Control of granulocytes and macrophages: molecular, cellular, and clinical aspects

Immunomodulation of peritoneal macrophages by granulocyte-macrophage colony-stimulating factor in humans

Colony-stimulating factors are growth factors which induce differentiation of the hematopoietic stem cells. Granulocyte-macrophage colony-stimulating factor (GM-CSF) stimulates proliferation and improves functions of neutrophils and monocyte/macrophages. A macrophage submesothelial stratum has been suggested to constitute the first line of peritoneal defense. We have tested whether intraperitoneally administered GM-CSF could increase the number and activation of peritoneal macrophages in peritoneal dialysis patients. Eight stable patients injected 17 micrograms of GM-CSF in each of their four daily CAPD bags over three days. The clinical status, the peritoneal effluent and peripheral blood cell count, membrane receptor expression, phagocytosis activity and cytokine levels were monitored at days 0, 1, 3, 10 and 28. GM-CSF administration caused a large increase in peritoneal macrophage number (89-fold mean increase after 72 hr), returning to baseline seven days after withdrawal. GM-CSF triggered an increase in the expression of CD11b/CD18 (CR3) and its counterreceptor CD54, indicating the cellular progression into a more activated state. Both the number of phagocytic cells (55 +/- 15% to 83 +/- 10%, P < 0.05) and the phagocytic index (137 +/- 29 to 255 +/- 61, P < 0.01) were also augmented. Peritoneal effluent cytokine-chemokine levels demonstrated an increase in IL-6 and MCP-1 levels while TNF-alpha, IL-1, IL-8, MIP-1 alpha and RANTES were not significantly altered. GM-CSF administration did not affect the peritoneal transport of water or solutes. Minor side-effects were registered in two patients. In conclusion, intraperitoneal GM-CSF causes a marked and transient recruitment of primed macrophages into the peritoneum without inducing inflammatory parameters. GM-CSF should improve the peritoneal defensive capacity through potentiation of the effector functions of resident and newly-recruited macrophages.

Kinetics of continuous GM-CSF production by recombinant Saccharomyces cerevisiae in an airlift bioreactor

Continuous production of murine GM-CSF by recombinant Saccharomyces cerevisiae in an airlift bioreactor was studied at three different dilution rates. The reactor was initially fed with a selective medium to increase cell concentration, and then was fed with a rich, nonselective medium for GM-CSF production. Ethanol was used as the main carbon source to provoke GM-CSF expression. In continuous culture, GM-CSF production was maintained for over 150 h, even though the fraction of plasmid-carrying cells continuously dropped to lower than 20%. The stable GM-CSF production during the later phase of the continuous culture was attributed to increased specific cell productivity possibly resulting from an increase in the plasmid copy number in plasmid-carrying cells. This also indicated the possibility of natural selection of high-copy number cells in continuous culture. Plasmid stability was found to be growth rate (dilution rate) dependent; it increased with the dilution rate. Reactor productivity and specific productivity also increased with the dilution rate. A two-parameter kinetic equation was used to model the plasmid stability kinetics. The growth rate ratio between plasmid-carrying and plasmid-free cells increased from 0.996 to 0.998 while the segregational instability or the probability of plasmid loss from each cell division increased from 1.1% to 16% as the dilution rate decreased from 0.11 h-1 to 0.05 h-1. Oscillation of the dilution rate between 0.05 h-1 and 0.11 h-1 stabilized the plasmids and gave a higher productivity than that achieved without oscillation.

Stem cell factor and stromal cell co-culture prevent apoptosis in a subculture of the megakaryoblastic cell line, UT-7

The megakaryoblastic cell line, UT-7, is dependent for its growth upon interleukin-3 (IL-3), erythropoietin, or granulocyte-macrophage colony stimulating factor (GM-CSF). A subculture of this line can be maintained in recombinant human c-kit ligand [stem cell factor (SCF)] at 100 ng/ml without requirement for other growth factors. Removal of this subculture from SCF results in rapid loss of viability and decreased proliferation. Cells grown in SCF also can be maintained in GM-CSF but not vice versa. In this work, we have characterized the SCF dependence of this UT-7 subculture. Stem cell factor removal results in apoptosis and a decline in viability which can be restored partially by re-addition of SCF, GM-CSF, or co-culture with adherent marrow stromal cells. Apoptosis in the factor-starved UT-7 population has been documented by light microscopy, electron microscopy and DNA analysis, showing the typical 180 base pair laddering characteristic of apoptosis. To quantitate the degree of apoptosis in the cell populations, and to assess whether apoptosis decreased with re-exposure of starved cells to growth factors or stroma, we utilized flow cytometry. This confirmed that exposure of previously factor-starved cells to stroma decreased the percentage of cells undergoing apoptosis. Co-culture with an SCF-deficient murine stromal cell line was also able to prevent apoptosis, suggesting contribution of other stromal cell factors. Experiments performed using trans-well inserts which do not allow cell passage, showed greatest viability of cells in contact with stroma, but viability was also improved in cells cultured in the presence of, but not in contact with, stromal cells compared to those cultured above plastic, suggesting a role for soluble stroma-produced substances. These data demonstrate that SCF alone can prevent apoptosis in cells dependent upon its presence for proliferation. Also, marrow stromal cells can serve as a partial substitute for growth factor in the prevention of apoptosis in these cells, probably due to constitutive presentation of SCF and other hematopoietic growth factors in both soluble and surface-bound forms.

T cell interleukin-17 induces stromal cells to produce proinflammatory and hematopoietic cytokines

Analysis of the cDNA encoding murine interleukin (IL) 17 (cytotoxic T lymphocyte associated antigen 8) predicted a secreted protein sharing 57% amino acid identity with the protein predicted from ORF13, an open reading frame of Herpesvirus saimiri. Here we report on the cloning of human IL-17 (hIL-17), the human counterpart of murine IL-17. hIL-17 is a glycoprotein of 155 amino acids secreted as an homodimer by activated memory CD4+ T cells. Although devoid of direct effects on cells of hematopoietic origin, hIL-17 and the product of its viral counterpart, ORF13, stimulate epithelial, endothelial, and fibroblastic cells to secrete cytokines such as IL-6, IL-8, and granulocyte-colony-stimulating factor, as well as prostaglandin E2. Furthermore, when cultured in the presence of hIL-17, fibroblasts could sustain the proliferation of CD34+ hematopoietic progenitors and their preferential maturation into neutrophils. These observations suggest that hIL-17 may constitute (a) an early initiator of the T cell-dependent inflammmatory reaction; and (b) an element of the cytokine network that bridges the immune system to hematopoiesis.

