Reciprocal inhibition of binding between interleukin 3 and granulocyte-macrophage colony-stimulating factor to human eosinophils

125I-labeled recombinant human interleukin 3 (IL-3) bound, at 4 degrees C, to a single class of high-affinity receptors on human eosinophils with an apparent dissociation constant (Kd) of 470 pM, but it did not bind to human neutrophils. 125I-labeled recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) also bound to a single class of high-affinity receptors on eosinophils with an apparent Kd of 44 pM and on neutrophils with an apparent Kd of 70 pM. These binding characteristics were consistent with the biological activities of IL-3 and GM-CSF on eosinophils and with the lack of stimulation of neutrophil function by IL-3. Specificity studies under conditions shown to prevent receptor internalization showed that the binding of 125I-labeled IL-3 to eosinophils was partially inhibited by GM-CSF but not by other cytokines. Reciprocal experiments with 125I-labeled GM-CSF showed that IL-3 but not other cytokines partially inhibited binding to eosinophils. In contrast, the binding of 125I-labeled GM-CSF to neutrophils was not inhibited by IL-3 or other cytokines tested. Quantitative inhibition binding experiments on eosinophils showed that the reciprocal inhibition between IL-3 and GM-CSF was not complete up to a concentration of heterologous ligand of 100 nM. These results show that (i) IL-3 binds to eosinophils but not neutrophils and (ii) IL-3 and GM-CSF specifically interact on the surface of eosinophils, providing a possible mechanism for the overlapping activities of IL-3 and GM-CSF on these cells.     

Ligation of CD69 induces apoptosis and cell death in human eosinophils cultured with granulocyte-macrophage colony-stimulating factor

Peripheral blood (PB) eosinophils rapidly undergo apoptosis and cell death in vitro unless cultured in the presence of cytokines such as granulocyte-macrophage colony-stimulating factor (GM-CSF) in which their survival is prolonged for up to 10 days. CD69 is a type II membrane antigen expressed by cytokine-activated, but not freshly isolated, PB human eosinophils. We have examined the effect of ligation of CD69 by specific monoclonal antibody (MoAb) on the viability of human eosinophils cultured with recombinant human (rh)GM-CSF. Eosinophils were purified by immunomagnetic selection and cultured with GM-CSF (10(-10) mol/L). Eighteen hours after the start of culture, a panel of CD69 MoAb or controls (anti-CR3 or isotype-matched control MoAb) were added. Viability was assessed by trypan blue exclusion and apoptosis by morphologic assessment, DNA laddering, and flow cytometric analysis of eosinophil red autofluorescence. Up to 50% of the eosinophils had undergone apoptosis 48 hours after addition of anti- CD69 MoAb compared with less than 10% apoptosis for CR3 or the isotype matched control. The majority of apoptotic eosinophils excluded trypan blue at 48 hours post CD69 ligation. More apoptotic eosinophils were observed at later time-points and this was associated with loss of viability. At 120 hours post-addition of the anti-CD69 MoAb MLR3, 24% +/- 10.6% eosinophils were viable compared with 84% +/- 3.4% for the CR3 control (P < .001). A F(ab)2 fragment of CD69 MoAb P8, also induced apoptosis in GM-CSF cultured eosinophils. A more rapid induction of eosinophil apoptosis was obtained with CD69 MoAb immobilized via their Fc portions on protein-A coated plastic 96 well plates. Ligation of CD69 or CR3 resulted in the release of comparable quantities of eosinophil peroxidase at 48 hours post-ligation. These levels of EPO were consistent with the viability of these cells at 48 hours as assessed by exclusion of trypan blue. Finally, a neutralizing MoAb to TGF beta 1 had no effect on CD69-dependent apoptosis induction nor were there detectable quantities of TGF beta 1 in supernatants from GM-CSF-- cultured eosinophils ligated with CD69 or control MoAb. These results suggest that eosinophils cultured with GM-CSF can be induced to undergo apoptosis as a result of cell signalling mediated by perturbation of CD69. This may represent an important physiologic mechanism for eosinophil removal in vivo.     

Specific human granulocyte-macrophage colony-stimulating factor antagonists.

