marrow cloning efficiency was consistent and reproducible within the individual dogs. We conclude that the distribution of CFU-e and CFU-gm is comparable throughout the active marrow in the dog and that these sites may be used interchangeably for multiple quantitative analysis of marrow hematopoietic progenitor cells.

Gamma-irradiation response of cocultivated bone marrow stromal cell lines of differing intrinsic radiosensitivity

There is evidence for differences in the gamma-irradiation response of different cellular lineages within the bone marrow microenvironment. We previously reported that heterogeneity is demonstrable in the gamma-irradiation response of five clonal stromal cell lines, derived from one human bone marrow specimen, despite morphological, histochemical, cytogenetic, and functional similarity. In the present study we tested whether one stromal cell line could affect the intrinsic radiosensitivity of another. Two clonal stromal cell lines, which display distinct gamma-irradiation responses relative to dose rate were used: KM 101, which shows the same radiosensitivity at a low dose rate of 5 cGy/min (LDR) and a high dose rate of 120 cGy/min (HDR) and KM 104 which shows significant gamma-irradiation resistance at LDR. To facilitate the study of the gamma-irradiation response of each cell line during cocultivation, we derived stable subclones of each, expressing the transfected neomycin resistance (neo-r) gene, which confers resistance to the neomycin analog: G 418. Introduction of the neo-r gene did not alter cell lines radiosensitivity. The results show that cocultivation of stromal cell lines before, during, and after gamma-irradiation induces changes in repair of radiation-induced damage, with a dominant effect of a resistant cell line at LDR. In fact, the radiation survival curves of cocultivated stromal cell lines were always characteristic of KM 104, and a dose rate effect was observed, even when KM 101 was present in large excess. Moreover, our results are consistent with preferential killing of the more radiosensitive stromal cell line: both LDR and HDR Do values of the neo-r KM 101, cocultivated with the parent KM 104 for 24 hr before, and during gamma irradiation were significantly lower compared to the neo-r subclone irradiated alone. The LDR Do value of the neo-r KM 104 cocultivated for 24 hr before, and during gamma irradiation with excess of parent KM 101, was significantly higher, compared to the neo-r cells irradiated alone.

Effect of human macrophage colony-stimulating factor on granulopoiesis and survival in bone-marrow-transplanted mice

Human macrophage colony-stimulating factor (hM-CSF) has been isolated from normal human urine and purified to a homogeneous protein. The effect of hM-CSF on granulopoiesis was investigated in BALB/c mice transplanted with a suboptimal number of bone marrow cells. Lethally irradiated (7.8 Gy) mice were transplanted with 1 x 10(6) syngeneic mouse bone marrow cells and treated with a daily intraperitoneal dose of 64 micrograms/kg of hM-CSF for 5 days following the transplant. The hM-CSF injection resulted in stimulation of the recovery of blood neutrophils as well as an increase in the number of granulocyte-macrophage progenitor cells (CFU-GM) in the femur and spleen. The survival of lethally irradiated mice was dependent on the cell number transplanted; most mice transplanted with 2 x 10(4) cells died within 2 weeks. The recovery of hematopoiesis in mice transplanted with 2 x 10(4) cells was modestly but significantly stimulated by hM-CSF administration initiated from 5 days before or 1 day after transplantation for a 5-day period. Furthermore, the hM-CSF administrations markedly reduced the mortality in these mice during the early period after the transplantation. Since anaerobic bacteria were frequently detected in arterial blood immediately before the deaths but were not found in the surviving mice, it is speculated that early deaths occurring within 2 weeks after the transplant may be caused by opportunistic infections, and hM-CSF injection may prevent these mortal infections through its stimulating effect on monocyte-macrophage functions that are responsible for the production of hematopoietic regulators.

Sequential events in the pathogenesis of streptococcal cell wall-induced arthritis and their modulation by bis(5-amidino-2-benzimidazolyl)methane (BABIM)

This report builds on the authors' earlier discovery of bis(5-amidino-2-benzimidazolyl)methane (BABIM) as a strong suppressive agent for streptococcal cell wall fragment-induced arthritis in the Lewis rat. As a synthetic inhibitor of trypsinlike proteases, BABIM opens up a new route to the control of inflammatory joint disease. To gain a deeper insight into the function of the compound, the authors have now studied its influence on the sequential development of the joint changes and the associated lesions in spleen and liver. Bis(5-amidino-2-benzimidazolyl)methane is shown to block acute synovitis, to retard and reduce granuloma formation in spleen and liver, to decrease neutrophilic leukocytosis, and to diminish hemopoietic hyperplasia in the bone, and thus also to mitigate the distinctive osteoclastic and chondroclastic events. The compound does not interfere with the splenic immune response, the temporary rise in hepatocytic mitotic activity, or the organ deposition of streptococcal cell walls.