In vitro characterization of a novel avian haemopoietic growth factor derived from stromal cells

To better define the role of the chicken haemopoietic microenvironment in supporting haemopoiesis, a continuous cell line was generated by RSV transformation of avian spleen stromal cells (SSL-1). Supernatants from this line were found to contain haemopoietic growth factor activity as measured by the ability to induce proliferation and differentiation of precursor cells present in embryonic and post-hatched haemopoietic tissues. Comparison of cultures grown in the presence of cMGF and SSL-1 conditioned media (CM) revealed that both cytokine sources induced similar types of cell populations. Both sources supported the proliferation of predominantly macrophage-like cells based on colony morphology, differential staining, non-specific esterase staining, and phagocytosis activity. Interestingly, SSL-1 does not express any message for cMGF, nor does it secrete any IL-2 or interferon activities suggesting that the growth factor activities seen in SSL-1 are novel.

Binding of human GM-CSF to synthetic peptides of the alpha subunit of its receptor

We have synthesized a series of peptides corresponding to portions of the extracellular domain of human granulocyte-macrophage colony stimulating factor receptor alpha subunit (hGM-CSFR alpha). The sequences were chosen according to the homology between hGM-CSFR alpha and the growth hormone receptor (GHR) and correspond to the regions reported to form the binding site of the latter receptor. The peptides were examined for their binding activity to hGM-CSF by affinity chromatography on resin-immobilized hGM-CSF and by a solid phase binding assay. For peptides endowed with hGM-CSF binding activity were identified and the postulated homology between the binding sites of hGM-CSFR alpha GHR was confirmed.

Avian hematopoiesis in response to avian cytokines

The objective of this study was to examine the hematopoietic cell proliferation and differentiation potential of growth factors produced by chicken macrophages. Bone marrow (BM) cells (25 x 10(3)) from newly hatched B15B15 K-strain Leghorn chicks were seeded in .5 mL serum-free semi-solid culture supplemented with 10% (vol/vol) of a conditioned medium (CM) from a chicken macrophage cell line, MQ-NCSU. The conditioned medium was obtained by culturing MQ-NCSU cells either in LM-HAHN (CMI) or RPMI-1640 (CMII) growth medium. The control cultures contained only LM-HAHN or RPMI medium. Bone marrow cells in the presence of CMI differentiated predominately into granulocyte colonies (Experiment 1 = 84 +/- 9.2; Experiment 2 = 105 +/- 5). No colonies were observed in the control cultures. Stimulation of MQ-NCSU cells with lipopolysaccharide (LPS) produced a CM that differentiated BM cells predominantly into macrophage colonies (122 +/- 16.3 in CMI and 92 +/- 5.6 in CMII). These data suggest that MQ-NCSU cells spontaneously secrete a factor with the potential to promote granulocyte differentiation. However, upon stimulation with LPS, the factor secreted had macrophage colony stimulation potential (M-CSF), which was similar in activity when compared with the activity of recombinant chicken myelomonocytic growth factor (r-cMGF). Another CM from chicken fibroblasts (FCM) was tested on BM cells from K-strain Leghorns and Arbor Acres x Arbor Acres broiler chicks. Data from three experiments showed that 25 x 10(3) BM cells from K-strain chicken yielded more macrophage and granulocytes colonies (82 +/- 14) than those from broilers (56 +/- 12). This study suggests that avian cytokines exhibit progenitor cell differentiation potential and that this activity is dependent upon the source of cytokines and their targets.

Efficacy of delayed granulocyte colony-stimulating factor after full dose CHOP therapy in non-Hodgkin's lymphoma: a pilot study for a leukocyte count oriented regimen

Bone marrow toxicity is a great challenge for physicians treating patients with non-Hodgkin's lymphoma (NHL) and prescribed chemotherapy. Granulocyte colony-stimulating factor (G-CSF) prevents myelotoxicity, but the optimal timing and scheduling of G-CSF administration has not been ascertained. We investigated leukocyte count oriented G-CSF administration schedules, as related to full dose administration of cyclophosphamide, adriamycin, vincristine, and prednisolone (CHOP) chemotherapy, with shortened intervals. Thirty-eight Japanese patients with NHL were included in this study. The standard CHOP combination was administered in six cycles. Patients were given G-CSF in a dose of 2 micrograms/kg/day, subcutaneously starting the day when total leukocytes were < 3,000/microliters. When leukocyte count remained at > 3,000/microliters, G-CSF was started 10 days following CHOP. Treatment with G-CSF was discontinued after the leucocyte count reached > 10,000/microliters, and CHOP was started the next day (CHOP-G treatment; CHOP-G). Doses were not modified in any patient. Patients over 70 years of age received 2/3 of the standard dosage. In the first cycle of CHOP, the day of initiation of G-CSF was 9.6 days following CHOP in the first cycle and 7.7 to 8.5 days during 2 to 6 cycles. The mean duration of G-CSF injection was 7.4 days with a range from 6.8 to 8.0 days, in each CHOP cycle. The mean intervals of CHOP-G was 14.7 days during six consecutive courses, and there was no prolongation of the intervals, even in later cycles. In 23 patients who received all six cycles of CHOP-G, the overall response rate was 91.3% (73.9% complete remission; CR and 17.4% partial remission; PR). In 32 patients with intermediate grade NHL, the overall response rate was 84.4% (65.5% CR and 18.8% PR). Thus, the full dose CHOP with G-CSF, based on the leukocyte count oriented schedule, can be achieved with shortened intervals, an approach which will increase the quality of life (QOL) for the patients by reducing the days of treatment as well as the cost of G-CSF.

Differential alterations in plasma colony-stimulating factor concentrations in meningococcaemia

To determine whether circulating levels of any of the colony-stimulating factors (CSF) might contribute to the host response in severe sepsis, plasma concentrations of granulocyte CSF (G-CSF), granulocyte-macrophage CSF (GM-CSF), and macrophage CSF (M-CSF) were measured by immunoassays in 20 subjects with meningococcaemia, a bloodstream infection caused by Neisseria meningitidis, that has proven to be a valuable model to study the responses of other inflammatory mediators during sepsis and septic shock in humans. Plasma G-CSF concentrations were transiently elevated in most subjects during the early phase of meningococcaemia, and were higher in subjects with septic shock (mean +/- s.d. = 165 +/- 142 ng/ml, n = 9) compared with those who remained normotensive (mean +/- s.d. = 7 +/- 2 ng/ml, n = 10) (P < 0.05). Peak plasma G-CSF concentrations > 10 ng/ml were associated with the development of septic shock (P < 0.01), disseminated intravascular coagulation (P < 0.01), fulminant infection (P < 0.05), and a fatal outcome (P < 0.01). Plasma GM-CSF concentrations > 1 ng/ml were briefly present in subjects with life-threatening septic shock (1-15 ng/ml, n = 5), and were strongly associated with fulminant meningococcaemia (P < 0.01). Plasma M-CSF concentrations were marginally elevated in all subjects, but were not associated with complications related to or arising from sepsis-induced organ injury. This study demonstrates that plasma levels of G-CSF, GM-CSF and M-CSF show very different responses during meningococcaemia, changes which presumably reflect the different roles played by these mediators in sepsis and, potentially, in septic shock.

