Effects of interleukin-6 and granulocyte colony-stimulating factor on the proliferation of leukemic blast progenitors from acute myeloblastic leukemia patients

Bone marrow inflammation in haematological malignancies

Tissue inflammation is a hallmark of tumour microenvironments. In the bone marrow, tumour-associated inflammation impacts normal niches for haematopoietic progenitor cells and mature immune cells and supports the outgrowth and survival of malignant cells residing in these niche compartments. This Review provides an overview of our current understanding of inflammatory changes in the bone marrow microenvironment of myeloid and lymphoid malignancies, using acute myeloid leukaemia and multiple myeloma as examples and highlights unique and shared features of inflammation in niches for progenitor cells and plasma cells. Importantly, inflammation exerts profoundly different effects on normal bone marrow niches in these malignancies, and we provide context for possible drivers of these divergent effects. We explore the role of tumour cells in inflammatory changes, as well as the role of cellular constituents of normal bone marrow niches, including myeloid cells and stromal cells. Integrating knowledge of disease-specific dynamics of malignancy-associated bone marrow inflammation will provide a necessary framework for future targeting of these processes to improve patient outcome.

Cerebrospinal fluid interleukin-6 is a potential diagnostic biomarker for central nervous system involvement in adult acute myeloid leukemia

Objective

We evaluated the correlation between cerebrospinal fluid (CSF) cytokine levels and central nervous system (CNS) involvement in adult acute myeloid leukemia (AML).

Methods

The study sample consisted of 90 patients diagnosed with AML and 20 with unrelated CNS involvement. The AML group was divided into two sub-groups: those with (CNS+, n=30) and without CNS involvement (CNS-, n=60). We used a cytometric bead assay to measure CSF interleukin (IL)-2, IL-4, IL-6, and IL-10, tumor necrosis factor-α, interferon-γ, and IL-17A. We used receiver operating characteristic curves to evaluate the ability of CSF cytokine levels to identify CNS involvement in adult AML.

Results

CSF IL-6 levels were significantly higher in CNS+adult AML patients and positively correlated with the lactate dehydrogenase levels (r=0.738, p<0.001) and white blood cell (WBC) count (r=0.455, p=0.012) in the blood, and the protein (r=0.686, p<0.001) as well as WBC count in the CSF (r=0.427, p=0.019). Using a CSF IL-6 cut-off value of 8.27 pg/ml yielded a diagnostic sensitivity and specificity was 80.00% and 88.46%, respectively (AUC, 0.8923; 95% CI, 0.8168–0.9678). After treating a subset of tested patients, their CSF IL-6 levels decreased. Consequently, the elevated CSF IL-6 levels remaining in CNS+ adult AML patients post-treatment were associated with disease progression.

Conclusion

CSF IL-6 is a promising marker for the diagnosis of adult AML with CNS involvement and a crucial dynamic indicator for therapeutic response.

The cytokine network in acute myeloid leukemia

Acute myeloid leukemia (AML) is a highly heterogeneous malignancy of the blood and bone marrow, characterized by clonal expansion of myeloid stem and progenitor cells and rapid disease progression. Chemotherapy has been the first-line treatment for AML for more than 30 years. Application of recent high-throughput next-generation sequencing technologies has revealed significant molecular heterogeneity to AML, which in turn has motivated efforts to develop new, targeted therapies. However, due to the high complexity of this disease, including multiple driver mutations and the coexistence of multiple competing tumorigenic clones, the successful incorporation of these new agents into clinical practice remains challenging. These continuing difficulties call for the identification of innovative therapeutic approaches that are effective for a larger cohort of AML patients. Recent studies suggest that chronic immune stimulation and aberrant cytokine signaling act as triggers for AML initiation and progression, facets of the disease which might be exploited as promising targets in AML treatment. However, despite the greater appreciation of cytokine profiles in AML, the exact functions of cytokines in AML pathogenesis are not fully understood. Therefore, unravelling the molecular basis of the complex cytokine networks in AML is a prerequisite to develop new therapeutic alternatives based on targeting cytokines and their receptors.