Preclinical and clinical evaluation of recombinant human macrophage colony-stimulating factor (rhM-CSF)

The promise of hematopoietic growth factors is now being realized as clinical trials become more mature. The uses of granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor are now becoming more established in therapeutic applications of disease states. A variety of new hematopoietic growth factors is on the horizon, including recombinant human macrophage colony-stimulating factor (rhM-CSF), which has recently entered clinical trials after extensive preclinical testing. The diverse biological actions of rhM-CSF will provide novel ways of approaching various medical problems across the disciplines of hematology, oncology, infectious disease and cardiology.

Interleukin-1, stromal cells, granulopoiesis, and the inflammatory response

A number of in vitro studies carried out in our laboratory over the past ten years have led to some clarification of the role of mononuclear phagocytes in hematopoietic regulation. The results of these studies have demonstrated that mononuclear phagocytes produce proteins, notably interleukin-1 (IL-1), that induce the expression of multilineage hematopoietic growth factors by human vascular endothelial cells, fibroblasts, T-lymphocytes, and thymic epithelial cells. More recently we and others have identified these induced factors as G-CSF, GM-CSF, IL-6, and IL-1. Although IL-1 seems to stimulate expression of these genes by inducing the accumulation of gene transcripts, interestingly the accumulation results from prolongation of mRNA half-life. We propose that the inductive capacity of IL-1 results from its activation of ribonuclease inhibitory activity in the cytoplasm of IL-1 induced cells and hypothesize that this may be a general mechanism by which IL-1 induces gene expression.

Recombinant tumor necrosis factor alpha and interleukin 1 alpha increase expression of c-abl protooncogene mRNA in cultured human marrow stromal cells

Analysis of protooncogene RNA expression in marrow stromal cells from long-term marrow culture demonstrated high levels of c-abl 5-, 6-, and 7-kilobase (kb) RNA transcripts. In experiments on three independently derived simian virus 40-transformed marrow stromal cell lines, the expression of these c-abl transcripts was further increased in response to recombinant tumor necrosis factor alpha (1000 units/ml) and interleukin 1 alpha (10 units/ml). Although lymphocyte-conditioned medium predominantly up-regulated the 5-kb transcript, interleukin 1 alpha primarily affected the 6-kb transcript. The up-regulation of the 5-kb c-abl message correlated with up-regulation of the granulocyte/macrophage colony-stimulating factor transcript and down-regulation of procollagen I transcripts in transformed cells. These data suggest that c-abl plays roles in the regulation of extracellular matrix expression and in the regulation of hematopoietic growth factors by stromal cells.

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.

Metabolism of phenol and hydroquinone to reactive products by macrophage peroxidase or purified prostaglandin H synthase

Macrophages, an important cell-type of the bone marrow stroma, are possible targets of benzene toxicity because they contain relatively large amounts of prostaglandin H synthase (PHS), which is capable of metabolizing phenolic compounds to reactive species. PHS also catalyzes the production of prostaglandins, negative regulators of myelopoiesis. Studies indicate that the phenolic metabolites of benzene are oxidized in bone marrow to reactive products via peroxidases. With respect to macrophages, PHS peroxidase is implicated, as in vivo benzene-induced myelotoxicity is prevented by low doses of nonsteroidal anti-inflammatory agents, drugs that inhibit PHS. Incubations of either 14C-phenol or 14C-hydroquinone with a lysate of macrophages collected from mouse peritoneum (greater than 95% macrophages), resulted in an irreversible binding to protein that was dependent upon H2O2, incubation time, and concentration of radiolabel. Production of protein-bound metabolites from phenol or hydroquinone was inhibited by the peroxidase inhibitor aminotriazole. Protein binding from 14C-phenol also was inhibited by 8 microM hydroquinone, whereas binding from 14C-hydroquinone was stimulated by 5 mM phenol. The nucleophile cysteine inhibited protein binding of both phenol and hydroquinone and increased the formation of radiolabeled water-soluble metabolites. Similar to the macrophage lysate, purified PHS also catalyzed the conversion of phenol to metabolites that bound to protein and DNA; this activation was both H2O2- and arachidonic acid-dependent. These results indicate a role for macrophage peroxidase, possibly PHS peroxidase, in the conversion of phenol and hydroquinone to reactive metabolites and suggest that the macrophage should be considered when assessing the hematopoietic toxicity of benzene.