Erythroid development of the FDCP-Mix A4 multipotent cell line is governed by the relative concentrations of erythropoietin and interleukin 3

Conditions are described which promote the erythroid development of the FDCP-Mix A4 (A4) cell line with accompanying proliferation of the cells. The requirements for this development are low concentrations of interleukin 3 (IL-3) plus the presence of erythropoietin (epo) and haemin. When high concentrations of IL-3 are added with erythropoietin and haemin the cells do not differentiate and maintain their blast cell morphology. Addition of haemin, in the absence of erythropoietin, does not promote erythroid development, but the presence of haemin with erythropoietin promotes increased proliferation and maturation. The morphological maturation of A4 cells along the erythroid lineage is accompanied by a gradual loss of clonogenic potential, loss of A4 cell multipotency, increased erythropoietin receptor expression, and an increased expression of the beta-globin gene. An initial increase in mitogenic responsiveness to erythropoietin is followed by a decrease as the cells become refractory to all mitogenic stimuli with the acquisition of a postmitotic, mature erythroid cell phenotype.

Hematopoietic stem cell cytokine response

The process of hematopoiesis can be modelled on the concept of a pluripotential stem cell able to differentiate and proliferate in multiple lineages. This process proceeds under the permissive or directive influence of "early" and "late" acting hematopoietic cytokines probably acting in synergistic combinations within the context of the marrow stromal microenvironment. Further characterization of the biochemical events that transduce cytokine signalling into cellular events and the ultimate description of the earliest progenitor cell populations and the cytokines which influence them will provide key insights into embryogenesis and tissue maintenance as well as suggest new therapeutic approaches for hematologic and malignant diseases.

Optimal timing of granulocyte colony-stimulating factor (G-CSF) administration after bone marrow transplantation. A prospective randomized study

The positive role of G-CSF in hastening the myeloid recovery of patients undergoing allogeneic bone marrow transplantation (ALLO-BMT) or autologous bone marrow transplantation (ABMT) has recently been established. Considerable knowledge about adequate doses and route of administration has been accumulated in the past few years. Nonetheless, the optimal time to start growth-factor administration remains undetermined. We have performed a stratified study according to the source of hematopoietic progenitors (ALLO-BMT or ABMT), underlying disease and its stage, and acute graft-versus-host disease (GVHD) prophylaxis regimen and randomized patients in two arms: group A, which started G-CSF on day 0 (36 patients), and group B, which started on day +7 post-BMT (39 patients). The same dose (5 micrograms/kg/day) and route of administration were employed in both groups. We found no significant differences in the time to reach an absolute neutrophil count (ANC) of 0.1, 0.5, and 1 x 10(9)/l and 50 x 10(9) platelets/l (medians: 10 and 11, 14.5 and 14, 17 and 16, 23 and 24 days, respectively, in groups A and B). We did not find differences in the days of fever or days on antibiotic treatment with less than 1 x 10(9)/l ANC, rate of bacteriemia, or days of hospitalization in both groups. In contrast, a considerable saving of G-CSF in B group was found (mean days of infusion in group A, 18, versus 11 in group B) (p < 0.0001). This is equivalent to a saving of 1120 $US per patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Synergistic action of two sources of avian growth factors on proliferative differentiation of chick embryonic hematopoietic cells

During embryonic development, the components of the avian immune system undergo ontogeny in several distinct organs, including the bone marrow, spleen, thymus, and bursa of Fabricius. This process is regulated and controlled by the complex interactions of various cytokines and colony-stimulating factors (CSF). The objective was to examine the action of two different sources of hematopoietic growth factors, spleen-conditioned media (SCM) and chick embryo extract (CEE), on the proliferation of hematopoietic cells from various organs and on the differentiation of progenitor cells in semi-solid culture. Spleen and bone marrow cells obtained at Day 16 of incubation responded in a dose-dependent manner to the addition of SCM and CEE alone or in combination. No proliferative effect of SCM was observed on cells obtained from embryonic thymus or bursa. Clonal analysis of bone marrow and spleen cells suggested that CEE may contain the avian equivalents of stem cell factor, interleukin-3, granulocyte-macrophage CSF, granulocyte-CSF, and macrophage-CSF. Clonal analysis of SCM cultures suggested that in addition to myelomonocytic growth factor, which affects primarily macrophage-granulocyte lineages, a thrombocyte-CSF-like activity was also apparent. The SCM alone tended to act upon committed late progenitors. The combination of CEE and SCM amplified the size and the total number of colonies obtained and appeared to act synergistically upon progenitors with a high level of proliferative potential. This response on young progenitors was confirmed when cells were cultured in CEE and SCM prior to clonal analysis. These results document the presence of thrombocyte CSF in SCM and the effect of both CEE and SCM on the proliferative differentiation of avian embryonic hematopoietic progenitors.

Antibodies to canine granulocyte colony-stimulating factor induce persistent neutropenia

A severe persistent neutropenia developed in a rabbit that was injected intradermally with 120, 60, 60, and 120 micrograms of recombinant canine granulocyte colony-stimulating factor (cG-CSF) on days 1, 22, 31, and 44, respectively. The neutropenia was present from day 44 to day 205. The nadir of the neutropenia (60 cells/microliters) occurred in conjunction with peak antibody titer (640,000) to cG-CSF on day 58. The immune antiserum from this rabbit reacted positively for cG-CSF on Western blot analysis. The immune antiserum also neutralized the activity of cG-CSF. On day 160, examination of the bone marrow showed marked granulocytic hypoplasia and mild erythroid hyperplasia. On day 205, the rabbit was still neutropenic (430 cells/microliters), even though the last injection of cG-CSF was given 161 previously. Necropsy on day 205 showed that there was still mild granulocytic hypoplasia with mild erythroid hyperplasia. Because of the lack of any inflammatory foci found at necropsy and the granulocytic hypoplasia, it was thought that the neutropenia was most likely due to decreased production and was not a consumptive process. It is hypothesized that the antibody that was produced to cG-CSF neutralized the effect of endogenous rabbit granulocyte colony-stimulating factor and prevented the normal proliferation and maturation of the rabbit neutrophils.

