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Results for “Granulocyte Precursor Cells”

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PubMed1995

Changes in erythroid progenitor cell and accessory cell compartments in patients with myelodysplastic syndromes during treatment with all-trans retinoic acid and haemopoietic growth factors.

Differentiation induction therapy is used in myelodysplastic syndromes (MDS) to improve maturation defects and to restore impaired function of malignant cells. To this end, 18 patients with MDS received either a combination therapy consisting in study 1 of all-trans retinoic acid (ATRA) and granulocyte-colony stimulating factor (G-CSF), or in study 2 of a combination with ATRA, G-CSF, erythropoietin (Epo) and tocopherol. The ANC increased in 19/20 patients in both studies, whereas an increase in haemoglobin concentration, platelet counts or reduction of transfusion requirement was seen in only 8/20 patients, correlating strongly with good BFU-E growth (P < 0.001). To assess the role of accessory cells in the modulation of the haemopoietic response to treatment, we analysed the capacity of peripheral blood monocytes to secrete cytokines (IL-1 beta, IL-6, IL-8, TNF alpha). Secretion of all cytokines was significantly reduced before therapy when compared with healthy controls, but increased during therapy, reaching normal levels for IL-8. These data indicate that a combination therapy with ATRA and cytokines improves impaired cytokine secretion from monocytes and induces a multilineage clinical response in a subgroup of MDS patients characterized by an almost intact erythroid compartment. In contrast, induction of TNF alpha might be responsible for treatment failure.

Adult↗

PubMed2002

Influence of lineage-specific cytokines on commitment and asymmetric cell division of haematopoietic progenitor cells.

We examined the influence of cytokines on erythroid- and myeloid-lineage development of AC133+ cells during primary and secondary cultures. Cells cultured for 14 d in liquid medium containing erythropoietin (EPO) were amplified 831-fold with 98.2% erythroid cells. A similar culture exposed to granulocyte colony-stimulating factor (G-CSF) grew 1350-fold with 97.4% myeloid cells. To assess whether the cells with EPO inducement could respond at this point to G-CSF signal, or vice versa, the EPO-stimulated population was re-grown with G-CSF, constituting 95.2% myeloid, of 5075-fold, cells after 14 d of re-culture. Conversely, reculture of the G-CSF-stimulated population with EPO resulted in a 4083-fold growth with 81.4% erythroid cells. Semisolid culture containing EPO orG-CSF showed that some individual colonies had self- renewal potential after 14 d culture and could be induced todevelop into a different lineage. Analysis of primitive markers, CD34 and Notch1, or lineage markers, EPO-R and CD13, by single-cell reverse transcription polymerase chain reaction showed that individual colonies of 2-16 cells contained at least one CD34-positive cell with expression ofNotch1 and co-expression of EPO-R and CD13 appeared on either CD34-positive or CD34-negative cells. In situ hybridization with the same cell surface markers in cell populations confirmed the asymmetric cell division and co-expression from single cell data. The study provides a useful model for the analysis of multipotential progenitor development, and indicates that progenitor cells co-express genes from different lineage pathways before commitment and that cytokines influence lineage commitment.

AC133 Antigen↗

PubMed2002

Vasoactive intestinal peptide (VIP) inhibits the proliferation of bone marrow progenitors through the VPAC1 receptor.

OBJECTIVE: The cellular and molecular mechanisms of hematopoietic stimulation have been studied. However, an understanding of negative effects in the hematopoietic system remains elusive. To this end, we studied the effects of vasoactive intestinal peptide (VIP) on bone marrow (BM) progenitors. MATERIALS AND METHODS: Different BM cell subsets were used to perform clonogenic assay for granulocytic (CFU-GM) or erythroid (BFU-E and CFU-E) progenitors with 10(-7)-10(-13) M VIP. The relevant receptor was verified with specific antagonists, or agonists, semi-quantitative RT-PCR, and chemical cross-linking studies with stromal membranes. RESULTS: Assays performed with unfractionated mononuclear cells and enriched CD34(+) cells showed dose-dependent inhibition on BM progenitors with significant inhibition up to 10(-10) M. Nylon wool separated cells, which depleted stroma, reversed the inhibitory effects of VIP between 10 and 20%. Combined experimental evaluation indicated that the effects of VIP on BM functions are mediated through the type 1 receptor (VPAC1). VIP induced the production of TGF-beta and TNF-alpha in BM mononuclear cells and stroma. These cytokines are partly involved in reversing the suppressive effects of VIP on CFU-GM. CONCLUSIONS: The effect of VIP on BM progenitors could be mediated through direct and indirect mechanism. Direct effects were evident by the suppressive effects of VIP on clonogenic assays with highly purified CD34(+) cells. Indirect effects were mediated through putative functions of the stromal cells and the production of TGF-beta and TNF-alpha.

