Recombinant human erythropoietin in combined treatment with granulocyte- or granulocyte-macrophage colony-stimulating factor in patients with myelodysplastic syndromes

PURPOSE: Myelodysplastic syndromes (MDS) are a heterogeneous group of hemopoietic progenitor cell disorders, and patients with MDS regularly develop anemia and frequently become transfusion-dependent. Treatment with erythropoietin (EPO) has been tried to correct anemia with only limited success with response rates ranging from 16% to 25%. However, it is becoming evident that the generally rather low response rate of EPO in patients with MDS will be improved by the combination of EPO with either G-CSF or GM-CSF. METHOD: Here, we analyzed the results from the literature (six papers and one abstract using EPO plus G-CSF, and seven papers using EPO plus GM-CSF). RESULTS: Among all trials the cytokine dose and schedule varied, and the response criteria were not uniform. The average response rate for improving anemia was 41% in 207 patients treated with EPO and G-CSF, and 26% in 154 patients treated with EPO and GM-CSF. There were higher response rates for refractory anemia (RA) (45%), ringed sideroblasts (RARS) (47%), and excess of blasts (RAEB) (38%) compared with blasts in transformation (RAEBT) (17%) for the treatment with EPO plus G-CSF. The corresponding response rates for treatment with EPO plus GM-CSF were 30% (RA), 29% (RARS), 16% (RAEB), and 0% (RAEBT), respectively. Prolonged administration even showed a higher increment in the response rates. CONCLUSION: In conclusion, the combination of EPO with G-CSF is probably superior to EPO plus GM-CSF. There seems to be a positive correlation between the duration of cytokine treatment and response rates, and higher response rates in early MDS stages compared to advanced entities. However, controlled studies are mandatory to evaluate the role of the combined cytokine treatment in patients with MDS.     

Opposing effects of PI3 kinase pathway activation on human myeloid and erythroid progenitor cell proliferation and differentiation in vitro

OBJECTIVE: To investigate 1) the effects of lineage-specific cytokines (G-CSF and EPO) combined with ligands for different classes of cytokine receptors (common beta chain, gp130, and tyrosine kinase) on proliferation by human myeloid and erythroid progenitor cells; and 2) the signal transduction pathways associated with combinatorial cytokine actions. PATIENTS AND METHODS: CFU-GM and BFU-E were cloned in vitro. Secondary colony formation by replated CFU-GM and subcolony formation by BFU-E provided measures of progenitor cell proliferation. Studies were performed in the presence of cytokine combinations with and without signal transduction inhibitors. RESULTS: Proliferation by CFU-GM and BFU-E was enhanced synergistically when common beta chain receptor cytokines (IL-3 or GM-CSF) were combined with G-CSF or EPO, but not with gp130 receptor cytokines (LIF or IL-6) or tyrosine kinase receptor cytokines (SCF, HGF, Flt-3 ligand, or PDGF). Delayed addition studies with G-CSF+IL-3 and EPO+IL-3 demonstrated that synergy required the presence of both cytokines from the initiation of the culture. The Jak2-specific inhibitor, AG490, abrogated the effect of combining IL-3 with EPO but had no effect on the enhanced CFU-GM proliferation stimulated by IL-3+G-CSF. The PI3 kinase inhibitors LY294002 and wortmannin substituted for G-CSF in combination with IL-3 since proliferation in the presence of LY294002/wortmannin+IL-3 was enhanced to the same extent as in the presence of G-CSF+IL-3. In contrast, LY294002 and wortmannin inhibited proliferation in the presence of EPO and in the presence of EPO+IL-3. CONCLUSION: 1) IL-3 may activate different signal transduction pathways when combined with G-CSF and when combined with EPO; 2) different signal transducing intermediates regulate erythroid and myeloid progenitor cell proliferation; and 3) inhibition of the PI3 kinase pathway suppresses myeloid progenitor cell differentiation and thereby increases proliferation.     

Effect of mast cell growth factor (c-kit ligand) on clonogenic leukemic precursor cells.