Carboxypeptidase M is identical to the MAX.1 antigen and its expression is associated with monocyte to macrophage differentiation

The two monoclonal antibodies MAX.1 and MAX.11 recognize cell surface antigens that are almost undetectable on monocytes but highly expressed on differentiated macrophages. Biochemical characterization revealed that both antibodies detect the same 58-64-kDa glycoprotein anchored to the plasma membrane by glycosyl-phosphatidylinositol linkage. We purified the MAX.1/11 antigen by immunoaffinity chromatography using monoclonal antibody MAX.11. The NH2-terminal amino acid sequence was determined and turned out to be identical to the NH2-terminal sequence of the membrane-bound carboxypeptidase M. By precipitation with antibodies MAX.1 and MAX.11, membrane preparations of macrophages and placental microvilli were almost completely depleted of enzyme activity, indicating that the two antibodies indeed recognize carboxypeptidase M. Immunoreactivity of both antibodies correlates with the reported tissue distribution of enzyme activity. Expression of carboxypeptidase M on mRNA level and enzymatic activity markedly increase during in vitro differentiation of monocytes, according to the described increase in MAX.1 and MAX.11 antigen expression. Moreover, in vitro differentiated macrophages show the highest specific activity yet described in any tissue. In addition, carboxypeptidase M expression could be detected in HL-60, U937, and THP-1 myeloid cell lines. Vitamin D3-induced monocytic differentiation resulted in an increased carboxypeptidase M expression in all three cell lines. Further studies are needed to elucidate the functional role of carboxypeptidase M during monocytic differentiation and activation.

Autonomous proliferation of neural precursors in the tadpole retina revealed after partial removal of the embryonic eyebud

The cellular mechanisms that regulate cell division in the developing vertebrate nervous system are essentially unknown. Using the frog retina as a model system, we tested the hypothesis that proliferation is regulated by feedback signals that encode the total number of cells in the population. To alter the number of cells in the retina, we surgically removed approximately half of the embryonic eyebud. In a previous study, cell counts made immediately after partial ablation showed that the number of proliferating, undifferentiated cells was reduced to 70% of the number in the contralateral control eye, while the number of postmitotic, differentiated cells was reduced to 47%. In this study, we sought to determine whether these reduced cell number of affected proliferation, which was assessed by counting the total number of cells present at various times after surgery. The partially ablated retinas consistently had fewer cells than the contralateral retinas. Analyses of the cell numbers suggested that there was little or no change in mitotic rate in the partially ablated retinas and that the decreased production of both differentiated and undifferentiated cells was due almost entirely to the reduction in the number of dividing cells. There is thus no evidence that retinal stem cells up-regulate their production of new cells in response to a reduction of either the stem cells themselves or of their descendants. This lack of response to population size indicates that, in contrast to many non-neural stem cell systems, proliferation of neural stem cells is not regulated by a feedback mechanism but instead is largely autonomous.

CSF-1 and mouse preimplantation development in vitro

The effects of macrophage colony stimulating factor on the development of the zygote to the blastocyst stage of an outbred strain of mouse have been studied in KSOM, an improved medium that supports a high rate of in vitro development. Macrophage colony stimulating factor accelerates the formation of the blastocyst cavity by day 4 (96 hours post-hCG). It also increases overall embryonic cell number through a differential increase in the number of trophoblast cells, with no significant effect on the number of inner cell mass cells. By day 5 of culture (120 hours post-hCG), colony stimulating factor-treated embryos have about 20 more trophoblast cells than control embryos, an increase of about 30 percent of the total number of cells in a control blastocyst. The maximum response of embryos was obtained at a concentration around 540 U ml-1 colony stimulating factor (identical to 918 Stanley units ml-1), and the cytokine can produce the same effects even if it is present in the medium for only part of the culture period. This in vitro stimulation of preimplantation development with macrophage colony stimulating factor is compatible with continued normal fetal development in vivo.

Potent interleukin 3 receptor agonist with selectively enhanced hematopoietic activity relative to recombinant human interleukin 3

A systematic evaluation of structure-activity information led to the construction of genetically engineered interleukin 3 (IL-3) receptor agonists (synthokines) with enhanced hematopoietic potency. SC-55494, the most extensively characterized member of this series, exhibits 10- to 20-fold greater biological activity than recombinant human IL-3 (rhIL-3) in human hematopoietic cell proliferation and marrow colony-forming-unit assays. In contrast, SC-55494 is only twice as active as rhIL-3 in priming the synthesis of inflammatory mediators such as leukotriene C4 and triggering the release of histamine from peripheral blood leukocytes. The enhanced hematopoietic activity of SC-55494 correlates with a 60-fold increase in IL-3 alpha-subunit binding affinity and a 20-fold greater affinity for binding to alpha/beta receptor complexes on intact cells relative to rhIL-3. SC-55494 demonstrates a 5- to 10-fold enhanced hematopoietic response relative to its ability to activate the priming and release of inflammatory mediators. Therefore, SC-55494 may ameliorate the myeloablation of cancer therapeutic regimens while minimizing dose-limiting inflammatory side effects.

Evidence for an important role of IGF-I and IGF-II for the early development of chick sympathetic neurons

The ability of immature neurons from chick lumbosacral sympathetic ganglia to proliferate in vitro was used to identify factors that affect neurogenesis. Under serum-free culture conditions, insulin-like growth factor I (IGF-I), IGF-II, or insulin caused an increase in the proportion of cells that incorporated [3H]thymidine. In addition, IGFs also stimulated neurite outgrowth from these immature sympathetic neurons. IGF-I and IGF-II mRNA was found to be expressed in E7 sympathetic ganglia during the period of neurogenesis. IGF-I was detectable in fibroblasts, whereas IGF-II mRNA was expressed by neurons, glia, and fibroblasts. Elimination of endogenous IGFs by neutralizing antibodies resulted in a reduction of neuron proliferation and neuron number, whereas elevation of IGF levels by treatment with IGF-I increased sympathetic neuron proliferation in vivo. These findings suggest an important role of IGFs for the development of sympathetic neurons and imply a general role of IGFs in the control of neurogenesis and neurite outgrowth.

Phosphorylation of a Fes-related protein in response to granulocyte-macrophage colony stimulating factor

Previous work has suggested that a 97-kDa protein (p97) is involved in the signal transduction pathway of granulocyte-macrophage colony stimulating factor (GM-CSF) as well as interleukin 3, erythropoietin, and interleukin 2. We have examined the relationship of p97 to the protein tyrosine kinase Fes in the GM-CSF signal transduction pathway in erythroid and myeloid cell lines. GM-CSF stimulation of three different cell lines induced tyrosine phosphorylation of p97 as well as a number of other phosphotyrosylproteins. Although each cell line expressed the proto-oncogene product Fes, antisera specific for Fes did not recognize p97 in immunoblotting experiments. Furthermore, immunodepletion of Fes did not reduce the amount of p97 in GM-CSF-treated cells. Two-dimensional gel electrophoresis demonstrated that p97 and Fes have similar charge to mass ratios, and limited proteolytic mapping of p97 and Fes suggested that these proteins may be related but are not identical. Our studies demonstrate that p97 is not Fes but is probably a Fes-related protein.