Adult↗

PubMed1978

Increased granulocytic, erythrocytic, and megakaryocytic progenitors in myelofibrosis with myeloid metaplasia.

Nucleated cells obtained from blood and/or bone marrow of patients with myelofibrosis with myeloid metaplasia (MMM) were cultured in diffusion chambers (DC) implanted into the peritoneal cavities of irradiated mice. A total of five blood studies and two bone marrow studies were performed using cells obtained from five patients. The DC were harvested at intervals from the host mice and the total and differential cellularity of DC contents were evaluated. The results obtained from MMM cultures were compared with those from similar cultures of blood cells and marrow cells of four and six normal individuals respectively. The proliferation and maturation of the granulocytic, erythrocytic, and megakaryocytic lines in MMM cultures occurred in an orderly fashion as they occur in vivo. The patterns of proliferation and maturation of the three cell lines in cultures after day 7 suggest that they primarily originate from progenitor cells. The numbers of granulocytes in the multiplicative pool, recognizable red cell precursors, and megakaryocytes recovered were significantly greater from the MMM cultures than those from the normal blood or marrow cultures. These results suggest that the blood and marrow cells of MMM patients have increased numbers of progenitors for granulocytes, erythrocytes, and megakaryocytes.

Adult↗

PubMed2004

GM-CSF Biology.

Granulocyte macrophage-colony stimulating factor (GM-CSF) was originally defined by its ability to generate in vitro granulocyte and macrophage colonies from bone marrow precursor cells. Apart from its physiological role in the control of alveolar macrophage development, it now appears more likely that its major role lies in its ability to govern the properties of the more mature myeloid cells of the granulocyte and macrophage lineages, particularly during host defence and inflammatory reactions. This review summarizes the in vivo evidence to support this proposition. This evidence includes both the findings obtained by administration of GM-CSF, e.g. as an adjuvant, and also includes those observed in depletion studies, e.g. during inflammatory reactions where GM-CSF can be shown to have a proinflammatory action.

Animals↗

PubMed2005

Functions of granulocyte-macrophage colony-stimulating factor.

GM-CSF was originally defined by its ability to generate in vitro granulocyte and macrophage colonies from bone marrow precursor cells. Apart from its physiological role in the control of alveolar macrophage development, it now appears more likely that its major role lies in its ability to govern the properties of the more mature myeloid cells of the granulocyte and macrophage lineages, particularly during host defence and inflammatory reactions. Recent evidence is summarized below for a key role for GM-CSF in inflammatory and autoimmune diseases, making it therefore worthy of consideration for targeting. Such evidence includes disease exacerbation following its administration and amelioration of disease in animal models by GM-CSF gene targeting or by anti-GM-CSF antibody blockade. This review summarizes the evidence supporting a major role for GM-CSF in inflammation and autoimmunity and its functions as major regulator governing granulocyte and macrophage lineage populations at all stages of maturation.

Animals↗

PubMed1994

Pilot trial of combined administration of erythropoietin and granulocyte colony-stimulating factor to children undergoing allogeneic bone marrow transplantation.