Mast cell growth factor (MGF), the ligand for the c-kit receptor, has been shown to be a hematopoietic growth factor that preferentially stimulates the proliferation of immature hematopoietic progenitor cells (HPC). We studied the effect of MGF on the in vitro growth of clonogenic leukemic precursor cells in the presence or absence of interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), and/or erythropoietin (EPO). Leukemic blood and bone marrow cells from patients with various types of acute myeloid leukemia (AML), chronic myeloid leukemia (CML) in chronic phase, as well as bone marrow samples from patients with myelodysplastic syndromes (MDS) were studied. MGF as a single factor did not induce significant colony formation by clonogenic leukemic precursor cells. In the presence of IL-3 and/or GM-CSF, MGF weakly stimulated the colony formation by clonogenic precursor cells from patients with AML. In contrast, in the presence of IL-3 and/or GM-CSF, MGF strongly induced both size and number of leukemic colonies from patients with CML in chronic phase. Furthermore, in the presence of EPO, MGF strongly stimulated erythroid colony formation by CML precursor cells. Cytogenetic analysis of the colonies showed that all metaphases after 1 week of culture were derived from the leukemic clone. In patients with MDS, MGF strongly stimulated myeloid colony formation in the presence of IL-3 and/or GM-CSF (up to fourfold), and erythroid colony formation in the presence of EPO (up to eightfold). Not only the number, but also the size of the colonies increased. In the presence of MGF, the percentage of normal metaphases increased in three patients tested after 1 week of culture compared with the initial suspension, suggesting that the normal HPC were preferentially stimulated compared with the preleukemic precursor cells. In the absence of exogenous EPO and in the presence of 10% human AB serum, MGF in the presence of IL-3 and/or GM-CSF induced erythroid colony formation from normal bone marrow and patients with MDS or CML, illustrating that MGF greatly diminished the EPO requirement for erythroid differentiation. These results indicate that MGF may be a candidate as a hematopoietic growth factor to stimulate normal hematopoiesis in patients with acute myeloid leukemia, or with myelodysplastic syndromes.     

Efficacy of a single,weekly dose of recombinant erythropoietin in myelodysplastic syndromes

Thirteen patients with low-to-intermediate risk myelodysplastic syndrome (MDS) received recombinant erythropoietin (r-EPO) at the single, weekly dose of 40.000 U for at least 8 weeks. Five patients (38.4%) achieved a major erythroid response (increased haemoglobin levels > 2 g/dl and/or transfusion independence), which is currently maintained after 3-11 months, without modification of r-EPO dose. This study suggests that 40.000 U r-EPO given once a week may be at least as effective as the more frequent (daily or three times a week) administrations of the drug usually employed in MDS patients.     

Sustained response to recombinant human erythropoietin and intermittent all-trans retinoic acid in patients with myelodysplastic syndromes

In vitro studies suggest that all-trans retinoic acid (ATRA) synergizes with erythropoietin (EPO) for the stimulation of hematopoiesis in patients with myelodysplastic syndrome (MDS). A clinical trial was performed to evaluate whether a combination of these agents was effective in relieving the cytopenias associated with MDS. Twenty-seven patients with low- or intermediate-risk MDS were enrolled in a 12-week study. ATRA was administered orally at the dose of 80 mg/m(2) per day in 2 divided doses for 7 consecutive days every other week. Recombinant human EPO was given subcutaneously 3 times a week. The EPO dose was initiated at 150 U/kg and was increased to 300 U/kg if after 6 weeks there was no or there was suboptimal erythroid response. Patients who responded to therapy were continued on ATRA and EPO at the same doses for 6 additional months (extension phase). Further treatment was given to patients with a continued response. Clinically significant erythroid responses with increases of hemoglobin levels of at least 1 g/dL or reduction of transfusion needs were seen in 13 (48%) patients, with 4 showing improved responses after dose escalation of EPO. Ten (37%) patients displayed continued responses during 6 months of extended treatment, and 7 (26%) are still responsive after a follow-up period of 13 months. Neutrophil responses were observed in 5 of 12 patients with neutropenia, and platelet responses were observed in 6 of 9 patients with thrombocytopenia. Three patients displayed trilineage responses that were sustained during continuation therapy. Side effects were observed in all patients but were of mild entity and did not require discontinuation of therapy. It is concluded that the combination ATRA + EPO is an effective and well-tolerated treatment for patients with low- and intermediate-risk MDS. The optimal ATRA and EPO schedule and the role of maintenance treatment remain to be determined and warrant further investigation.     

Effect of in vivo treatment with rh GM-CSF on in vitro growth of haematopoietic progenitors in patients with myelodysplastic syndromes.