Antibiotic and glucocorticoid-induced recapitulated hematological remission in acute myeloid leukemia: A case report and review of literature

BACKGROUND

Leukemic hematopoietic cells acquire enhanced self-renewal capacity and impaired differentiation. The emergence of symptomatic leukemia also requires the acquisition of a clonal proliferative advantage. Untreated leukemia patients usually experience an aggressive process. However, spontaneous remission occasionally occurs in patients with acute myeloid leukemia (AML), most frequently after recovery from a febrile episode, and this is generally attributed to the triggering of antineoplastic immunity. There may be another explanation for the spontaneous remission as implicated in this paper.

CASE SUMMARY

A 63-year-old Chinese man presented with high fever, abdominal pain and urticaria-like skin lesions. He was diagnosed with AML-M4 with t(8;21) (q22;q22)/RUNX1-RUNX1T1 based on morphological, immunological, cytogenetic and molecular analyses. He had a complex chromosome rea-rrangement of 48,XY,t(8;21)(q22;q22),+13,+13[9]/49,idem,+mar[9]/49,idem,+8[2]. He also had a mutated tyrosine kinase domain in fms-like tyrosine kinase 3 gene. He was treated with antibiotics and glucocorticoids for gastrointestinal infection and urticaria-like skin lesions. The infection and skin lesions were quickly resolved. Unexpectedly, he achieved hematological remission along with resolution of the febrile episode, gastrointestinal symptoms and skin lesions. Notably, after relapse, repeating these treatments resulted in a return to hematological remission. Unfortunately, he demonstrated strong resistance to antibiotic and glucocorticoid treatment after the second relapse and died of sepsis from bacterial infection with multidrug resistance. The main clinical feature of this patient was that symptomatic AML emerged with flaring of the gut inflammatory disorder and it subsided after resolution of the inflammation. Learning from the present case raises the possibility that in a subgroup of AML patients, the proliferative advantage of leukemia cells may critically require the presence of inflammatory stresses.

CONCLUSION

Inflammatory stresses, most likely arising from gastrointestinal infection, may sustain the growth and survival advantage of leukemic cells.

Inhibition of granulocyte colony-stimulating factor–mediated myeloid maturation by low level expression of the differentiation-defective class IV granulocyte colony-stimulating factor receptor isoform

In acute myeloid leukemia (AML), granulocyte colony-stimulating factor receptor (G-CSFR) proliferative and maturational signaling pathways are uncoupled. Seven human G-CSFR mRNA isoforms exist, named class I through class VII. The 183-amino acid cytosolic domain of the class I isoform provides all signaling activities. The class IV isoform is “differentiation defective” because the carboxy-terminal 87 amino acids are replaced with 34 amino acids of novel sequence. In more than 50% of AML samples, the class IV/class I G-CSFR mRNA ratio is aberrantly elevated compared to normal CD34+ bone marrow cells. We hypothesized that the increased relative expression of class IV G-CSFR in AML uncouples proliferative and maturational G-CSFR signaling pathways. To test this, we transfected the G-CSF–responsive murine cell line 32Dcl3 with class IV G-CSFR cDNA. After 10 days of G-CSF stimulation, clones expressing class IV G-CSFR had greater percentages of myeloblasts and promyelocytes than controls (53% ± 13% versus 3% ± 2%). Differential counts over time demonstrated delayed G-CSF–driven maturation in 5 class IV-expressing clones, with 2 clones demonstrating a subpopulation that completely failed to differentiate. Heterologous class IV expression did not affect G-CSF–dependent proliferation. Class IV/murine G-CSFR mRNA ratios after 24 hours of G-CSF stimulation for 3 of the 5 clones (range, 0.090 to 0.245; mean, 0.152 ± 0.055) are within the range of class IV/class I mRNA ratios seen in patients with AML. This indicates that aberrantly increased relative class IV G-CSFR expression seen in AML can uncouple G-CSFR proliferative and maturational signaling pathways.