We carried out a pilot study to evaluate the combined use of recombinant human erythropoietin (rhEpo) and granulocyte colony-stimulating factor (G-CSF) for accelerating marrow engraftment in children given allogeneic bone marrow transplantation (BMT). Fifteen consecutive children were enrolled in this study; 13 completed it and were evaluable. Using analysis of variance, laboratory and clinical data referring to these children were compared with those of 15 patients previously treated with rhEpo alone and with those of 16 historical controls. Erythroid repopulation, evaluated sequentially through serum transferrin receptor and reticulocyte count, was similarly accelerated in children receiving rhEpo alone and in those receiving combined treatment. These latter, however, showed a further reduction in the total number of red blood cell units required to reach transfusion independence (1.1 +/- 0.7 in the study population vs 2.7 +/- 1.2 in rhEpo group vs 4.2 +/- 2.3 in historical controls; values are mean +/- 1 SD; p < 0.001). Neutrophil engraftment, i.e. time for neutrophils to reach 0.5 x 10(9)/l, was 11 +/- 3 days in children receiving combined treatment, significantly shorter than that of the control groups (16 +/- 3 and 18 +/- 5, respectively; p < 0.001). Acceleration of neutrophil recovery translated into fewer infections: days of fever were significantly reduced in the study population (4 +/- 2 vs 11 +/- 8 vs 15 +/- 6, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed2001

Biological significance of MAPK, AKT and JAK-STAT protein activation by various erythropoietic factors in normal human early erythroid cells.

The aim of this study was to identify signal transduction pathways activated by erythropoietin (EpO) and erythropoietin co-stimulatory factors (kit ligand), insulin-like growth factor, thrombopoietin, interleukin 3 and granulocyte-macrophage colony-stimulating factor) in normal human bone marrow CD34(+) cells and d 11 erythroid burst forming unit derived glycophorin+ cells. The activation of these signal transduction pathways was further correlated with various biological effects such as (i) cell proliferation, (ii) inhibition of apoptosis, (iii) activation of adhesion and (iv) secretion of the matrix metalloproteinases (MMPs) MMP-9 and MMP-2, and vascular endothelial growth factor (VEGF). We found that in human CD34(+) cells and erythroblasts erythropoietic factors may activate similar but different signalling pathways, and that activation of each of the JAK-STAT, MAPK p42/44 or PI-3K-AKT axes alone is not sufficient either to stimulate cell proliferation or inhibit apoptosis, suggesting that these processes are regulated by orchestrated activation of multiple signalling cascades. Accordingly, we found that although cell proliferation was more related to simultaneous activation of JAK-STAT and MAPK p42/44, the effect on cell survival correlated with activation of PI-3K-AKT, MAPK p42/44 and JAK-STAT proteins. We also demonstrated that differentiating normal human erythroid cells lose their adhesive properties and secrete angiopoietic factors such as MMP-9, MMP-2 and VEGF, and we postulate that this secretion by early erythroid cells may play a role in their maturation and egress from the haematopoietic niches of the bone marrow.

Antigens, CD34↗

PubMedDate not supplied

High-dose cyclophosphamide followed by GM-CSF is a safe and effective procedure for the recruitment of trilineage circulating progenitor cells.

BACKGROUND: Several methods for the recruitment of circulating progenitor cells (CPC) to be used for hemopoietic rescue after myeloablative therapy have been described. The present study was designed to verify the effectiveness and safeness of one of such procedures, involving the administration of high-dose cyclophosphamide (HD-CTX) and granulocyte-macrophage colony-stimulating factor (GM-CSF). METHODS: Eight tumor patients were treated with HD-CTX (7 g/m2), followed by GM-CSF (7 mcg/Kg/day, continuous infusion) from day +2 to the completion of leukocyte recovery, when aphereses for CPC harvesting were performed. CPC were evaluated by clonogenic assay for granulocyte-macrophage colony-forming units (CFU-GM), megakaryocyte colony-forming units (CFU-Meg) and erythrocyte burst-forming units (BFU-E) before therapy as well as during the hemopoietic recovery. RESULTS: In each patient, a significant increase of trilineage CPC was observed, at a mean of 14 days from HD-CTX, with peak increment of 224, 268 and 230-fold for CFU-GM, CFU-Meg and BFU-E respectively. The mean duration of leukocyte count < or = 0.5 x 10(9)/l was 6.6 days, with severe thrombocytopenia (grade 4 WHO) lasting 2.8 days in 5 patients. GM-CSF infusion was well tolerated without any need for dose reduction or discontinuation. CONCLUSION: The administration of HD-CTX and GM-CSF induces a significant enhancement of CPC including CFU-Meg other than CFU-GM and BFU-E. The procedure is suitable for the recruitment of CPC in patients with CTX sensitive tumors.