BACKGROUND. Recombinant (r) human (h) granulocyte/macrophage colony stimulating factor (rh GM-CSF) has been shown to increase the number of peripheral blood (PB) neutrophils, eosinophils and monocytes in myelodysplastic syndromes (MDS). The aims of this study were: 1) to evaluate the effect of rh GM-CSF therapy on the in vitro growth of granulocyte-erythroid-macrophage-megakaryocyte colonies (CFU-GEMM), erythroid colonies (BFU-E), and granulocyte-macrophage colonies (CFU-GM) in patients with MDS; 2) to assess in these patients, while they are being treated in vivo with rh GM-CSF, the possible additive effect of rh IL-3 and rh G-CSF on the in vitro growth of haematopoietic progenitors. METHODS. The in vitro growth of CFU-GEMM, BFU-E and CFU-GM was studies in 10 myelodysplastic (MDS) patients, before and after in vivo administration of rh GM-CSF. RESULTS. After rh GM-CSF administration, the number of CFU-GM increased in all standard risk MDS patients. In 2 out of 5 cases, this effect was more pronounced and persisted up to 30 days after the end of rh GM-CSF treatment. On the other hand, the number of CFU-GEMM and BFU-E was substantially unchanged. When rh GM-CSF, rh G-CSF and rh IL-3 were added in vitro alone or in combination as the source of colony stimulating activity, no significant increase of the CFU-GM colony number was noticed. CONCLUSIONS. Rh GM-CSF therapy appears useful for increasing the number of peripheral blood granulocytes and of marrow CFU-GM in standard-risk MDS patients. High-risk MDS patients are far less responsive to rh GM-CSF treatment, probably reflecting a more aggressive and/or advanced disease.     

Recombinant human granulocyte-macrophage colony-stimulating factor plus erythropoietin for the treatment of cytopenias in patients with myelodysplastic syndromes

In vitro studies have indicated that granulocyte-macrophage colony-stimulating factor (GM-CSF) synergizes with erythropoietin (EPO) for the production of erythroid precursors in patients with myelodysplastic syndrome (MDS). We performed a clinical trial to evaluate whether the combination of these growth factors was effective in relieving the cytopenias associated with MDS. 31 anaemic patients with low and intermediate-risk primary MDS were enrolled in a 12-week study. Therapy was initiated with GM-CSF at 1 microgram/kg/d.s.c., and then adjusted to either normalize or double the absolute neutrophil count. EPO was given subcutaneously on alternate days starting from day 2. The EPO dose was initiated at 150 U/kg and increased to 300 U/kg if after 6 weeks there was no or suboptimal erythroid response. 26 patients completed the study treatment. All evaluable cases had a neutrophil response. Clinically significant erythroid responses with increases of haemoglobin levels of at least 1 g/dl and/or reduction of transfusion needs were seen in 9/26 (34.6%), five patients improving their response after dose escalation of EPO. Treatment had no apparent effect on mean platelet counts, a single case displaying a trilineage response. An elevated bone marrow erythroid infiltration and low concentrations of circulating tumour necrosis factor-alpha were the only predictors of haemoglobin response both in univariate and in multivariate analysis. We conclude that the combination GM-CSF + EPO can abrogate neutropenia and substantially relieve transfusion requirements in a large proportion of patients with low and intermediate risk MDS. However, in vivo synergy between these growth factors for the production of erythroid precursors is not supported by our data.     

Prospective, randomized trial of sequential interleukin-3 and granulocyte- or granulocyte-macrophage colony-stimulating factor after standard-dose chemotherapy in cancer patients.

BACKGROUND AND OBJECTIVE: Several in vitro and animal studies have shown that IL-3 primes hematopoietic stem cells to become more sensitive to later acting growth factors. We wanted to compare the toxicity and the synergistic stimulatory effect of interleukin-3 (IL-3) followed by granulocyte colony-stimulating factor (G-CFS) or granulocyte-macrophage colony-stimulating factor (GM-CSF) on white blood cell (WBC) and platelet counts, after standard-dose chemotherapy (CT) in patients with solid tumors. DESIGN AND METHODS: Fifty consecutive cancer patients with thrombocytopenia and/or leukopenia registered during a previous course of CT were randomized to receive, after the following course, IL-3 (10 microg/kg/day, s.c., day 1-5) followed by G- or GM-CSF (5 microg/kg/day, day 6-8). RESULTS: The nadir of WBC in the cycles supported with the combination of IL-3 and G-CSF was significantly higher than that observed in the CT cycles not supported by growth factors (p < 0. 005). Furthermore, severe leukopenia was abrogated in all the cycles supported with IL-3+G-CSF, while in the cycles without cytokines, this event was registered in 62.5% of the cases (p < 0.0005). Finally, the recovery of WBC was achieved a mean of 4 days earlier in the cycles supported with IL-3+G-CSF. As for thrombocytoprotection, no significant differences were evidenced, but severe thrombocytopenia was abrogated in all the cycles supported by IL-3+G-CSF (p < 0.05). Furthermore, platelet recovery after CT was achieved on average 3.5 days earlier in the IL-3+G-CSF group than in the previous cycles. The nadir of WBC count in the cycles supported by the combination of IL-3 and GM-CSF was significantly higher than that observed in the CT cycles not supported by growth factors (p < 0.005). Furthermore, severe leukopenia was abrogated in 40% of the cycles supported by IL-3+GM-CSF, while in the cycles without cytokines, this event was registered in 80% of the cases (p < 0.005). Finally, the recovery of WBC was achieved a mean of 3.5 days earlier in the cycles supported by IL-3+GM-CSF. As far as thrombocytoprotection is concerned, there were no significant differences in the nadir between the cycles supported by the association IL-3+GM-CSF and the cycles not supported by cytokines. However, severe thrombocytopenia was registered in 20% of the cycles not supported by growth factors but in only 10% of the cycles supported by IL-3+GM-CSF (p < 0.05). Furthermore, platelet recovery after CT was achieved on average 3 days earlier in the IL-3+GM-CSF group. The combination of IL-3 and G-CSF would appear to be more effective than the combination of IL-3 and GM-CSF in the control of both severe thrombocytopenia and leukopenia. Indeed, severe leukopenia was abrogated in all the cycles in arm A, but only in 40% of the cycles in arm B (p < 0.0005). Furthermore, considering a platelet count below 49     