Inhibition of granulocyte colony-stimulating factor–mediated myeloid maturation by low level expression of the differentiation-defective class IV granulocyte colony-stimulating factor receptor isoform

In acute myeloid leukemia (AML), granulocyte colony-stimulating factor receptor (G-CSFR) proliferative and maturational signaling pathways are uncoupled. Seven human G-CSFR mRNA isoforms exist, named class I through class VII. The 183-amino acid cytosolic domain of the class I isoform provides all signaling activities. The class IV isoform is “differentiation defective” because the carboxy-terminal 87 amino acids are replaced with 34 amino acids of novel sequence. In more than 50% of AML samples, the class IV/class I G-CSFR mRNA ratio is aberrantly elevated compared to normal CD34+ bone marrow cells. We hypothesized that the increased relative expression of class IV G-CSFR in AML uncouples proliferative and maturational G-CSFR signaling pathways. To test this, we transfected the G-CSF–responsive murine cell line 32Dcl3 with class IV G-CSFR cDNA. After 10 days of G-CSF stimulation, clones expressing class IV G-CSFR had greater percentages of myeloblasts and promyelocytes than controls (53% ± 13% versus 3% ± 2%). Differential counts over time demonstrated delayed G-CSF–driven maturation in 5 class IV-expressing clones, with 2 clones demonstrating a subpopulation that completely failed to differentiate. Heterologous class IV expression did not affect G-CSF–dependent proliferation. Class IV/murine G-CSFR mRNA ratios after 24 hours of G-CSF stimulation for 3 of the 5 clones (range, 0.090 to 0.245; mean, 0.152 ± 0.055) are within the range of class IV/class I mRNA ratios seen in patients with AML. This indicates that aberrantly increased relative class IV G-CSFR expression seen in AML can uncouple G-CSFR proliferative and maturational signaling pathways.

Serum interleukin-6 levels in adult acute myelogenous leukemia: relationship with disease characteristics and outcome

Serum interleukin-6 (IL-6) levels were measured in 58 adult patients with newly diagnosed acute myelogenous leukemia (AML) using an ELISA method in order to find potential clinical correlations. Detectable average levels were 57 +/- 68 pg/ml and 52 patients (90%) had higher cytokine levels than normal donors. IL-6 levels (115 +/- 102 pg/ml versus 36 +/- 40 pg/ml, p = 0.0001) were higher in patients with fever of apparently non infectious origin, and higher levels were associated with higher percentage of blasts in the peripheral blood (R = 0.29, p = 0.04) and in the bone marrow (R = 0.39, p = 0.003), elevated serum LDH level (R = 0.36, p = 0.01), hyperbilirubinemia (R = 0.36, p = 0.008), elevated serum GGT level (R = 0.46, p = 0.003), and elevated serum GOT (R = 0.36, p = 0.008) and GPT levels (R = 0.44, p = 0.004). Highest IL-6 levels were observed in FAB M1 (86 +/- 112 pg/ml), M3 (73 +/- 69 pg/ml), and M6 (92 +/- 60 pg/ml) AML subtypes. Serum IL-6 levels in AML might be related to both non specific inflammatory reactions and the specific biology of the disease.