Adult↗

PubMed1993

Activin A suppresses proliferation of interleukin-3-responsive granulocyte-macrophage colony-forming progenitors and stimulates proliferation and differentiation of interleukin-3-responsive erythroid burst-forming progenitors in the peripheral blood.

We examined the effects of activin A on the proliferation and differentiation of immature hematopoietic progenitors prepared from peripheral blood (PB) using methylcellulose and liquid-suspension culture. In a kinetic analysis, colony formation by PB granulocyte-macrophage colony-forming unit (CFU-GM) was delayed in a dose-dependent manner by the addition of activin A only when stimulated with interleukin-3 (IL-3), but not when stimulated with granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), or stem cell factor (SCF) plus G-CSF. DNA-synthesizing CFU-GM was increased by IL-3, but this effect was abolished by activin A. In contrast, PB erythroid burst-forming unit (BFU-E) was accelerated by the addition of activin A only when exposed to IL-3 plus erythropoietin (Epo), but not when exposed to Epo or Epo plus SCF. DNA-synthesizing BFU-E was increased by IL-3 and activin A, alone and additively in combination. In a mixed culture of myeloid and erythroid progenitors, activin A increased the numbers of BFU-E and CFU-Mix colonies at concentrations of 1 and 10 ng/mL and decreased the number of CFU-GM colonies in a dose-dependent manner. However, in a liquid-suspension culture of erythroid progenitors, activin A decreased total cell count and the percentage of hemoglobin-containing cells only when cells were exposed to IL-3 plus Epo. These results indicate that activin A suppresses the proliferation of IL-3-responsive CFU-GM progenitors and stimulates the proliferation and differentiation of IL-3-responsive BFU-E progenitors, and suggest that activin A acts as a commitment factor of immature hematopoietic progenitors for erythroid differentiation.

Activins↗

PubMed1995

In vitro and in vivo myelotoxicity of CAI to human and murine hematopoietic progenitor cells.

Carboxyamido-triazole (CAI), an agent that targets calcium-sensitive signal transduction pathways, has both antiproliferative and antimetastatic properties. The objective of this study was to evaluate the myelotoxicity of CAI to normal human and murine hematopoietic cells. In vitro toxicity of CAI was determined by inhibition of myeloid [colony-forming unit-granulocyte/macrophage (CFU-gm)] and erythroid [burst-forming unit-erythroid (BFU-e)] colony formation in clonal assays. The effects of oral CAI on CD2F1 mouse marrow and splenic cellularity, marrow progenitor content, and peripheral blood cell counts were assessed in relation to plasma CAI levels. In vitro, CAI caused a concentration-dependent inhibition of CFU-gm and BFU-e colonies following continuous drug exposure. Murine CFU-gm and BFU-e were inhibited > 90% by 10 and 15 micrograms/mL CAI, respectively. However, suppression of human CFU-gm and BFU-e did not exceed 65% at the same concentrations. In vivo, CAI reduced the number of CFU-gm and BFU-e per femur after the initial dose and through day 4. Variations in colony inhibition paralleled changes in CAI plasma concentrations. While colony inhibition increased in vitro with escalating drug concentrations, this was not observed in vivo with additional CAI doses. The low toxicity of CAI in vivo combined with the significant difference between toxicity for human and mouse progenitors in vitro suggests a relatively low adverse potential to the bone marrow for this new signal transduction inhibitory agent.

Animals↗

PubMed1994

Glycosylation of recombinant human granulocyte colony stimulating factor: implications for stability and potency.