Treatment of the anemia of myelodysplastic syndromes using recombinant human granulocyte colony-stimulating factor in combination with erythropoietin [see comments]

We treated myelodysplastic syndrome patients (MDS) with both recombinant human granulocyte colony-stimulating factor (G-CSF) and recombinant human erythropoietin (EPO) to determine whether such combination therapy resulted in improvement of their anemias. Twenty- four of 28 patients begun on study completed the protocol and were evaluable for erythroid responses. Therapy was initiated with G-CSF at 1 micrograms/kg administered by daily subcutaneous injection and adjusted to either normalize or double the neutrophil count. EPO was then administered by daily subcutaneous injection at a dose of 100 U/kg and dose-escalated to 150 and 300 U/kg every 4 weeks while continuing the G-CSF. Changes in absolute reticulocyte count, hematocrit level, and need for RBC transfusions were compared with pretreatment values as well as other blood cell counts. Ten of 24 patients (42%) had erythroid responses, whereas all patients had neutrophil responses. Six previously transfused patients no longer required RBC transfusions during the treatment period. Erythroid responses were found to be independent of patient age, French-American-British subtype, duration of disease, prior RBC transfusion requirements, or cytogenetic abnormalities at presentation. Pretreatment serum EPO levels were lower in erythroid-responding as compared with nonresponding patients (median 157 v 600 U/L; P = .05). The combined treatment modality was generally well tolerated. We conclude that a substantial percentage of MDS patients had both erythroid and myeloid responses when treated with the combination of G-CSF and EPO.     

Expansion of granulocyte colony-stimulating factor/chemotherapy-mobilized CD34+ hematopoietic progenitors: role of granulocyte-macrophage colony-stimulating factor/erythropoietin hybrid protein (MEN11303) and interleukin-15

Ex vivo stroma-free static liquid cultures of granulocyte colony-stimulating factor (G-CSF)/chemotherapy-mobilized CD34+ cells were established from patients with epithelial solid tumors. Different culture conditions were generated by adding G-CSF, granulocyte-macrophage colony-stimulating factor (GM-CSF), Flt3 ligand (Flt3), megakaryocyte growth and development factor (Peg-rHuMGDF), GM-CSF/erythropoietin (EPO) hybrid protein (MEN11303), and interleukin-15 (IL-15) to the basic stem cell factor (SCF) + interleukin-3 (IL-3) + EPO combination. This study showed that, among the nine different combinations tested in our 5% autologous plasma-containing cultures, only those containing IL-3/SCF/Flt3/MEN11303 and IL-3/SCF/Flt3/MEN11303/IL-15 significantly expanded colony-forming unit granulocyte-macrophage (CFU-GM), burst-forming unit erythroid (BFU-E), long-term culture-initiating cells (LTC-IC), CD34+, and CD34+/CD38- cells after 14 days of culture. Particularly, the addition of IL-15 to IL-3/SCF/Flt3/MEN11303 combination produced a significant increase of LTC-IC, with an average 26-fold amplification as compared to input cells, without any detrimental effect on CFU-GM and BFU-E expansion. This combination also produced a statistically significant 3.6-fold expansion of primitive CD34+/CD38- cells. Moreover, this study confirms the previously described erythropoietic effect of MEN11303, which, in our experience, was the only factor capable of expanding BFU-E. Compared to equimolar concentrations of GM-CSF and EPO, MEN11303 hybrid protein showed a significantly higher capacity of expanding CFU-GM, BFU-E, LTC-IC, CD34+, and CD34+/CD38- cells when these cytokines were tested in combination with IL-3/SCF/Flt3. These cultures indicated that Peg-rHuMGDF addition to IL-3/SCF/EPO/Flt3 does not affect CFU-GM and BFU-E expansion but, unlike G-CSF or GM-CSF, it does not decrease the ability of Flt3 to expand primitive LTC-IC. These studies indicate that, starting from G-CSF/chemotherapy-mobilized CD34+ cells, concomitant expansion of primitive LTC-IC, CFU-GM, BFU-E, CD34+, and CD34+/CD38- cells is feasible in simple stroma-free static liquid cultures, provided IL-3/SCF/Flt3/MEN11303/IL-15 combination is used as expanding cocktail in the presence of 5% autologous plasma.     