Macrophage regulation of myelopoiesis is altered by exposure to the benzene metabolite hydroquinone

Hydroquinone, a myelotoxic metabolite of benzene, decreases the ability of murine bone marrow stromal cells to support myelopoiesis in vitro. Bone marrow stroma consists of macrophages and fibroblastoid stromal cells that participate coordinately in regulating myelopoiesis. The goal of this study was to determine if macrophage or fibroblastoid cell function is more sensitive to the myelotoxic actions of hydroquinone. To address this question, we developed purified populations of macrophages and fibroblastoid stromal cells and treated each population with hydroquinone. These cells were reconstituted together with nontreated cells of the opposite type and assayed for their ability to support the formation of granulocyte and macrophage colonies in an agar overlay. Reconstituted cultures containing hydroquinone-treated macrophages supported fewer colonies than did corresponding cultures containing untreated macrophages. Reconstituted cultures containing hydroquinone-treated fibroblastoid stromal cells were not affected. Moreover, hydroquinone reduced detectable interleukin-1 activity in purified macrophage cultures stimulated with lipopolysaccharide. These results indicate that hydroquinone selectively interferes with macrophage function possibly, in part, via alteration of macrophage interleukin-1 secretion.

Transcriptional and posttranscriptional modulation of myeloid colony-stimulating factor expression by tumor necrosis factor and other agents

Granulocyte (G) and granulocyte-macrophage (GM) colony-stimulating factors (CSF) are necessary for proliferation and differentiation of myeloid hematopoietic cells. Fibroblasts stimulated by tumor necrosis factor alpha (TNF alpha) and several other agents are a rich source of these CSF. The GM-CSF synthesized by these cells had the same molecular weight and glycosylation pattern as that produced by activated T lymphocytes, as shown by [35S]methionine labeling studies. Northern (RNA) blot analysis showed that the fibroblasts had trace levels of G- and GM-CSF mRNA. Both G- and GM-CSF mRNA concentrations coordinately increased after exposure of the cells to TNF alpha (greater than or equal to 5 ng/ml), 12-O-tetradecanoylphorbol 13-acetate (TPA) (greater than or equal to 5 x 10(-10) M), or cycloheximide (20 micrograms/ml). Both TNF alpha and TPA increased levels of G- and GM-CSF mRNA in the absence of new protein synthesis. Transcriptional run-on studies demonstrated that fibroblasts constitutively transcribed GM-CSF, and transcription was enhanced 3.0-fold by TNF alpha and 2.5-fold by TPA and was unchanged by cycloheximide. The stability of G- and GM-CSF transcripts was determined after exposure of the cells to actinomycin D; the half-lives of G- and GM-CSF mRNA in unstimulated cells were less than 0.25 h and were increased 2- to 16-fold in cells cultured with TNF, TPA, or cycloheximide. In summary, both transcriptional and posttranscriptional signals acted coordinately to modulate the levels of G- and GM-CSF mRNAs in fibroblasts.

Metabolic activation of hydroquinone by macrophage peroxidase

Lysates from macrophages, cells involved in hematopoiesis and immunological responses, catalyzed the metabolic activation of the benzene metabolite, hydroquinone, to protein-binding compounds and to free 1,4-benzoquinone. This reaction is mediated by a peroxidase since activation was dependent upon H2O2 and was prevented by the inhibitors aminotriazole and azide. Activation of hydroquinone was independent of HO. radicals since protein binding occurred in the presence of the HO. scavengers mannitol and dimethyl sulfoxide. In reactions with macrophage lysates, phenol, another hepatic metabolite of benzene, stimulated the production of 1,4-benzoquinone as well as the amount of hydroquinone equivalents bound to protein in a dose-dependent manner. Addition of cysteine to incubations with macrophage lysates resulted in a dose-dependent decrease in hydroquinone equivalents bound to protein. At 100 microM cysteine, protein binding was inhibited by 63% and this decrease was recovered as the monocysteine-hydroquinone conjugate. Macrophages catalyzed the arachidonic acid-mediated activation of hydroquinone to metabolites which bound to cellular macromolecules. This activation was inhibited by indomethacin indicating the action of prostaglandin synthase in hydroquinone metabolism by macrophages. The results of these experiments demonstrate that macrophage peroxidase catalyzes the metabolic oxidation of hydroquinone to 1,4-benzoquinone and that 1,4-benzoquinone and/or its semiquinone intermediate are binding to protein and cysteine. Hydroquinone activation by macrophages and subsequent macromolecular binding may be associated with the immunologic and hematopoietic toxicity of benzene.