The production of recombinant human granulocyte colony stimulating factor (HuG-CSF) by gene cloning has made this growth factor available in large quantities for clinical application. There is accumulating evidence to suggest that the glycosylation of HuG-CSF confers advantages in terms of in vitro stability to temperature, pH and degradation by proteases, and a recent report attributes a greater biological potency, in the absence of larger biological mass, to the property of glycosylation. In this study, the biological potency of glycosylated rHuG-CSF (lenograstim) was compared with that of non-glycosylated rmetHuG-CSF (filgrastim) and a non-glycosylated rHuG-CSF (non-commercial preparation), using duplicate assays of neutrophil and erythroid colony formation in three human bone marrows. Serial doubling dilutions of each rHuG-CSF resulted in a concentration range of 0.008-128 ng/ml. Qualitative (number) and quantitative (size) assessments of colonies were performed at day 14 of culture. Lenograstim proved twice as potent as filgrastim (and non-commercial rHuG-CSF) at maximal colony stimulation, and 20 times more potent than both at half-maximal colony stimulation (P = 0.0001). Incubation with lenograstim also produced a higher proportion of colonies with > 200 cells than either of the other preparations. In conclusion, glycosylated rHuG-CSF (lenograstim) had a greater qualitative and quantitative potency than the non-glycosylated rHuG-CSFs (filgrastim and non-commercial rHuG-CSF), indicating that glycosylation confers a potency advantage on lenograstim.

Colony-Forming Units Assay↗

PubMed1979

Evidence for a rat granulocyte chalone effect on the proliferation of normal human bone marrow and of myeloid leukemias.

Evidence is presented that rat ascites cell extracts, acting as granulocyte chalone, temporarily inhibit the cell doubling of granulocytopoietic precursors in suspension cultures of human bone marrow. The extracts do not affect the proliferation of erythroblasts and do not show any cytotoxicity. In addition, a relative increase of granulocytic precursors capable of proliferation was found, suggesting an increase in the resting population of the granulocytopoietic proliferation pool due to extract treatment. However, the extract capable of depressing the proliferation of the normal granulocytopoiesis did not affect the granulocytopoiesis of 7 chronic myeloid and 2 chronic myelomonocytic leukemias at the same dose level. In contrast to these chronic leukemias, blast proliferation of 4 acute myeloid and monocytic leukemias was greatly depressed not only for 6 h but for the whole culture period of 48 h.

Animals↗

PubMed1994

c-kit is expressed by primitive human hematopoietic cells that give rise to colony-forming cells in stroma-dependent or cytokine-supplemented culture.

Using monoclonal antibody (MAB) YB5.B8, we have examined the expression of the c-kit protein, the receptor for the hematopoietic cytokine stem cell factor (SCF), on primitive hematopoietic cells. Bone marrow mononuclear cells (BMMNC) enriched for immature cells by differential agglutination using the lectin soybean agglutinin (SBA) were subjected to multiparameter fluorescence activated cell sorting (FACS) based on light-scattering properties, the expression of the c-kit protein and the CD34 antigen, and the retention of the vital fluorescent dye, Rhodamine 123 (Rh123). Sorted populations were assayed for their content of directly clonogenic progenitor cells (colony-forming units-granulocyte/macrophage [CFU-GM], burst-forming units-erythroid [BFU-E], and multipotential colony-forming units [CFU-Mix]) and for the presence of more primitive progenitor cells ("pre-CFU"). The latter were assayed by (1) their ability to initiate and sustain hematopoiesis in a standard stromal cell-dependent culture system and (2) their capacity for de novo generation of clonogenic progenitors in response to a combination of six recombinant hematopoietic cytokines in a stroma-independent suspension culture assay. A mean of 76% of CD34+ cells were found to coexpress c-kit. The majority of directly clonogenic cells (98% of CFU-GM, 98% of CFU-Mix, and 85% of BFU-E) were found in the CD34+c-kit+ fraction. Similarly, all pre-CFU were recovered in the CD34+c-kit+Rh123dull fraction, irrespective of whether the cells were maintained on marrow stromal cells or in cytokine-supplemented liquid culture. A mean of 87% (range 70-100%) of the CD34+Rh123dull cells also expressed c-kit. Since SCF has been reported to act as a growth factor for early lymphoid cells as well as myeloid cells, we looked for coexpression of c-kit and early lymphoid markers in the CD34+ population by multiparameter flow cytometry. Coexpression of c-kit on a minority of cells with markers of B or T lineages was observed. The majority of early lymphoid cells, however, appeared to lack c-kit expression. This was confirmed by the finding that only 4% of c-kit+CD34+ cells showed terminal deoxynucleotidyl transferase (TdT) activity, compared with 25% of the c-kit-CD34+ cells.