Human granulocyte-macrophage colony-stimulating factor (GM-CSF) is a pleiotropic hemopoietic growth factor and activator of mature myeloid cell function. We have previously shown that residue 21 in the first helix of GM-CSF plays a critical role in both biological activity and high-affinity receptor binding. We have now generated analogues of GM-CSF mutated at residue 21, expressed them in Escherichia coli, and examined them for binding, agonistic, and antagonistic activities. Binding experiments showed that GM E21A, E21Q, E21F, E21H, E21R, and E21K bound to the GM-CSF receptor alpha chain with a similar affinity to wild-type GM-CSF and had lost high-affinity binding to the GM-CSF receptor alpha-chain-common beta-chain complex. From these mutants, only the charge reversal mutants E21R and E21K were completely devoid of agonistic activity. Significantly we found that E21R and E21K antagonized the proliferative effect of GM-CSF on the erythroleukemic cell line TF-1 and primary acute myeloid leukemias, as well as GM-CSF-mediated stimulation of neutrophil superoxide production. This antagonism was specific for GM-CSF in that no antagonism of interleukin 3-mediated TF-1 cell proliferation or tumor necrosis factor alpha-mediated stimulation of neutrophil superoxide production was observed. E. coli-derived GM E21R and E21K were effective antagonists of both nonglycosylated and glycosylated wild-type GM-CSF. These results show that low-affinity GM-CSF binding can be dissociated from receptor activation and have potential clinical significance for the management of inflammatory diseases and certain leukemias where GM-CSF plays a pathogenic role.     

Treatment of active Crohn's disease with recombinant human granulocyte-macrophage colony-stimulating factor

Treatment for Crohn's disease is aimed at immunosuppression. Yet inherited disorders associated with defective innate immunity often lead to development of a Crohn's-like disease. We performed an open-label dose-escalation trial (4-8 microg/kg per day) to investigate the safety and possible benefit of granulocyte-macrophage colony-stimulating factor (GM-CSF) in the treatment of 15 patients with moderate to severe Crohn's disease. No patients had worsening of their disease. Adverse events were negligible and included minor injection site reactions and bone pain. Patients had a significant decrease in mean Crohn's disease activity index (CDAI) score during treatment (p<0.0001). After 8 weeks of treatment, mean CDAI had fallen by 190 points. Overall, 12 patients had a decrease in CDAI of more than 100 points, and eight achieved clinical remission. Retreatment was effective, and treatment was associated with increased quality-of-life measures. GM-CSF may offer an alternative to traditional immunosuppression in treatment of Crohn's disease.     

Immunization with recombinant human granulocyte-macrophage colony-stimulating factor as a vaccine adjuvant elicits both a cellular and humoral response to recombinant human granulocyte-macrophage colony-stimulating factor

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is an important cytokine for the generation and propagation of antigen-presenting cells and for priming a cellular immune response. We report here that use of recombinant human GM-CSF (rhGM-CSF), administered as an adjuvant in a peptide-based vaccine trial given monthly by intradermal injection, led to the development of a T-cell and antibody response to rhGM-CSF. An antibody response occurred in the majority of patients (72%). This antibody response was not found to be neutralizing. In addition, by 48-hour delayed type hypersensitivity (DTH) skin testing, 17% of patients were shown to have a cellular immune response to the adjuvant rhGM-CSF alone. Thymidine incorporation assays also showed a peripheral blood T-cell response to rhGM-CSF in at least 17% of the patients. The generation of rhGM-CSF-specific T-cell immune responses, elicited in this fashion, is an important observation because rhGM-CSF is being used as a vaccine adjuvant in various vaccine strategies. rhGM-CSF-specific immune responses may be incorrectly interpreted as antigen-specific immunity, particularly when local DTH responses to vaccination are the primary means of immunologic evaluation. We found no evidence of hematologic or infectious complications as a result of the development of rhGM-CSF-specific immune responses.     