Factors influencing release of granulocyte-macrophage colony-stimulating activity from human mononuclear phagocytes

Mononuclear phagocytes play an important role in the regulation of hematopoiesis, not only by producing regulatory monokines such as prostaglandins, tumor necrosis factor and interleukin-1 (IL-1), but also by the production of colony-stimulating activity (CSA). Previously, we have demonstrated that granulocyte-macrophage CSA (GM-CSA) production by mononuclear phagocytes can be induced by IL-1. In the present study, the influence of culture conditions on the production of GM-CSA was studied. It was found that both human sera and fetal bovine sera contain constituents - at present undefined - that induce GM-CSA production. These factors are distinct from IL-1 and lipopolysaccharide. In selected experiments, no GM-CSA-inducing effect of serum was found, suggesting that the effect may be donor-related. GM-CSA release in the presence of serum could be reduced by 40% after incubation of mononuclear phagocytes at low cell concentrations in methylcellulose, indicating that intimate cell-cell contact is an additional factor that enhances GM-CSA release.

Interleukin 1-dependent paracrine granulopoiesis in chronic granulocytic leukemia of the juvenile type

Marrow and peripheral blood cells from nine children with juvenile chronic granulocytic leukemia (JCGL) demonstrated intense (94 +/- 16% maximum) spontaneous granulocyte/macrophage colony growth but cells from five children with the adult variety of CGL did not. This unusual pattern of colony growth depended upon a stimulatory protein(s) produced by mononuclear phagocytes. No GM-CSA activity was found in any chromatofocused fraction of JCGL monocyte-conditioned media but an activity that induced GM-CSA in umbilical vein endothelial cells was detected at pI 6.9-7.2. Moreover, the CSA-inducing monokine was neutralized by an anti-IL-1 antibody in vitro and, in the one case so tested, the same antibody also inhibited "spontaneous" colony growth. Therefore granulocyte/macrophage colony growth in JCGL is characteristically abnormal and distinguishes JCGL from the adult form of the disease. This abnormality depends upon the production, by mononuclear phagocytes, of IL-1 which, in turn, stimulates the release of high levels of colony stimulating activity by other cells. The high proliferative activity of CFU-GM we found in JCGL patients, and the high levels of GM-CSA found in their serum are compatible with the view that the in vitro abnormality reflects a similar abnormality in vivo.

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.

Nerve growth factor promotes human hemopoietic colony growth and differentiation

Nerve growth factor (NGF) is a neurotropic polypeptide necessary for the survival and growth of some central neurons, as well as sensory afferent and sympathetic neurons. Much is now known of the structural and functional characteristics of NGF, whose gene has recently been cloned. Since it is synthesized in largest amounts by the male mouse submandibular gland, its role exclusively in nerve growth is questionable. NGF also causes histamine release from rat peritoneal mast cells in vitro, and we have shown elsewhere that it causes significant, dose-dependent, generalized mast cell proliferation in the rat in vivo when administered neonatally. Our experiments now indicate that NGF causes a significant stimulation of granulocyte colonies grown from human peripheral blood in standard hemopoietic methylcellulose assays. Further, NGF appears to act in a relatively selective fashion to induce the differentiation of eosinophils and basophils/mast cells. Depletion experiments show that the NGF effect may be T-cell dependent and that NGF augments the colony-stimulating effect of supernatants from the leukemic T-cell (Mo) line. The hemopoietic activity of NGF is blocked by polyclonal and monoclonal antibodies to NGF. We conclude that NGF may indirectly act as a local growth factor in tissues other than those of the nervous system by causing T cells to synthesize or secrete molecules with colony-stimulating activity. In view of the synthesis of NGF in tissue injury, the involvement of basophils/mast cells and eosinophils in allergic and other inflammatory processes, and the association of mast cells with fibrosis and tissue repair, we postulate that NGF plays an important biological role in a variety of repair processes.