Antigens, CD↗

PubMed1992

Thymic humoral factor-gamma 2, an immunoregulatory peptide, enhances human hematopoietic progenitor cell growth.

Thymus humoral factor-gamma 2 (THF gamma 2), an octapeptide important for T-lymphocyte regulation, was assessed for its effect on the in vitro growth of human hematopoietic progenitor cells. This was achieved using a recombinant granulocyte-macrophage colony-stimulating factor (rGM-CSF)-stimulated myeloid cell colony formation (granulocyte-macrophage colony-forming cells, GM-CFC) assay as well as a recombinant erythropoietin (rEpo)-stimulated erythroid burst formation (erythroid burst-forming units, BFU-E) assay. Cells were obtained from bone marrow (BM) and peripheral blood (PB) of normal healthy donors and from patients with suppressed bone marrows. The latter group included aplastic anemia, leukemia, and lymphoma patients and patients with solid tumors who responded to intensive chemotherapy with significant pancytopenia. THF gamma 2 significantly enhanced normal BM and PB GM-CFC and PB BFU-E by 2- to 2.5-fold. This effect was totally dependent on the presence of the respective growth factors, that is, rGM-CSF or rEpo, and was specifically reversed by an anti-THF gamma 2 antiserum. Furthermore, although THF gamma 2-induced enhancement of GM-CFC colony formation was not affected by lymphocyte or monocyte depletion, the augmenting effect of the peptide on BFU-E was completely abrogated in the absence of lymphocytes. THF gamma 2-induced augmented growth of progenitor cells derived from severely suppressed marrows was minimal. However, cells from moderately neutropenic patients with leukemia in remission or with lymphoma under chemotherapy responded to the peptide similarly to cells from normal donors. These results suggest a stimulatory role for THF gamma 2 on human myeloid and erythroid hematopoietic progenitor cells. They also suggest the lymphocyte dependence of BFU-E enhancement and lymphocyte independence of GM-CFC stimulation by THF gamma 2. In the former case the thymus-derived peptide may act through the induction of certain erythroid-enhancing lymphokines.

Adjuvants, Immunologic↗

PubMed1995

Interferon-gamma exerts its negative regulatory effect primarily on the earliest stages of murine erythroid progenitor cell development.

Interferon-gamma (INF-gamma) has been shown to suppress erythropoiesis and perhaps to contribute to the anemia of chronic disease. In this study we demonstrated that the concentration of INF gamma required to suppress murine burst forming unit-erythroid (BFU-E) growth was significantly less than that required to suppress colony forming unit-erythroid (CFU-E) growth. INF gamma acted at the most primitive step in erythroid progenitor cell differentiation and proliferation, as inhibition was maximal when added at the time of BFU-E culture initiation. Inhibition was progressively less if INF gamma addition was delayed after culture initiation. The effects of INF gamma on BFU-E did not require the presence of interleukin-1 alpha (IL-1 alpha), tumor necrosis factor-alpha (TNF alpha), or granulocyte macrophage colony stimulating factor (GM-CSF), as its effects were not neutralized by monoclonal antibodies against IL-1 alpha, TNF alpha, or GM-CSF. This applied whether INF gamma was added to culture with individual antibodies or with a combination of all three antibodies. INF gamma was not required for IL-1 alpha- or TNF alpha-induced suppression of BFU-E, as their effects were not neutralized by a monoclonal anti-INF gamma antibody. In contrast, GM-CSF-induced suppression of BFU-E was negated by the simultaneous addition of anti-INF gamma. We have previously shown that the addition of TNF alpha does not suppress BFU-E growth in cultures from marrow depleted of macrophages. Suppression did occur, however, if a small concentration of INF gamma that does not inhibit and increasing concentration of TNF alpha were added to culture, suggesting a synergistic effect between INF-gamma and TNF alpha. These observations suggest that INF gamma is a potent direct inhibitor of erythroid colony growth in vitro. It exerts its negative regulatory effect primarily on the earliest stages of erythroid progenitor cell differentiation and proliferation, as much higher doses are required to suppress late erythroid cell development. INF gamma is also involved in GM-CSF-induced inhibition of BFU-E colony growth.