Hematopoietic Growth Factors and Blast Progenitors in Acute Leukemia

Leukemic cells are maintained by a minor subpopulation of cells called leukemic stem cells (LSC) with proliferative and self-renewal capacity, both of which are detected with leukemic colony assay, with the latter being an important prognositic factor. Drug sensitivity tests employing leukemic colony assay revealed the effects of cytotoxic drugs on LSC to be diverse and that cytosine arabinoside predominantly suppresses self-renewal, which probably accounts for its effectiveness in AML therapy. Hematopoietic growth factors (HGFs) regulate the growth of LSC and various in vitro effects of HGFs on acute leukemia cells have been reported. These effects appear to reflect physiological functions of each HGF and can be categorized into groups according to their distinct functions. Endogenously produced HGFs stimulate LSC in an autocrine or a paracrine fashion, resulting in autonomous growth of these cells, which also correlates with the patients' prognosis. HGFs can enhance the cytotoxicity of anti-leukemia drugs in vitro, possibly mainly through recruitment of LSC from the dormant state into active cell cycling. HGFs have been clinically tested in leukemia therapy. Although recovery of blood leukocyte counts can consistently be accelerated with HGF treatment, the effectiveness of HGFs in sensitizing leukemia cells to chemotherapeutic agents and/or improving patient prognosis has not been clearly demonstrated. Different strategies using HGFs and related molecules must be tested in future leukemia therapy.

The expression of IL-6 and its related genes in acute leukemia

Acute myeloid leukemia (AML) blast cells frequently produce interleukin-6 (IL-6) and other cytokines such as colony-stimulating factors (CSF: G-CSF, M-CSF, and GM-CSF), tumor necrosis factor (TNF)-alpha, and IL-1. The AML blast cells that produced IL-6 alone could not form autonomous in vitro colonies, whereas the blast cells that coexpressed CSF in addition to IL-6 were able to form such colonies. This suggests that IL-6 acts as a costimulator to enhance CSF-induced clonogenicity of AML blast cells. TNF-alpha and IL-1 that are produced from the blast cells may stimulate the growth of the AML blast cells by inducing production of CSF in bone marrow stromal cells or in the blast cell population itself. Improvement of clinical manifestations by the administration of an anti-IL-6 murine monoclonal antibody in a patient with AML-M5B confirmed an important role of IL-6 in in-vivo growth of the blast cells. The mRNA expression of IL-6 and its related genes in AML and acute lymphoid leukemia (ALL) blast cells was analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR). IL-6 mRNA expression was common in AML, but rare in ALL, whereas the IL-6 receptor (IL-6R) mRNA was expressed in almost all cases of AML and in more than half of the cases of ALL. In contrast, gp130 was ubiquitously expressed in both AML and ALL. A significant correlation between the levels of IL-6R expression and the responsiveness of the blast cells to exogenous IL-6 was observed. This suggests the possibility of the rapid prediction of the responsiveness of leukemic cells to exogenous IL-6 (IL-6 administration for therapy) by rapid measurement of IL-6R mRNA by RT-PCR.

Interleukins and colony stimulating factors in human myeloid leukemia cell lines

The present review has summarized the expression, production and effects of the human interleukins (IL) 1-11 and myelopoietic colony stimulating factors (CSF) in the established myeloid leukemia cell lines and in cells from patients with acute myeloid leukemia as well as the oncogene expression reported in these myeloid leukemia cell lines. The genetic dissection of leukemic myelopoiesis may provide new perspectives for the control of myeloid leukemias. Based on their expression of phenotypic markers (e.g., surface antigens, cytochemical staining, etc.), myeloid cell lines can be further subdivided into myelogenous, monocytic, erythroid and megakaryoblastic leukemia cell lines. Due to the close relationship of erythroid and megakaryoblastic progenitor cells and to the existence of a probably common precursor cell giving rise to these two different cell lineages, many megakaryoblastic cell lines express erythroid markers (e.g., expression of hemoglobin or glycophorin A) and conversely cell lines with a predominant erythroid profile might display megakaryoblastic features (e.g., platelets peroxidase or glycoproteins CD41, CD42b or CD61). The recent cloning of the specific cytokine: thrombopoietin (TPO) and its receptor generated a strong interest in these particular myeloid cell lines that are discussed in more detail in the present review. Both normal and leukemic megakaryocytopoiesis are stimulated by granulocyte-macrophage colony stimulating factor (GM-CSF), IL-3, GM-CSF/IL-3 fusion protein, IL-6, IL-11 and TPO but inhibited by IL-4, interferon-alpha (IFN-alpha) and IFN-gamma. Human megakaryoblastic leukemia cell lines have common biological features: high expression of the megakaryocytic specific antigen (CD41); high expression of early myeloid antigens (CD34, CD33 and CD13); constitutive expression of IL-6 and platelet-derived growth factor; a complex karyotype picture; expression of c-kit (the stem cell factor receptor); growth-dependency or -stimulation by IL-3 and/or GM-CSF; and in vivo tumorigenicity in mice associated with marked fibrosis. Whereas numerous chemical and biologic agents induce granulocytic and/or monocytic differentiation of myeloid leukemia cell lines, only a few agents including phorbol myristate acetate, vitamin D3, IFN-alpha, IL-6 and thrombin have been reported to induce megakaryocytic differentiation in the megakaryoblastic leukemia cells.