Clinical results of recombinant erythropoietin in transfusion-dependent patients with refractory multiple myeloma: role of cytokines and monitoring of erythropoiesis

Abstract: Recombinant erythropoietin (r-EPO) was administered to 37 patients with advanced, transfusion-dependent and chemo-resistant multiple myeloma (MM), at the fixed dose of 10,000/U s.c, 3 times a week, for 2 months. Thirteen patients (35.1%) achieved a significant response in terms of complete abolition of red cell transfusions. Factors significantly predictive of response were: a) inappropriate production of endogenous EPO, as expressed by a reduced observed/predicted ratio; b) presence of a consistant number of circulating erythroid precursors BFU–E; c) low serum levels of tumor necrosis factor (TNF) and interleukin-1 (IL-1), cytokines with inhibitory activity on erythropoiesis; d) a single line of previously received chemotherapy. Renal failure, bone marrow plasma cell infiltration, serum levels of IL-6 and other main clinical and laboratory parameters did not affect significantly the response to r-EPO. High fluorescence reticulocytes (HFR) and soluble transferrin receptor (sTfR) values were useful to detect an early stimulation of erythropoiesis in responders, while a high percentage of circulating hypochromic erythrocytes (HE), as assessed by an automated counter, identified those patients developing functional iron deficiency during r-EPO treatment. We conclude that about one-third of severely anemic patients with advanced MM, unresponsive to chemotherapy, may benefit by r-EPO therapy. The clinical management of these patients can be accomplished using non-invasive parameters, such as sTfR, HFR and HE.     

Erythropoietin plus granulocyte colony-stimulating factor is better than erythropoietin alone to treat anemia in low-risk myelodysplastic syndromes: results from a randomized single-centre study

Haemopoietic growth factors (HGF), i.e. erythropoietin [recombinant human erythropoietin (rHEPO)] or granulocyte colony stimulating factor (G-CSF), alone or in combination, have largely been used to treat anemia in myelodysplastic syndromes (MDS), but whether combined rHEPO and G-CSF is really superior to rHEPO alone is still under debate. In particular, randomized studies comparing front-line rHEPO vs rHEPO+G-CSF are still lacking. The aim of this study was to compare the effects of “standard” doses of rHEPO with the combination of rHEPO and G-CSF in the treatment of anemic patients with low-risk MDS in a prospective randomized trial. Anemic patients with low-risk MDS were randomly assigned to receive either rHEPO (10,000 IU s.c. three times a week) or the same dosage of rHEPO+G-CSF (300 μg s.c. twice a week) for a minimum of 8 weeks. Patients who were unresponsive to rHEPO were offered the combination therapy for another 8 weeks, whereas non-responders to rHEPO+G-CSF were considered “off study”. Responders continued the treatment indefinitely. Both haematological response and changes in quality-of-life (QoL) scores (Functional Assessment of Cancer Therapy-Anemia) were recorded and evaluated. Thirty consecutive patients [10 refractory anemia (RA), 5 RA with ringed sideroblasts, 7 refractory cytopenia with multilineage dysplasia, 5 RA with less than 10% blasts and 3 5q-syndrome] were enrolled in the study. All of them (15 in the rHEPO arm and 15 in the rHEPO+G-CSF arm) were valuable after the first 8 weeks of treatment. Erythroid response was observed in 6/15 (40%) patients in the rHEPO arm and in 11/15 (73.3%) patients in the rHEPO+G-CSF arm. In 4/9 (44.4%) patients who were unresponsive to rHEPO, the addition of G-CSF induced erythroid response at 16 weeks. No relevant adverse effects were recorded for either treatment in any of the study patients. Erythroid response to HGF was associated with a relevant improvement in QoL. Twenty responders continued the treatment. Afterwards, 8/20 (40%) discontinued therapy because of the following: losing response (2), progression to high-risk MDS (3) and death due to other causes (3). The remaining 12 are still responding and continuing treatment, with a median follow-up of 28 months. Progression to acute leukemia was cumulatively observed in 4/30 (13.3%) patients (2 in each arm). Although our data were obtained from a relatively small cohort of patients, they indicate that the rHEPO+G-CSF treatment is more effective than rHEPO alone for correcting anemia in low-risk MDS patients and for making a relevant improvement in their QoL.     