Mice deficient for the IL-3/GM-CSF/IL-5 beta c receptor exhibit lung pathology and impaired immune response, while beta IL3 receptor-deficient mice are normal

The receptors for IL-3, GM-CSF, and IL-5 share a common beta subunit (beta c), and mice have an additional IL-3 beta subunit (beta IL3). We have independently generated mice carrying null mutations of each molecule. beta c mutant bone marrow showed no response to GM-CSF or IL-5, whereas IL-3 stimulation of beta c or beta IL3 mutant bone marrow was normal. beta c mutant mice showed lung pathology consisting of lymphocytic infiltration and areas resembling alveolar proteinosis, and also exhibited low basal numbers of eosinophils. Infection of beta c mutant mice by Nippostrongylus brasiliensis resulted in the absence of blood and lung eosinophilia. Animals repopulated with beta c mutant bone marrow cells showed slower leukocyte recovery and reduced eosinophil numbers. These data define the role of beta c in vivo, and show a phenotype that is likely to be the cumulative effect of loss of GM-CSF and IL-5 stimulation.

Induction of tumour necrosis factor-alpha by single and repeated doses of the antitumour agent 5,6-dimethylxanthenone-4-acetic acid

5,6-Dimethylxanthenone-4-acetic acid (DMXAA), a low-molecular-weight biological response modifier scheduled for clinical evaluation, induced synthesis of tumour necrosis factor-alpha (TNF-alpha) in serum of mice, with maximal activity being observed at 2-3 h after administration. At a dose of 27.5 mg/kg, DMXAA induced similar TNF-alpha concentrations as did flavone-8-acetic acid given at its maximum tolerated dose (MTD; 330 mg/kg), whereas 8-methylxanthenone-4-acetic acid, which has no antitumour activity, did not induce serum TNF-alpha at its MTD (440 mg/kg). The dependence of schedule on TNF-alpha induction was studied by giving DMXAA to mice in two doses of 27.5 mg/kg each separated by different intervals. An interval of 0 (i.e. 55 mg/kg given in a single dose) produced a TNF-alpha concentration 9-fold that produced by a single dose of 27.5 mg/kg. This dose, although higher than the MTD of 30 mg/kg, did not affect the health of mice at the time of assay (3 h). An interval of 1 day produced very low levels of serum TNF-alpha after the second injection. An interval of 3 days produced high levels of serum TNF-alpha after the second injection (9-fold that detected in mice receiving 27.5 mg/kg in a single dose) but no long-term toxicity, whereas an interval of 7 days produced an intermediate response. Thus, the first dose can either potentiate or suppress the TNF-alpha response to a second dose. Mice with advanced subcutaneous colon 38 tumours were treated either with a single dose of DMXAA (27.5 mg/kg) or with a divided dose (two doses of 27.5 mg/kg given 3 days apart). Both the cure rate and the tumour-growth delay were enhanced by the divided-dose schedule. The results are relevant to the design of clinical administration schedules of DMXAA and emphasise the importance of TNF-alpha induction in the antitumour response.

Pharmacodynamics of daily subcutaneous recombinant human interleukin-3 in normal volunteers

Normal volunteers received subcutaneous injections of recombinant human interleukin-3 (rhIL-3) on 4 consecutive days to characterize toxicity, pharmacokinetics, and hematopoietic effects. Dosages were 2.5, 5.0, and 7.5 micrograms/kg/day (n = 6 subjects per group). Adverse effects consisted predominantly of flu-like symptoms such as fever and headache. Mean area under the serum concentration-time curve and maximum serum concentration were linearly related to dose. Serum clearance was not apparently related to dose. Clearance increased slightly but significantly between days 1 and 4. Rapid but modest elevations in neutrophil and eosinophil counts were observed during treatment. Mean platelet counts rose modestly, peaking on day 10. Increases of CD34+ cell counts were correlated with increases of colony-forming unit-granulocyte macrophage (peak, day 7).

GM-CSF promotes proliferation of human fetal and adult microglia in primary cultures

Proliferation of microglia/macrophages is a common finding in many central nervous system diseases. To identify mitogenic signals for human microglia, we examined primary cultures of human fetal and adult microglia after stimulation with cytokines, colony stimulating factors (CSFs), or LPS, using proliferating cell nuclear antigen (PCNA) expression as an index of cell proliferation. The results showed that both M-CSF and GM-CSF induced microglial proliferation in fetal and adult human cultures, but that GM-CSF provided a much stronger stimulus. At 96 h post-stimulation, the mean PCNA labeling index was 2.4 for M-CSF and 13.3 for GM-CSF in fetal microglia; in adult microglia, the PCNA labeling index was 4.7 for M-CSF and 9.0 for GM-CSF. The effect of GM-CSF on fetal microglia was dose dependent and synergistic with M-CSF. LPS abolished the basal level of PCNA labeling in adult microglia, but in fetal microglia, caused a slight increase in PCNA labeling (1.9) at 96 h and consistently enhanced microglial cell survival and differentiation into highly branched cells. The production of GM-CSF in purified human fetal astrocyte and microglial cultures was examined after stimulation with LPS, TNF-alpha, or IL-1 beta. Unlike M-CSF, neither cell type produced GM-CSF in unstimulated cultures; however, when stimulated with IL-1 beta, astrocytes expressed GM-CSF mRNA and protein, which accumulated in the culture through 72 h. In microglia, LPS was the only effective inducing agent. An immunocytochemical study performed to identify in vivo sources of GM-CSF revealed selective labeling of reactive astrocytes in active lesions of multiple sclerosis and senile plaques of Alzheimer's disease. Our data demonstrate that both fetal and adult human microglia are capable of proliferation in response to CSFs, GM-CSF being the more effective stimulus.

Interleukin-3 administration enhances human monocyte function in vivo

In addition to its haemopoietic effects, interleukin-3 (IL-3) enhances leucocyte function in vitro. In this study we examined the effects on haematological variables and monocyte function of a single IL-3 infusion in five haematologically normal individuals. There was a rapid fall in circulating monocyte (to 24 +/- 6% of pre-infusion value) and eosinophil numbers (to 3 +/- 2%) with a nadir at 30 min and gradual return to baseline over 6 h. No significant changes in monocyte expression of the adhesion molecules CD11b or L-selectin or of monocyte respiratory burst activity were detected. There was a significant increase in monocyte phagocytosis and killing of Candida after IL-3 infusion: the percentage of monocytes which had ingested Candida increased from 39 +/- 10% to 62 +/- 12% and the total number of Candida killed per 100 monocytes increased from 63 +/- 34 to 210 +/- 59 (P < 0.05 and P < 0.01 respectively). There was no inhibition of neutrophil migration into a 'skin window' site and monocyte migration was moderately enhanced (peak increase of 260 +/- 47%). These results show that IL-3 has significant effects on monocyte function in vivo and could be of use in augmenting host defence mechanisms in immunocompromised patients.