Triggering of the human interleukin-6 gene by interferon-gamma and tumor necrosis factor-alpha in monocytic cells involves cooperation between interferon regulatory factor-1, NF kappa B, and Sp1 transcription factors

We investigated the molecular basis of the synergistic induction by interferon-gamma (IFN-gamma)/tumor necrosis factor-alpha (TNF-alpha) of human interleukin-6 (IL-6) gene in THP-1 monocytic cells, and compared it with the basis of this induction by lipopolysaccharide (LPS). Functional studies with IL-6 promoter demonstrated that three regions are the targets of the IFN-gamma and/or TNF-alpha action, whereas only one of these regions seemed to be implicated in LPS activation. The three regions concerned are: 1) a region between -73 and -36, which is the minimal element inducible by LPS or TNF-alpha; 2) an element located between -181 and -73, which appeared to regulate the response to IFN-gamma and TNF-alpha negatively; and 3) a distal element upstream of -224, which was inducible by IFN-gamma alone. LPS signaling was found to involve NF kappa B activation by the p50/p65 heterodimers. Synergistic induction of the IL-6 gene by IFN-gamma and TNF-alpha, in monocytic cells, involved cooperation between the IRF-1 and NF kappa B p65 homodimers with concomitant removal of the negative effect of the retinoblastoma control element present in the IL-6 promoter. This removal occurred by activation of the constitutive Sp1 factor, whose increased binding activity and phosphorylation were mediated by IFN-gamma.

Retroviral mediated gene transfer in chronic myelogenous leukaemia

Gene therapy for chronic myelogenous leukaemia (CML) may provide a therapeutic option for patients who are ineligible for bone marrow transplantation. To determine the feasibility of such an approach we evaluated the transduction efficiency of CML progenitor colonies from seven patients in chronic phase. Vector transduction was optimized using the CML-derived K562 cell line and applied to CML mononuclear cells. After vector exposure, optimal gene transfer was noted when CML mononuclear cell cultures contained stem cell factor, IL-3, GM-CSF and erythropoietin. The addition of IL-6 to this combination decreased transduction efficiency. Using these conditions, 20.4% +/- 2.4 (SE) of erythroid colonies (CFU-GEMM and BFU-E) and 20.2% +/- 4.7 of CFU-GM colonies were G418 resistant. This compares with a transduction efficiency of 5.9% +/- 1.1 and 6.4% +/- 1.5, respectively, for erythroid and CFU-GM colonies using marrow obtained from normal donors. Only a modest increase in gene transfer was noted when CML cells were stimulated with cytokines for the 24 h preceding vector exposure. Vector DNA in colonies expressing the BCR/ABL transcript was documented by performing PCR analysis on individual colonies. The relatively high gene transfer rate in CML suggests that this disease might be very suitable for gene therapy.