Outcomes of granulocyte colony-stimulating factor or granulocyte-macrophage colony-stimulating factor use in neutropenic patients infected with human immunodeficiency virus

Objective: To characterize the effects of granulocyte colony-stimulating factor (G-CSF) or granulocyte-macrophage colony-stimulating factor (GM-CSF) on clinical outcomes in neutropenic HIV-infected patients, by means of a retrospective cohort study at an urban teaching hospital.Method: Data were reviewed from all patients discharged between January 1, 1996, and August 31, 1997, with human immunodeficiency virus and neutropenia (absolute neutrophil count (ANC) <1000 cells/μL), with outcome measures of length of stay, infectious complications, and survival to discharge.Results: Of the 228 discharged patients who met selection criteria, 71 had received G-CSF or GM-CSF; 157 controls had not. Cases had lower CD4+ cell counts (30 vs. 54 cells/μL; P = 0.017) and lower nadir ANCs (372 vs. 579 cells/μL; P < 0.001). Granulocyte-CSF or GM-CSF usage was not associated with the frequency of site-related infections, fever, or sepsis (all P > 0.20). No difference was found in duration of hospitalization (23 vs. 21 days; P > 0.20). In a logistic regression model for survival to discharge, higher nadir ANC and CSF use were independently associated with improved survival (P = 0.034 and P = 0.026, respectively).Conclusion: Use of G-CSF or GM-CSF was associated with improved survival to discharge among hospitalized HIV-infected patients with neutropenia.     

Purification and characterization of a human T-lymphocyte-derived granulocyte-macrophage colony-stimulating factor

We have examined the biologic and physical properties of a human T- lymphocyte granulocyte-macrophage colony-stimulating factor (CSF). The source of the factor is a T-lymphoblast cell line (Mo) that was derived from a patient with a T-cell variant of hairy-cell leukemia. The Mo line constitutively produces a number of lymphokines that are normally produced by mitogen-stimulated T lymphocytes. Medium conditioned by Mo cells grown in the absence of serum is especially rich in CSF activity, and using this source we have purified the CSF to a specific activity of about 3.5 x 10(6) colonies per 10(5) Ficoll-Hypaque-separated human bone marrow cells plated per mg protein. The Mo CSF stimulates the formation of both granulocyte and macrophage colonies in vitro (in about equal numbers) and it has a relatively steep dose-response curve. Both the crude and purified preparations stimulated the formation of eosinophil as well as neutrophil colonies; it is unclear whether this is due to the presence of multiple factors with similar physical properties or a single factor with multiple activities. The CSF has little stimulating activity for mouse bone marrow progenitors. Physically, the Mo CSF is an acidic glycoprotein of molecular weight about 34,000. It binds to concanavalin A-Sepharose, is unusually resistant to denaturing agents and heat treatment, and is not inactivated in the presence of sulfhydryl reagents. The Mo CSF is distinct from factors stimulating erythroid colony formation and inhibiting neutrophil migration that are also produced by Mo cells. It differs in several physical and biologic properties from other human CSFs that have been characterized.     

Regulation of human monocyte adherence by granulocyte-macrophage colony-stimulating factor.

Recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) was found to increase the adherence of purified peripheral blood monocytes to plastic surfaces and to monolayers of human umbilical vein endothelial cells. With plastic surfaces as a model 9-hr culture with GM-CSF was necessary for enhancement, and maximum levels were obtained after 24-hr stimulation. GM-CSF-stimulated adherence must require new RNA and protein synthesis because actinomycin D and cycloheximide abolished existing adherence and prevented further monocyte attachment. Interestingly, shorter incubations (1-2 hr) with cycloheximide increased adherence, suggesting a labile inhibitor. Formaldehyde fixation of monocytes but not of human vein endothelial cells abolished adherence, indicating the need for actively metabolizing monocytes. Thus, a hemopoietic growth factor, responsible for the proliferation and differentiation of monocytes, can also alter their adhesive characteristics. These observations may have important implications in pathological situations and in the in vivo use of GM-CSF.     