Serum levels of granulocyte-colony stimulating factor (G-CSF) in bacterial and viral infections, and in atypical pneumonia

Serum granulocyte-colony stimulating factor (G-CSF) was measured with an ELISA method in patients with acute bacterial and viral infections, or with an atypical pneumonia. Before initiation of antibiotic treatment, G-CSF was found to be significantly increased (799 +/- 1501 ng/l) in sera from 34 patients with an acute bacterial infection compared with the 27 patients with a viral infection (58 +/- 34 ng/l; P < 0.001) and with the eight patients with an atypical pneumonia (60 +/- 33) ng/l; P < 0.001). No significant difference in G-CSF levels was seen between gram-positive and gram-negative bacterial infections. In septic shock, increased G-CSF levels were seen both in patients with leucocytosis and leucopenia. In uncomplicated bacterial infections, both G-CSF and IL-6 were increased on day 0, and decreased rapidly after initiation of antibacterial therapy and before the patients became afebrile. In bacterial infections on day 0, G-CSF levels correlated with mononuclear cells (rs = -0.62, P < 0.001), IL-6 (rs = 0.40, P < 0.05) and S-MPO (rs = -0.5, P < 0.01). In viral infections, G-CSF was correlated with mononuclear cells (rs = 0.41, P < 0.05), white blood cell counts (rs = 0.56, P < 0.01), neutrophils (rs = 0.41, P < 0.05) and CRP (rs = 0.47, P < 0.05). We conclude that G-CSF is rapidly raised in the blood in acute bacterial infections but not in acute viral infections or in infections with Mycoplasma pneumonia. Our results also support the theory that G-CSF is involved in the mechanisms of mobilization of neutrophils into the peripheral circulation.

Phase II study of glycosylated recombinant human granulocyte colony-stimulating factor after HLA-identical sibling bone marrow transplantation

BACKGROUND

The lengthy period of neutropenia which follows allogeneic bone marrow transplantation (BMT) results in significant morbidity and some mortality. Recombinant human granulocyte colony-stimulating factor (rhuG-CSF) effectively reduces neutropenia and morbidity when given after autologous BMT, but has not been adequately investigated in allografts.

AIMS

To assess the tolerability, safety and efficacy of rhuG-CSF after allogeneic BMT.

METHODS

rhuG-CSF was administered to 13 adult patients with haematological malignancies after HLA-identical sibling BMT. Five micrograms/kg of rhuG-CSF was given daily by subcutaneous bolus injection, commencing four hours after marrow infusion and continuing until the neutrophil count was > or = 1.0 x 10(9)/L on three consecutive days. Graft-versus-host disease (GVHD) prophylaxis was cyclosporin and short-course methotrexate (days 1, 3, 6 and 11). Prophylactic intravenous (IV) antibiotics were administered from the onset of neutropenia. The control group consisted of patients with comparable diagnoses, transplanted before and after the current study using identical supportive care and GVHD prophylaxis policies.

RESULTS

Although time to recovery of the neutrophil count to > 0.1 x 10(9)/L was similar, the rhuG-CSF-treated patients experienced accelerated recovery to > 0.5 x 10(9)/L, which occurred at a median of 15 days (range 11-21) after marrow infusion in study patients compared to 18.5 days (range 14-41) in the controls (p = 0.04). No significant differences were detected in any of the indices of transplant-related morbidity examined, including the number of days of fever, the incidence of culture-positive infections, the usage of antibiotics, the requirement for parenteral nutrition and IV morphine, the maximum severity of mucositis and GVHD, and the day of discharge.

CONCLUSION

Within the context of this study, rhuG-CSF had limited impact on the clinical outcome of HLA-identical sibling BMT.

Concurrent RhGM-CSF does not offset myelosuppression from intensive chemotherapy: randomized placebo-controlled study in childhood acute lymphoblastic leukemia

To determine whether recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) can offset the myelosuppressive effects of intensive chemotherapy, we carried out a double-blind placebo-controlled trial in which 40 patients with acute lymphoblastic leukemia (ALL) were randomized into two groups of 20 each. One group received rhGM-CSF (5.5 micrograms/kg SC) coadministered with chemotherapy and the other, placebo coadministered with chemotherapy from day 5 to day 11 and from day 19 to day 25 of the 28-day intensification phase of our institutional high-risk protocol for childhood ALL. The results indicate that, at the dose and schedule used, rhGM-CSF did not prevent neutropenia or shorten the number of days required to complete this phase of therapy. In addition, the treated and placebo groups showed no significant difference in absolute neutrophil counts, number of days with neutropenia, number of days with fever, number of days spent in hospital, or number of days on antibiotics during the 28-day study period. There was also no difference between the two groups in the number, type, or severity of infectious episodes. Two of 20 patients in the treatment group have relapsed, whereas none of the patients in the placebo group has yet relapsed (follow-up: 3-37 months), but these events were not statistically significant. We conclude that treatment with rhGM-CSF at the dose and schedule employed is not clinically beneficial.

Subtypes of inositol 1,4,5-trisphosphate receptor in human hematopoietic cell lines: dynamic aspects of their cell-type specific expression

Inositol 1,4,5-trisphosphate (IP3)-mediated Ca2+ signaling plays important roles in cellular responses to extracellular stimuli. We recently succeeded in cloning human counterparts of the three subtypes derived from separate genes. Using the cDNA sequences type-specific to these subtype receptors, we here analyzed the expression profile of IP3R subtypes in stimulated and unstimulated human hematopoietic cell lines representing T cells, B cells, neutrophils, macrophages, erythrocytes and megakaryocytes. Northern and dot blot analysis showed that each IP3R subtype is expressed differently in these cells and that the expression profile in each cell is dynamically changed upon stimuli which induce differentiation. Moreover, most of these cells were found to simultaneously express at least two different subtype receptors.

Pulmonary delivery of powders and solutions containing recombinant human granulocyte colony-stimulating factor (rhG-CSF) to the rabbit

Two powder formulations (MMAD < 4 microns) containing rhG-CSF were insufflated (IF) via an endotracheal tube at doses of 5, 75 or 500 micrograms/kg to New Zealand white rabbits. Doses of 5 and 500 micrograms/kg of solutions were administered by intratracheal instillation (IT), subcutaneous (SC) injection in the thigh and intravenous injection (i.v.) via the marginal ear vein. Blood samples were removed at regular intervals from an indwelling jugular catheter. Blood was analyzed directly for total white blood cell counts (WBC). Plasma was assayed for rhG-CSF by a specific ELISA. The distribution of radioactive dose in lung tissue was found after administering Tc99m HSA in solution or when incorporated into powders. The pharmacokinetics and pharmacodynamics were determined for all routes of administration. High dose IV concentration vs. time profiles declined biexponentially (t1/2 alpha = 0.6 +/- 0.2 hrs, t 1/2 beta = 4.6 +/- 0.2 hrs, n = 8). Clearance was does dependent (11.6 +/- 2.6 [500 micrograms/kg, n = 8] vs; 21.8 +/- 3.3 ml/hr/kg [5 micrograms/kg, n = 5]). A normal systemic response was obtained after IF, indicating that rhG-CSF retains activity in the solid state. Dissolution and absorption of rhG-CSF from the powders were not rate limiting. The plasma concentration vs. time profiles peaked at similar times to those after IT (Tmax 1-2 hrs) but were earlier than obtained after SC (Tmax 6-10 hrs). Powders were less efficiently dosed to the lung lobes after insufflation compared with instillates (14.7 +/- 10.5 vs. 60.1 +/- 10.6%), resulting in bioavailabilities ranging from 5 to 33%.(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukin 13: novel role in direct regulation of proliferation and differentiation of primitive hematopoietic progenitor cells