In vitro differentiation of human granulocyte/macrophage and erythroid progenitors: comparative analysis of the influence of recombinant human erythropoietin, G-CSF, GM-CSF, and IL-3 in serum-supplemented and serum- deprived cultures

The effects of recombinant human erythropoietin (Ep), granulocyte/macrophage (GM) and granulocyte (G) colony-stimulating factors (CSF), and interleukin-3 (IL-3) on erythroid burst and GM colony growth have been studied in fetal bovine serum (FBS)- supplemented and FBS-deprived culture. Sources of progenitor cells were nonadherent or nonadherent T-lymphocyte-depleted marrow or peripheral blood cells from normal humans. G-CSF, in concentrations up to 2.3 X 10(-10) mol/L, induced only the formation of neutrophil colonies. In contrast, GM-CSF and IL-3 both induced GM colonies and sustained the formation of erythroid bursts in the presence of Ep. However, the activities of these growth factors were affected by the culture conditions. IL-3 induction of GM colonies depended on the presence of FBS, whereas the degree of GM-CSF induction of GM colonies in FBS- deprived cultures depended on the method by which adherent cells were removed. GM-CSF increased colony numbers in a concentration-dependent manner only if the cells had been prepared by overnight adherence. Both GM-CSF and IL-3 exhibited erythroid burst-promoting activity in FBS- deprived cultures. However, some lineage restriction was evident because GM-CSF was two- to threefold more active than IL-3 in inducing GM colonies but IL-3 was two- to threefold more active in promoting erythroid burst growth. Furthermore, in FBS-deprived cultures, the number of both erythroid bursts and GM colonies reached the maximum only when Ep, GM-CSF, and IL-3 or GM-CSF, IL-3, and G-CSF, respectively, were added together. These results suggest that the colonies induced by IL-3, GM-CSF, and G-CSF are derived from different progenitors.     

Effects of recombinant human G-CSF, GM-CSF, IL-3, and IL-1 alpha on the growth of purified human peripheral blood progenitors.

The effects of recombinant products of granulocyte colony-stimulating factors (G-CSF), granulocyte/macrophage CSF (GM-CSF), human interleukin-3 (IL-3), and interleukin-1 (IL-1) were studied using purified target cell populations from patients undergoing peripheral blood stem cell transplantation after myeloablative therapy. Cells were subjected to combined purification procedures including negative selection with a panel of monoclonal antibodies (CD2, 3, 5, 10, and 20). The purified cells were enriched for HLA-DR+ (51% to 71%) and My-10+ (CD34; 37% to 54%) and had a plating efficiency of up to 20%. In the liquid-suspension limiting dilution clonal assay (LDA), purified progenitors responded directly to IL-3 by proliferation with single-hit kinetics. The ability of GM-CSF to support progenitor growth was inferior to that of IL-3, and the cells were virtually unresponsive when cultured with G-CSF, supporting the notion that these blood-derived progenitors belong to a primitive population of hematopoietic progenitor cells. The results obtained in simultaneous methycellulose cultures (MC) showed the same trend and provided additional information on the ability of GM-CSF and IL-3 to support erythroid progenitor growth. The combination of IL-3 plus G-CSF, but not IL-3 plus GM-CSF, resulted in a synergistic increase in colony number. IL-1 alpha increased both the size and number of colonies when added to IL-3 or G-CSF. Study of this enriched progenitor cell population in MC and LDA represents an excellent model for the investigation of myeloid and erythroid differentiation and for evaluating the influence of various cytokines on human hematopoiesis.     

Suppressed serum erythropoietin response to anemia and the efficacy of recombinant erythropoietin in the anemia of rheumatoid arthritis

Serum erythropoietin (EPO) was measured by radioimmunoassay in 67 patients with rheumatoid arthritis (RA). Twenty of these patients judged to have iron deficiency anemia, based on reduced serum ferritin levels, had higher serum EPO levels than did the 24 other anemic patients with normal or elevated serum ferritin levels. A significant negative correlation between serum EPO and hemoglobin concentrations was noted in the former group, but not in the latter. Human recombinant erythropoietin (r-EPO) was administered to 6 anemic patients with RA, resulting in improvement of anemia in 4 patients, 2 of whom showed no change in RA activity. These findings suggest a suppressed serum EPO response ot anemia and the effectiveness of r-EPO in treating anemia associated with RA.     