Animals↗

PubMed1992

Long-term recombinant human granulocyte colony-stimulating factor (rhG-CSF) treatment severely depresses murine marrow erythropoiesis without causing an anemia.

We hereby report profound effects of long-term granulocyte colony-stimulating factor (G-CSF) administration on murine erythropoiesis. Recombinant human (rh)G-CSF (150 micrograms/kg body weight/day) was administered over 24 days to female C57Bl mice. Marrow erythroid colony-forming units (CFU-E) and erythroblast numbers declined to less than 5% of normal, whereas splenic erythropoiesis simultaneously increased. Splenic erythropoiesis effectively compensated for the loss of marrow erythropoiesis as indicated by the maintenance of a normal hematocrit. In the marrow the numbers of spleen colony-forming units (CFU-S) and erythroid burst-forming units (BFU-E) declined as well. Simultaneously, however, these numbers increased both in the spleen and in the peripheral blood by a factor of 20 to 30. These findings suggest a continuous migration of stem cells and progenitor cells out of the marrow and an efficient seeding in the spleen, directly or indirectly induced by G-CSF. In addition the differentiation and/or amplification of BFU-E to CFU-E was impaired in the marrow but not in the spleen. The marrow and splenic microenvironment also behaved differently with respect to granulopoiesis. G-CSF did not lead to an enhanced granuloid amplification in the spleen but exerted its proliferation activity mainly in the marrow. These findings imply that prolonged G-CSF treatment might cause erythroid depression in animals and humans when spleen erythropoiesis is less efficient than in mice.

Anemia↗

PubMed1994

Prevention of hematopoietic myeloid and megakaryocyte toxicity associated with zidovudine in vivo in mice with recombinant GM-CSF.

We studied the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on the suppression of hematopoiesis associated with the use of the antiviral drug zidovudine (AZT) administered in vivo to normal mice, as determined by measuring peripheral blood indices, and assays of hematopoietic progenitors, i.e. erythroid (CFU-E/BFU-E), myeloid (CFU-GM), and megakaryocyte (CFU-Meg) from bone marrow and spleen. Previous studies from this laboratory have established that dose-escalation zidovudine induced a dose-dependent decrease in hematocrit, WBC, and platelets with altered populations of bone marrow and splenic erythroid, myeloid and megakaryocyte progenitors when administered to normal mice. Daily administration of GM-CSF (10 micrograms/kg/bw) was associated with altered peripheral blood indices and progenitor cells. Dose-escalation AZT, i.e. 0.1, 1.0 and 2.5 mg/ml, was associated with a comparable reduction in all indices, i.e. hematocrit, WBC, and platelets during the 6-week examination period. GM-CSF reduced zidovudine-induced myeloid toxicity (concentration < 2.5 mg/ml) which was associated with an increase in bone marrow and splenic CFU-GM. High concentration, i.e. 2.5 mg/ml still produced myelosuppression irreversible with GM-CSF. GM-CSF induced a reduction in circulating platelets following zidovudine treatment at weeks 2 and 4 with the 1.0 mg/ml and 2.5 mg/ml treatment groups respectively, compared to a persistent decrease in platelets in the presence of zidovudine alone. GM-CSF BFU-E were elevated indicating the restriction in erythoid differentiation was still present. These studies demonstrate GM-CSF influences myeloid and megakaryocyte recovery, but not the erythoid suppression associated with the antiviral drug zidovudine.

Animals↗