The recently cloned interleukin 13 (IL-13) shares most investigated biological activities on B lymphocytes and monocytes with IL-4. In this study we investigated for the first time the potential role of IL-13 in the regulation of the growth of hematopoietic progenitor cells. IL-13 enhanced stem cell factor (SCF)-induced proliferation of Lin-Sca-1+ bone marrow progenitor cells more potently than IL-4. The effect of IL-13 was purely synergistic, since IL-13 alone stimulated no colony formation. Single cell experiments suggested that the synergistic effect of IL-13 on Lin-Sca-1+ progenitors was directly mediated. In contrast, IL-13 had no synergistic activity on SCF-induced proliferation of the more mature Lin-Sca-1- progenitor cells. Thus, the cloning frequency in response to SCF + IL-13 was at least 20-fold higher in the Lin-Sca-1+ than the Lin-Sca-1- progenitor cell population. Furthermore, IL-13 but not IL-4 synergistically enhanced colony formation of Lin-Sca-1+ progenitors in response to granulocyte/macrophage colony-stimulating factor (GM-CSF) (threefold), whereas both IL-4 and IL-13 enhanced G-CSF-induced colony formation (threefold), and neither of the two significantly affected CSF-1 and IL-3-induced proliferation. Finally, whereas stimulation of Lin-Sca-1+ progenitors by SCF + G-CSF resulted in the formation of 90% granulocytes, the addition of IL-13 resulted in the production of macrophages exclusively. This novel effect on differentiation was directly mediated, shared with IL-4, and could not be observed on Lin-Sca-1- progenitor cells. Collectively, these findings indicate a novel role of IL-13 in early myelopoiesis, partially overlapping but also different from that of IL-4.

Upregulation of the surface expression of two integrins and induction of chemotactic activity in a human leukemic cell line by Oncoimmunin-M

Previously, it was shown that Oncoimmunin-M (OI-M), a recently identified tumor cell-derived 36 kDa protein, is able both to inhibit the proliferation of the human promyelocytic leukemic cell line HL-60 while maintaining viability in culture and to induce a bimodal distribution of CD11b, the alpha chain of the integrin MAC-1, on the cell surface (Packard, B.Z. and Komoriya, A. (1993) J. Biol. Chem. 268, 6356-6363). Now, data which reveal that exposure of HL-60 cells to this factor also brings about an increase in the mean level of surface expression of CD11c, the alpha chain of another leukocyte integrin (p150,95), but leaves CD11a, the alpha chain of the third leukointegrin (LFA-1), virtually unchanged (< 10%) are presented. Comparison of motility studies of OI-M-treated HL-60 bulk populations with control bulk populations demonstrates coinduction of CD11b and CD11c surface upregulation with chemotactic responsiveness to a gradient of the chemoattractant human C5a. Separation of motile from nonmotile cell subpopulations after exposure to C5a further reveals that individual cells which respond to this chemoattractant express increased levels of both CD11b and CD11c relative to unresponsive cells. These data correlate the upregulation of leukointegrins MAC-1 and p150,95 by a tumor cell-derived protein on a preterminally differentiated myeloid cell with chemotactic responsiveness to human C5a.

Human cytomegalovirus infection of the monocyte/macrophage lineage in bone marrow

Peripheral blood monocytes (PBM) are one site of persistence of human cytomegalovirus (HCMV) in healthy carriers. However, because PBM circulate only briefly before entering the tissues and are difficult to infect with HCMV, it has been suggested that they may acquire HCMV during development in the bone marrow. Consistent with this, we show evidence that bone marrow progenitors from healthy HCMV carriers contain endogenous HCMV DNA as detected by PCR. We also show that bone marrow precursors are readily infected by clinical isolates of HCMV in vitro but that no viral gene expression occurs until these cells become differentiated. In contrast, incubation of these cells at any developmental stage with the laboratory strain AD169 resulted in few cells expressing viral immediate-early genes, and this correlated with a lack of entry of AD169 virus. These observations are consistent with bone marrow progenitors acting as a reservoir for HCMV and transmitting the viral genome to PBM, in the absence of lytic-gene expression, until they leave the circulation and undergo tissue-specific differentiation to macrophages.

All-trans- and 9-cis-retinoic acid: potent direct inhibitors of primitive murine hematopoietic progenitors in vitro

Retinoic acid (RA) stimulates the clonal proliferation of mature bone marrow progenitor cells and inhibits the growth of leukemic progenitors, whereas its effects on normal primitive hematopoietic progenitors have not yet been investigated. This study investigated the ability of all-trans- and 9-cis-RA to modulate the proliferation and differentiation of murine Lin-Sca-1+ bone marrow progenitor cells. Both RA isoforms inhibited in a reversible and dose-dependent fashion, the proliferation of multi- but not single-factor responsive Lin-Sca-1+ progenitor cells. The 50% effective dose was 10 nM for both all-trans- and 9-cis-RA. Maximum inhibition was observed at 100-1,000 nM RA, resulting in a 50-75% reduction in the number of proliferative clones. Lin-Sca-1+ cells with high proliferative potential were preferentially inhibited by RA, resulting in a 80-100% inhibition depending on the hematopoietic growth factors stimulating their growth. The inhibitory effects of RA were directly mediated on the target cell, since the effects were observed at the single cell level. Furthermore, autocrine transforming growth factor beta (TGF-beta) production can probably not account for the observed inhibitory effects of RA, since a TGF-beta neutralizing antibody did not block RA-induced inhibition. Whereas RA, in general, is a differentiation-inducing agent, treatment of Lin-Sca-1+ progenitors resulted in the accumulation of an increased fraction of blasts and immature myeloid cells. Thus, RA inhibits the proliferation as well as differentiation of normal primitive hematopoietic progenitor cells.