Maintenance treatment of the anemia of myelodysplastic syndromes with recombinant human granulocyte colony-stimulating factor and erythropoietin: evidence for in vivo synergy

Patients with myelodysplastic syndromes (MDS) have refractory cytopenias leading to transfusion requirements and infectious complications. In vitro marrow culture data have indicated that granulocyte colony stimulating factor (G-CSF) synergizes with erythropoietin (EPO) for the production of erythroid precursors. In an effort to treat the anemia and neutropenia in this disorder, MDS patients were treated with a combination of recombinant human EPO and recombinant human G-CSF. Fifty-five patients were enrolled in the study of which 53 (96%) had a neutrophil response. Forty-four patients were evaluable for an erythroid response of which 21 (48%) responded. An erythroid response was significantly more likely in those patients with relatively low serum EPO levels, higher absolute basal reticulocyte counts and normal cytogenetics at study entry. Seventeen (81%) of the patients who responded to combined G-CSF plus EPO therapy continued to respond during an 8-week maintenance phase. G-CSF was then discontinued and all patients' neutrophil responses were diminished, whereas 8 continued to have an erythroid response to EPO alone. In 7 of the remaining 9 patients, resumption of G-CSF was required for recurrent erythroid responses. The median duration of erythroid responses to these cytokines was 11 months, with 6 patients having relatively prolonged and durable responses for 15 to 36 months. Our results also indicate that approximately one half of responding patients require both G-CSF and EPO to maintain an effective erythroid response, suggesting that synergy between G-CSF and EPO exists in vivo for the production of red blood cells in MDS.     

Proliferation and differentiation of myelodysplastic CD34+ cells in serum-free medium: II. Response to combined colony-stimulating factors

Abstract: To investigate the role of colony stimulating factors (CSFs) in the proliferation and differentiation of progenitor cells from myelodysplastic syndromes (MDS), marrow progenitor cells from 18 MDS patients were highly purified using CD34 monoclonal antibody and immunomagnetic microspheres (MDS CD34+ cells). These cells were cultured in serum-free medium with various combinations of five colony stimulating factors (CSFs): recombinant human interleukin-3 (rIL-3), granulocyte/macrophage-CSF (rGM-CSF), granulocyte-CSF (rG-CSF), macrophage-CSF (rM-CSF), and erythropoietin (rEP). Among the tested CSFs, such as rM-CSF, rG-CSF, rGM-CSF and rIL-3, a combination of the first three CSFs was the most effective stimulus for the proliferation of non-erythroid MDS progenitor cells. An increase of undifferentiated “blast” cell colonies in 5/18 MDS patients occurred and these 5 patients belonged to the high-risk group. In the presence of these three CSFs, rIL-3 had no effect on the proliferation and differentiation of MDS CD34+ cells; however, IL-3 was efficient for the proliferation of MDS CD34+ cells to the erythroid lineage. rGM-CSF or rIL-3 alone did not efficiently support proliferation and differentiation of CD34+ cells. M-CSF is present in normal human serum at a concentration of 550 ±110 U/ml, a concentration exceeding that used in this study (100 U/ml). Therefore, in vivo administration of G-CSF combined with GM-CSF to MDS patients may be one of the most effective CSF combinations for proliferation of MDS progenitor cells to the non-erythroid lineage. However, the effect on the capacity for differentiation was minimal, especially in patients belonging to the high-risk group.     

Myeloid differentiation of purified CD34+ cells after stimulation with recombinant human granulocyte-monocyte colony-stimulating factor (CSF), granulocyte-CSF, monocyte-CSF, and interleukin-3.