Pharmacokinetics of human granulocyte-macrophage colony-stimulating factor using a sensitive immunoassay

A sensitive and reliable sandwich enzyme-linked immunosorbent assay (ELISA) has been developed for recombinant human granulocyte-macrophage colony-stimulating factor (hGM-CSF). The assay is quantitative between 100 pg/mL and 2.5 ng/mL for bacterially synthesized hGM-CSF in human serum and is more sensitive and specific than the semisolid agar bioassay. As part of a phase I study, the pharmacokinetics of intravenous (IV) bolus injection and subcutaneous (SC) administration of hGM-CSF were studied. Following a single IV dose, an initial high blood level of hGM-CSF occurred, followed by a rapid decrease occurring in two apparent phases with a half-life (t1/2)alpha of less than five minutes and a t1/2 beta of 150 minutes. After an SC injection, detectable serum levels occurred within 15 to 30 minutes, and serum levels were sustained for a variable time depending on the dose. At the highest SC dose (10 micrograms/kg), a serum level of greater than 1 ng/mL (65 pmol/L) was maintained for greater than 12 hours after a single injection. This corresponds to the concentration of hGM-CSF supporting near-maximum proliferation in vitro.     

Stimulation of canine hematopoiesis by recombinant human granulocyte-macrophage colony-stimulating factor

The effect of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) on canine hematopoiesis was evaluated. rhGM-CSF stimulated granulocyte-macrophage colony formation of canine marrow depleted of accessory cells up to tenfold. Stimulation of colony formation was abrogated by anti-rhGM-CSF antiserum or heat inactivation. rhGM-CSF also stimulated in vivo canine hematopoiesis both when given as continuous i.v. infusion and as intermittent s.c. injections. Neutrophil, monocyte, and lymphocyte counts were increased three- to eightfold above controls, whereas values for eosinophils, reticulocytes, and hematocrits were not changed. Bone marrow histology after 2 weeks of treatment with rhGM-CSF showed hypercellularity with myeloid hyperplasia and left-shifted granulocytopoiesis. After discontinuation of rhGM-CSF, peripheral leukocyte counts returned to control level within 3-7 days. Platelet counts decreased rapidly after starting rhGM-CSF, to 5000-15,000 platelets/mm3, and increased within 24 h after stopping rhGM-CSF treatment, whereas marrow histology after 2 weeks of rhGM-CSF application showed the normal number and morphology of megakaryocytes.     

A highly sensitive quantitative bioassay for human granulocyte-macrophage colony-stimulating factor

Based on the granulocyte-macrophage colony-stimulating factor (GM-CSF) dependency of a newly established human myeloid cell line GM/SO, we developed a highly specific and sensitive bioassay for human GM-CSF. The presence of bioactive GM-CSF could be determined by measuring the formazan concentration produced from MTT by the cells that survived and proliferated in the presence of either natural or recombinant human GM-CSF. With this assay we were able to quantify the level of GM-CSF in two human sera as well as in conditioned media from human bladder cell carcinoma cell line 5637, a human fibroblast line, and phytohemagglutinin-stimulated peripheral blood mononuclear cells. The sensitivity of the assay allows measurement of concentrations of GM-CSF as low as 0.1 U/ml.     

Outcomes of granulocyte colony-stimulating factor or granulocyte-macrophage colony-stimulating factor use in neutropenic patients infected with human immunodeficiency virus.

OBJECTIVE: To characterize the effects of granulocyte colony-stimulating factor (G-CSF) or granulocyte-macrophage colony-stimulating factor (GM-CSF) on clinical outcomes in neutropenic HIV-infected patients, by means of a retrospective cohort study at an urban teaching hospital. METHOD: Data were reviewed from all patients discharged between January 1, 1996, and August 31, 1997, with human immunodeficiency virus and neutropenia (absolute neutrophil count (ANC) <1000 cells/mL), with outcome measures of length of stay, infectious complications, and survival to discharge. RESULTS: Of the 228 discharged patients who met selection criteria, 71 had received G-CSF or GM-CSF; 157 controls had not. Cases had lower CD4+ cell counts (30 vs. 54 cells/mL; P = 0. 017) and lower nadir ANCs (372 vs. 579 cells/mL; P < 0.001). Granulocyte-CSF or GM-CSF usage was not associated with the frequency of site-related infections, fever, or sepsis (all P > 0. 20). No difference was found in duration of hospitalization (23 vs. 21 days; P > 0.20). In a logistic regression model for survival to discharge, higher nadir ANC and CSF use were independently associated with improved survival (P = 0.034 and P = 0.026, respectively). CONCLUSION: Use of G-CSF or GM-CSF was associated with improved survival to discharge among hospitalized HIV-infected patients with neutropenia.     