Effects of recombinant human granulocyte-colony stimulating factor on neutropenic mice infected with Candida albicans: acceleration of recovery from neutropenia and potentiation of anti-C. albicans resistance

The treatment of systemic candidal infection in neutropenic patients continues to be a major problem, and only 20% of patients survive despite treatment with amphotericin B (Amph B). Granulocyte colony-stimulating factor (G-CSF) is a haemopoietic glycoprotein that appears to control the survival, cycle, activation, proliferation and maturation of neutrophil granulocytes and promoter recovery from neutropenia. Confirming previous results, we observed that subcutaneous (s.c.) injection of recombinant human (rh) G-CSF in mice (30 micrograms kg-1 daily) increased the circulating leucocyte count (fourfold) on day 5 of treatment, and led to an expansion of the bone marrow myeloid compartment. The in vivo effect of rhG-CSF on murine resistance to systemic Candida albicans infection was also studied in neutropenic mice. Neutropenia was induced by intraperitoneal injection of a single dose of cyclophosphamide (CPA, 200 mg kg-1) 4 days before C. albicans infection and 2 days before rhG-CSF treatment. rhG-CSF administration showed a protective role on mice infected intravenously (i.v.) with one million C. albicans spores; all the untreated control mice died within 8 days after infection, whereas about 40% of mice treated with rhG-CSF remained alive for the same period. Furthermore, the survival rate was greater in host animals treated with combined Amph B and rhG-CSF than in those treated with Amph B alone. The number of C. albicans colony-forming units (CFU-C. albicans) in the kidney of infected mice was lower in the rhG-CSF-treated group than in the non-treated control mice. This suggests that the severity of infection is decreased in rhG-CSF-treated host animals.

Macrophage colony-stimulating factor restores bone resorption in op/op bone in vitro in conjunction with parathyroid hormone or 1,25-dihydroxyvitamin D3

The in vivo administration of macrophage colony-stimulating factor (M-CSF) restores osteoclastogenesis and bone resorption in the op/op murine osteopetrosis. In vitro, exogenous M-CSF has been shown to be necessary for the generation of osteoclast-like cells in cocultures of hematopoietic and mesenchymal cells obtained from this mutant. In this study we investigated the capacity of M-CSF and other cytokines and hormones, alone or in combination, to induce bone resorption in explants of op/op metatarsals and metacarpals prelabeled with 45Ca. The effect on bone resorption was verified by counting the number of osteoclasts generated in the mineralized matrix. No osteoclast formation and no bone resorption were observed in the absence of M-CSF. M-CSF alone had only a slight effect at the high concentration of 10(4) units/ml. Addition of PTH or 1,25-(OH)2D3 together with M-CSF induced both osteoclastogenesis and bone resorption. The release of 45Ca was linear with time up to 15 days. PTH or 1,25-(OH)2D3 could not be substituted by TNF-alpha or IL-1, whereas IL-6 had a weak effect. M-CSF could not be replaced by GM-CSF. This study further emphasizes the role of M-CSF, PTH, and 1,25-(OH)2D3 in osteoclastogenesis.

Distinct cytoplasmic regions of the human granulocyte colony-stimulating factor receptor involved in induction of proliferation and maturation

The granulocyte colony-stimulating factor receptor (G-CSF-R) transduces signals important for the proliferation and maturation of myeloid progenitor cells. To identify functionally important regions in the cytoplasmic domain of the G-CSF-R, we compared the actions of the wild-type receptor, two mutants, and a natural splice variant in transfectants of the mouse pro-B cell line BAF3 and two myeloid cell lines, 32D and L-GM. A region of 55 amino acids adjacent to the transmembrane domain was found to be sufficient for generating a growth signal. The immediate downstream sequence of 30 amino acids substantially enhanced the growth signaling in the three cell lines. In contrast, the carboxy-terminal part of 98 amino acids strongly inhibited growth signaling in the two myeloid cell lines but not in BAF3 cells. Truncation of this region lead to an inability of the G-CSF-R to transduce maturation signals in L-GM cells. An alternative carboxy tail present in a splice variant of the G-CSF-R also inhibited growth signaling, notably in both the myeloid cells and BAF3 cells, but appeared not to be involved in maturation.

Effects of gamma-irradiation on the M-CSF-promoter linked to a chloramphenicol aminoacyl transferase reporter gene expressed in a clonal murine bone marrow stromal cell line

The effects of cytokines produced by bone marrow stromal cells on closely associated hematopoietic cells constitute a major component of the physiology of the hematopoietic microenvironment. A major cytokine produced by marrow stromal cells is macrophage colony-stimulating factor (M-CSF). To determine the effect of gamma-irradiation on the M-CSF promoter in bone marrow stromal cells, we selected a clonal cell line from the C3H/HeJ mouse marrow stromal cell line D2XRII and stably transfected a reporter construct containing the murine M-CSF-promoter linked to a chloramphenicol aminoacyl transferase (CAT) gene. CAT activity was measured at serial time points after gamma-irradiation in vitro to doses between 500 and 10,000 cGy at a dose rate of 116 cGy/min. D2XRII marrow stromal cells treated with phorbol myristate acetate (40 micrograms/ml, four h), demonstrated a significant two-fold increase in CAT activity. In contrast, CAT activity measured immediately, 24 h, 72 h or 1 week after gamma-irradiation, showed no significant increase or decrease in CAT activity. An increase in CAT activity was detected 48 h after irradiation with cells that received 5,000 cGy. Thus, single fraction gamma-irradiation of plateau phase bone marrow stromal cells did not decrease M-CSF-promoter activity. These results are consistent with prior experimental data demonstrating stable levels of release of M-CSF protein following gamma-irradiation of bone marrow stromal cells and imply that the stability of transcription of the gene for this important cytokine is protected from irradiation.

Molecular and cellular effects of hexadecylphosphocholine (Miltefosine) in human myeloid leukaemic cell lines

The molecular and cellular effects of the anti-neoplastic alkylphospholipid hexadecylphosphocholine (Miltefosine, MIL) on parameters associated with growth and differentiation of human myeloid leukaemic cell lines U937, KG1 and KG1a were investigated. On a cellular level, MIL has dose-dependent differentiation-inducing growth-promoting and cytotoxic activities exemplified by induction of respiratory burst activity, stimulation of interleukin-3 (IL-3)/granulocyte-macrophage colony stimulating factor (GM-CSF)-dependent growth of the KG1 cell line in soft agar culture, inhibition of cellular net growth and finally cell death. By northern blot analysis, transcription of functional receptors for IL-3, GM-CSF, G-CSF and FcRI were studied. It was shown that MIL has stimulatory activity on IL-3 and GM-CSF receptor gene transcription. In addition, the transcription of proliferation- and differentiation-associated proteins, namely histone subtypes, c-myc and NF-kappa B p50, were studied. MIL suppressed c-myc and enhanced NF-kappa B p50 transcription in the U937 cell line, comparable to the well-characterised differentiation-inducing phorbolester 12-O-tetradecanoylphorbol-13-acetate (TPA). We conclude that the interaction of MIL with its molecular target(s) in myeloid cells induces molecular and cellular effects associated with induction of differentiation, distinct from its cytotoxic activity.