Vascular endothelial cells and hematopoietic regulation

Vascular endothelial cells elaborate growth factors which support the proliferation and differentiation of hematopoietic progenitor cells. Both the regulation and potential biological significance of growth factor production by endothelial cells are reviewed.

Transcriptional and posttranscriptional modulation of myeloid colony-stimulating factor expression by tumor necrosis factor and other agents

Granulocyte (G) and granulocyte-macrophage (GM) colony-stimulating factors (CSF) are necessary for proliferation and differentiation of myeloid hematopoietic cells. Fibroblasts stimulated by tumor necrosis factor alpha (TNF alpha) and several other agents are a rich source of these CSF. The GM-CSF synthesized by these cells had the same molecular weight and glycosylation pattern as that produced by activated T lymphocytes, as shown by [35S]methionine labeling studies. Northern (RNA) blot analysis showed that the fibroblasts had trace levels of G- and GM-CSF mRNA. Both G- and GM-CSF mRNA concentrations coordinately increased after exposure of the cells to TNF alpha (greater than or equal to 5 ng/ml), 12-O-tetradecanoylphorbol 13-acetate (TPA) (greater than or equal to 5 x 10(-10) M), or cycloheximide (20 micrograms/ml). Both TNF alpha and TPA increased levels of G- and GM-CSF mRNA in the absence of new protein synthesis. Transcriptional run-on studies demonstrated that fibroblasts constitutively transcribed GM-CSF, and transcription was enhanced 3.0-fold by TNF alpha and 2.5-fold by TPA and was unchanged by cycloheximide. The stability of G- and GM-CSF transcripts was determined after exposure of the cells to actinomycin D; the half-lives of G- and GM-CSF mRNA in unstimulated cells were less than 0.25 h and were increased 2- to 16-fold in cells cultured with TNF, TPA, or cycloheximide. In summary, both transcriptional and posttranscriptional signals acted coordinately to modulate the levels of G- and GM-CSF mRNAs in fibroblasts.

Interleukin 1 stimulates T lymphocytes to produce granulocyte-monocyte colony-stimulating factor

T lymphocytes are thought to cooperatively interact with monocytes to produce colony-stimulating factors (CSF). However, little is known about monocyte-mediated signals leading to CSF-secretion by T lymphocytes, although soluble monocyte products have been implicated. We have employed monoclonal antibody anti-T3B covalently coupled to CnBr-activated Sepharose 4B beads, to show that multimeric ligation of T cell antigen receptor leads to T cell receptiveness to interleukin 1 (IL-1), as indicated by T cell production of CSF, which induces growth of myeloid progenitor cells into neutrophil, eosinophil, and monocyte colonies. To investigate the molecular basis of these findings, total RNA was extracted from T3B Sepharose-primed and IL-1-stimulated T lymphocytes and probed for granulocyte-monocyte-CSF (GM-CSF), granulocyte-CSF (G-CSF), and monocyte-CSF (M-CSF) mRNA. GM-CSF, but not G-CSF or M-CSF, messages were detected. Nuclear "run on" assays revealed that IL-1 action is effective primarily at the level of GM-CSF gene transcription. These results suggest a previously unrecognized role of IL-1 in the regulation of GM-CSF secretion by T cells.

Myelopoietic effect of bone marrow fibroblasts cultured from patients with myelofibrosis

Bone marrow fibroblasts (BMF) have been shown to be able to support granulopoiesis. The present studies were designed to see whether BMF in patients with agnogenic myeloid metaplasia (AMM) are also able to support granulopoiesis. Myeloid colony-stimulating activity (CSA) was assayed in BMF derived from the three groups of patients. 1) Group I: Patients with hip fracture but without underlying hematological disease; patients with solid tumor but without bone marrow metastasis; and patients with iron deficiency anemia. 2) Group II: Patients with myeloproliferative disorders other than AMM. 3) Group III: Patients with AMM or myelofibrosis with prior history of polycythemia vera. CSA was determined in a bilayer agar culture system in which BMF served as a feeder layer and either mouse or human marrow cells were employed as target cells. There was no difference of CSA production by BMF among these three patient groups. These studies suggest that BMF cultured from patients with myelofibrosis exhibit similar myeloid stimulating activity as do BMF from other patients. A significant correlation was also found between CSA production by BMF and white blood cell counts in patients with myelofibrosis (group III). This suggests that BMF may have a role in either supporting or producing CSA for granulopoiesis in myelofibrosis.