In vivo effect of human granulocyte-macrophage colony-stimulating factor on megakaryocytopoiesis.

The effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on megakaryocytopoiesis and platelet production was investigated in patients with normal hematopoiesis. Three findings indicated that GM-CSF plays a role in megakaryocytopoiesis. During treatment with GM-CSF (recombinant mammalian, glycosylated; Sandoz/Schering-Plough, 5.5 micrograms protein/kg/d, subcutaneously for 3 days) the percentage of megakaryocyte progenitors (megakaryocyte colony forming unit [CFU-Mk]) in S phase (evaluated by the suicide technique with high 3H-Tdr doses) increased from 31% +/- 16% to 88% +/- 11%; and the maturation profile of megakaryocytes was modified, with a relative increase in more immature stage I-III forms. Moreover, by autoradiography (after incubation of marrow cells with 125I-labeled GM-CSF) specific GM-CSF receptors were detectable on megakaryocytes. Nevertheless, the proliferative stimulus induced on the progenitors was not accompanied by enhanced platelet production (by contrast with the marked granulomonocytosis). It may be suggested that other cytokines are involved in the regulation of the intermediate and terminal stages of megakaryocytopoiesis in vivo and that their intervention is an essential prerequisite to turn the GM-CSF-induced proliferative stimulus into enhanced platelet production.     

Developmental regulation of granulocyte-macrophage colony-stimulating factor production during human monocyte-to-macrophage maturation

Summary Cells of the macrophage lineage are a major source of various cytokines and hematopoietic growth factors. With regard to the growth factors acting on cells of their own lineage, macrophage colony-stimulating factor (M-CSF) has been proven to be secreted by monocytes (MO) and macrophages (MAC), whereas the production of granulocyte-macrophage colony-stimulating factor (GM-CSF) by human MO/MAC is under debate. Here we report that in elutriation-purified MO, as well as in MAC derived from cultured MO, GM-CSF m-RNA was regularly induced by LPS. In MO the GM-CSF message was still detectable 18h after stimulation under serum-free conditions, but in contrast was already lost at this time point in MAC. Secreted GM-CSF protein was detected in the culture medium using a sandwich ELISA. Furthermore, a factor-dependent cell line (M-07) was used for a biological assay. Here, a neutralizing anti GM-CSF antibody specifically blocked the proliferation-inducing activity of MO/MAC supernatants. Whereas only small amounts of GM-CSF were detected in MO, its secretion increased severalfold upon MO-to-MAC differentation in vitro. A similar increase upon in vitro maturation of MO was observed for the production of granulocyte colony-stimulating factor. The highest amounts of GM-CSF (up to 2.8 ng/10⁶ cells) were produced by MAC that had been derived from MO cultured under serum-free conditions in the presence of 0.5 mg/ml albumin as the only medium supplement.This work was supported by theDeutsche Forschungsgemeinschaft (AN 111).     

Recombinant and native human urinary colony-stimulating factor directly augments granulocytic and granulocyte-macrophage colony-stimulating factor production of human peripheral blood monocytes

Colony-stimulating factor from human urine (CSF-HU) has been purified to a homogeneous protein, and its complementary DNA (cDNA) has been cloned. Recombinant CSF-HU was prepared from a serum-free medium conditioned by Chinese hamster ovary cells transfected with the cDNA and purified by the same method as that for the native protein. Purified CSF-HU stimulated human bone marrow cells to form macrophage colonies. It also stimulated human mature monocytes prepared from peripheral blood of healthy volunteers to produce human active colony-stimulating activity that stimulates human bone marrow cells to form granulocyte and macrophage colonies. This activity was partially neutralized by the addition of both polyclonal antibodies against human granulocyte colony-stimulating factor and against human granulocyte-macrophage CSF, respectively. The stimulation of monocytes by CSF-HU was not inhibited by the addition of polymyxin-B, which is known as a potent inhibitor of endotoxin. On the other hand, CSF-HU did not stimulate monocyte production of interleukin-1 and interferon. These results indicate that recombinant and native CSF-HU stimulates immature cells as well as mature cells in the human monocyte lineage.