CD34+ cells isolated from bone marrow or umbilical cord blood from healthy donors were studied for proliferation and differentiation in liquid cultures in the presence of recombinant human granulocyte-monocyte colony-stimulating factor (GM-CSF), granulocyte CSF (G-CSF), monocyte CSF (M-CSF), and interleukin-3 (IL-3), followed by immunophenotyping for myeloid and myeloid-associated cell surface markers. IL-3, either alone or together with GM-CSF, G-CSF, or M-CSF, induced, on average, 50-fold cell multiplication, GM-CSF five fold to 10-fold, and G-CSF and M-CSF less than fivefold. Cells from cultures stimulated with GM-CSF, G-CSF, or M-CSF alone contained cells with a "broad" myeloid profile, "broader" than observed in cultures with IL-3. However, since IL-3 induced rapid cell multiplication, high numbers of cells expressing early (CD13, CD33) and late myeloid markers (CD14, CD15) were recovered. The presence of other CSFs together with IL-3 did not alter the IL-3-induced effect on the cells. When 5,000 CD34+ cells were cultured with IL-3 alone, the cultures still contained 2,000 to 5,000 CD34+ cells after 14 days of culture, while cells cultured with GM-CSF, G-CSF, or M-CSF contained less than 1,000 CD34+ cells. Furthermore, 1,000 to 3,000 cells were positive for the megakaryocytic lineage marker CD41b after cultures with GM-CSF or IL-3, while cultures with G-CSF or M-CSF did not contain detectable numbers of CD41b+ cells. Finally, erythroid cells could also be generated from purified CD34+ cells. The results show that IL-3 and GM-CSF can induce rapid proliferation of purified CD34+ cells in vitro with differentiation to multiple myeloid lineages, while certain subsets maintain expression of CD34.     

Action of interleukin-3, G-CSF, and GM-CSF on highly enriched human hematopoietic progenitor cells: synergistic interaction of GM-CSF plus G-CSF

Purified preparations of recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte CSF (G-CSF), and interleukin 3 (IL-3 or multi-CSF) alone and in combination, have been compared for their stimulatory effects on human granulocyte-macrophage colony forming cells (GM-CFC). In cultures of unseparated normal human bone marrow, the combinations of G-CSF plus IL-3 and GM-CSF plus IL-3 stimulated additive numbers of GM colonies, while GM-CSF plus G-CSF stimulated greater than additive numbers of GM colonies, compared with the sum of the colony formation obtained with each factor alone. Cultures of unseparated bone marrow, harvested from patients four to six days after administration of 5-fluorouracil (5-FU), resulted in additive GM colony formation with GM-CSF plus G-CSF, GM-CSF plus IL-3, and G-CSF plus IL-3. In order to address the possibility of secondary factor involvement in the synergistic interaction of GM-CSF and G-CSF, CD33+/CD34+ colony forming cells were separated from normal and post FU marrow by two color fluorescence activated cell sorting. In cultures of CD33+/CD34+ cells the combination of GM-CSF plus G-CSF stimulated a synergistic increase in GM colonies while GM-CSF plus IL-3 stimulated additive numbers of colonies. These results suggest that GM-CSF, G-CSF, and IL-3 stimulate distinct populations of GM-CFC. Furthermore GM-CSF and G-CSF interact synergistically and this action is a direct effect on progenitor cells not stimulated by GM-CSF or G-CSF alone.     

Role of cytokines in leukemic type growth of myelodysplastic CD34+ cells

The clonal growth of progenitor cells from myelodysplastic syndromes (MDS) can be subdivided into four growth patterns: (1) normal, (2) no growth or low plating efficiency, (3) low colony and high cluster number, and (4) normal or high colony number with a large number of clusters. The former two (1 and 2) can be referred to as nonleukemic patterns and latter two (3 and 4) as leukemic. In a search for a role for cytokines in leukemic-type growth of MDS progenitor cells, marrow CD34+ cells were purified up to 94% for 8 normal individuals and 88% for 12 MDS patients, using monoclonal antibodies and immunomagnetic microspheres (MDS CD34+ cells). The purified CD34+ cells were cultured for 14 days with various combinations of cytokines, including recombinant human macrophage colony-stimulating factor (rM-CSF), granulocyte-CSF (rG-CSF), granulocyte-macrophage-CSF (rGM-CSF), interleukin-3 (rIL-3), and stem cell factor (SCF; a ligand for c-kit) in serum-free medium. The clonal growth of MDS CD34+ cells supported by a combination of all of the above cytokines was subdivided into the two patterns of leukemic or nonleukemic, and then the role of individual or combined cytokines in proliferation and differentiation of MDS CD34+ cells was analyzed in each group. Evidence we obtained showed that SCF plays a central role in the leukemic-type growth of MDS CD34+ cells and that G-CSF, GM-CSF; and/or IL-3 synergize with SCF to increase undifferentiated blast cell colonies and clusters over that seen in normal CD34+ cells. SCF is present in either normal or MDS plasma at a level of nanograms per milliliter, and this physiologic concentration of SCF can stimulate progenitor cells. This means that progenitor cells are continuously exposed to stimulation by SCF in vivo and that MDS leukemic cells have a growth advantage over normal blast cells. This depends, at least in part, on cytokines such as G-CSF, GM-CSF, IL-3, and SCF.