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.

Interleukin 1 stimulates fibroblasts to synthesize granulocyte-macrophage and granulocyte colony-stimulating factors. Mechanism for the hematopoietic response to inflammation

IL-1 is a family of polypeptides which play a critical role in the inflammatory response. Characteristics of this response include an enhanced release of bone marrow neutrophils, activation of circulating and tissue-phase phagocytes, and enhanced production of neutrophils and monocytes. We have sought to understand the hematopoietic response to acute and chronic inflammatory states on a cellular and molecular level. Colony-stimulating factors (CSFs) are glycoproteins involved in the production and activation of neutrophils and monocytes in vitro and in vivo. We have found that quiescent dermal fibroblasts constitutively release granulocyte-macrophage CSF (GM-CSF), granulocyte CSF (G-CSF), and macrophage CSF in culture, and that picomolar concentrations of the inflammatory mediator IL-1 stimulate by at least fivefold the transcription and release of GM-CSF and G-CSF. These findings establish the role of IL-1 in the hematopoietic response to inflammation through the stimulation of the production and release of GM-CSF and G-CSF.

Synergistic myelopoietic actions in vivo after administration to mice of combinations of purified natural murine colony-stimulating factor 1, recombinant murine interleukin 3, and recombinant murine granulocyte/macrophage colony-stimulating factor

Combinations of low dosages of purified murine hematopoietic colony-stimulating factors (CSFs)--L-cell CSF type 1 (CSF-1), recombinant interleukin 3 (IL-3), and recombinant granulocyte/macrophage CSF (GM-CSF)--were compared with single CSFs for their influence on the cycling rates and numbers of bone marrow granulocyte/macrophage, erythroid, and multipotential progenitor cells in vivo in mice pretreated with human lactoferrin. Lactoferrin was used to enhance detection of the stimulating effects of exogenously administered CSFs. Concentrations of CSFs that were not active in vivo when given alone were active when administered together with other types of CSF. The concentrations of CSF-1, IL-3, and GM-CSF needed to increase progenitor cell cycling rates were reduced by factors of 40-200, 10-50, and 40- greater than 400, respectively; the concentrations needed to increase progenitor cell numbers were reduced by factors of 40-500 (CSF-1), 20-80 (IL-3), and greater than 40- greater than 200 (GM-CSF) when these forms of CSFs were administered in combination with low dosages of one of the other forms of CSFs. The results demonstrate that different CSFs can synergize when administered in vivo to increase the cycling rates and numbers of marrow hematopoietic progenitor cells. These findings may be of relevance physiologically to the regulation of myeloid blood cell production by CSFs.

Comparative effects in vivo of recombinant murine interleukin 3, natural murine colony-stimulating factor-1, and recombinant murine granulocyte-macrophage colony-stimulating factor on myelopoiesis in mice

Purified murine colony-stimulating factors (CSF) recombinant interleukin 3 (IL-3), natural CSF-1, and recombinant granulocyte-macrophage (GM) CSF were assessed in vivo for their effects on BDF1 mouse bone marrow and spleen granulocyte-macrophage (CFU-GM), erythroid (BFU-E), and multipotential (CFU-GEMM) progenitor cells in untreated mice and in mice pretreated with purified iron-saturated human lactoferrin (LF). The CSF and LF preparations did not contain detectable endotoxin (less than 0.1 ng). Mice pretreated with LF were more sensitive to the effects of CSF. In mice pretreated with LF, 2,000 U IL-3 or 20,000 U CSF-1 significantly enhanced the cycling status and absolute numbers of all progenitors, whereas 20,000 U GM-CSF significantly increased the cycling status of CFU-GM and CFU-GEMM, but had no effect on cycling of BFU-E or on numbers of any of the progenitors. The effects of CSF in mice pretreated with LF were not mimicked by 0.1-100 ng E. coli lipopolysaccharide.

Haemopoietic reconstitution after allogeneic bone marrow transplantation in man: recovery of haemopoietic progenitors (CFU-Mix, BFU-E and CFU-GM)

Haemopoietic reconstitution was evaluated in 44 patients given HLA compatible sibling bone marrow transplants. The mean peripheral blood haemoglobin, neutrophil and platelet counts were markedly reduced early post-graft but returned to normal by 26 weeks post transplant. Bone marrow multipotent (CFU-Mix), erythroid (BFU-E) and myeloid (CFU-GM) progenitor cell reconstitution were also assessed at regular intervals up to 2 years post-graft. The mean value of CFU-GM increased gradually and attained a normal value by 52 weeks. The BFU-E value did not reach a normal value until after 52 weeks post-graft. However, CFU-Mix growth appeared to be impaired even up to 2 years post-transplant. The occurrence of graft versus host disease at 3 months post-transplant was associated with significantly lower mean numbers of platelets, marrow CFU-GM, BFU-E and CFU-Mix. Post-transplant patients who were on methotrexate therapy were also shown to have lower marrow CFU-GM and neutrophil values compared to those patients who received cyclosporin post-transplant. This study demonstrated that although peripheral blood counts were normal after 26 weeks post-graft, marrow stem cell reserve in these patients was reduced. This might in part explain the documented increase in risk of severe infections or thrombocytopenia in some of these patients, particularly during viral infection, graft-versus-host disease or immunosuppressive treatment.

Interleukin 1 induces cultured human endothelial cell production of granulocyte-macrophage colony-stimulating factor

Monokine-stimulated endothelial cells are known to produce both burst- and colony-stimulating activities, but neither the nature of the monokine nor the hematopoietic growth factor(s) produced is known. We show by mRNA analysis that an immortalized line of human endothelial cells constitutively produce granulocyte-macrophage colony-stimulating factor. Furthermore, interleukin 1 and tumor necrosis factor induce early passage human umbilical endothelial cells to produce the same growth factor.

Approaches to ablating the myelotoxicity of chemotherapy

Myelotoxicity remains a significant dose-limiting side effect of chemotherapy contributing to the morbidity and mortality of patients undergoing treatment for cancer. A number of different experimental approaches are being studied, both in the clinic and in the laboratory, in an attempt to prevent this iatrogenic complication. The present review provides a synopsis of the various myeloprotective strategies now being employed in experimental trials. Emphasis is placed on the use of putative physiologic bioregulatory molecules (lactoferrin, prostaglandin E, interferon) to prevent or lessen chemotherapy-induced myelotoxicity, with consideration also given to other promising treatment modalities (i.e., adenosine, lithium, diethyldithiocarbanate).

Interleukin 1 stimulates granulocyte macrophage colony-stimulating activity release by vascular endothelial cells

Studies designed to characterize monocyte-derived recruiting activity (MRA) a monokine that stimulates endothelial cells to produce granulocyte macrophage-colony-stimulating activity (CSA) by endothelial cells, show that it is a thermolabile protein of from 12,000 to 24,000 D which, on chromatofocusing, shows three separate peaks of eluted activity from pH 7.5 to 5.0. Because these and many other properties of MRA are identical to those of interleukin 1 (IL-1), we tested the hypothesis that MRA and IL-1 are identical. We cultured vascular endothelial cells with various concentrations of purified native and recombinant IL-1 (pI 7 form), then tested the endothelial cell supernatants for GM-CSA. Purified native IL-1 and recombinant IL-1 stimulated endothelial cells to release CSA. The MRA of native IL-1, recombinant IL-1, and unfractionated monocyte conditioned medium was neutralized by a highly specific rabbit anti-human IL-1 antiserum. Chromatofocusing fractions that contained MRA contained immunoreactive IL-1 on immunoblotting and the bioactivity was neutralized completely by treatment with the antiserum. We conclude that IL-1 induces the release of CSA by vascular endothelial cells, that IL-1 is constitutively produced by monocytes in vitro, and that MRA and IL-1 are biologically, biophysically and, immunologically identical.

Biomolecule-cell interactions and the regulation of myelopoiesis

The regulation of myelopoiesis in vivo most likely entails a complex set of interactions between cell-derived biomolecules and their target cells. Much of what we currently know of these interactions has been derived from studies in vitro utilizing techniques for the purification of both the biomolecules and the cells producing and responding to these factors. Stimulating and suppressing influences have been uncovered, and with the cloning and purification of biologically active factors, studies assessing the actions of these molecules in vivo have begun. From studies in vitro it is apparent that many of the purified molecules can have move than one action and that different molecules can collaborate in a synergistic manner to enhance or suppress functional endpoints.