Long-term survivors in chronic granulocytic leukaemia: a study by the International CGL Prognosis Study Group. Italian Cooperative CML Study Group

The purpose of the present work were to identify the initial characteristics associated with long-term survival in chronic granulocytic leukaemia (CGL) and to analyse the accuracy of prognostic models in identifying long-term survivors. 813 Philadelphia (Ph) chromosome-positive, nonblastic CGL patients from six American and European institutions, the majority treated conventionally, with a minimum follow-up > 10 years, were studied. Stepwise logistic regression was performed to ascertain the association between the initial clinicohaematological variables and survival > or = 8 years, and a prognostic index was derived. The usefulness of both Sokal's and the new prognostic index to identify long-term survivors was assessed by calculating their positive and negative predictive accuracies, sensitivity and specificity. Median survival of the series was 45 months (range 1-255), with 784 patients (96.4%) having died and 109 (13.4%) surviving 8 years or longer. Younger age, smaller spleen, platelets < or = 600 x 10(9)/l, and lower blood blast percentage were associated with survival > or = 8 years; platelets < or = 600 x 10(9)/l and lower blood blast percentage were the predictive factors in patients 50 years old or younger. Two-thirds of long survivors belonged to Sokal's low-risk group, but the positive predictive accuracy and specificity for prolonged survival of Sokal's index were very low. This was also the case for the new predictive index.(ABSTRACT TRUNCATED AT 250 WORDS)

Southwestern Internal Medicine Conference: clinical use of hematopoietic growth factors

The hematopoietic growth factors, granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF), have been cloned, produced in bacteria and yeast, and approved for clinical use in the treatment of neutropenia. Both factors stimulate the proliferation and maturation of neutrophil progenitors and enhance the effector functions of mature cells by interaction with specific receptors on the cell surface. Serum levels of G-CSF correlate inversely with the neutrophil count, suggesting that G-CSF may be the normal homeostatic regulator of the neutrophil count, while GM-CSF is generally undetectable in the serum and appears under normal physiologic conditions to act locally at inflammatory sites. Phase I and II clinical trials with these factors demonstrated minimal toxicity for G-CSF and mild to moderate dose-dependent toxicity for GM-CSF. Recent clinical trials, including double-blind, randomized studies, support a role for these growth factors in the treatment of chronic neutropenias, such as Kostmann's syndrome, acquired immune deficiency syndrome (AIDS), aplastic anemia, and myelodysplasia, as well as in acute neutropenias, such as cyclic neutropenia, chemotherapy-induced neutropenia, and bone marrow transplantation.

Increased serum interleukin 6 levels in patients with myelodysplastic syndromes

Serum concentration of interleukin 6 (IL-6) was measured in 45 patients with myelodysplastic syndromes (MDS). A commercially available enzyme-linked immunosorbent assay (ELISA) with a sensitivity of 3 pg/ml was used. While IL-6 was undetectable in healthy volunteers, 32 of the patients with MDS showed IL-6 concentrations higher than 3 pg/ml. In MDS we found serum concentrations of IL-6 between 0 and 150 pg/ml with a median of 9 pg/ml, mean and standard deviation (SD) were 15 and 26 pg/ml respectively. In refractory anemia with excess of blasts in transformation (RAEB-t) the serum IL-6 concentrations were significantly higher than in refractory anemia (RA; p = 0.0025), in refractory anemia with excess of blasts (RAEB; p = 0.0050) and in chronic myelomonocytic leukemia (CMML; 0.0449). No significant difference was detected between RA and RAEB or between CMML and the other types of MDS, while s significant negative correlation was found between the concentrations of IL-6 and hemoglobin (p = 0.0228).

Effects of granulocyte-macrophage colony-stimulating factor and interleukin 6 on the growth of leukemic blasts in suspension culture

We examined the stimulatory effects of recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin 6 (IL)-6 on the in vitro proliferation of leukemic blast cells from patients with acute leukemia. Bone marrow or peripheral blood leukemic blast cells were obtained from 21 patients, including 14 cases of acute myeloblastic leukemia (AML), four cases of acute lymphoblastic leukemia (ALL), two cases of acute undifferentiated leukemia, and one case of acute mixed-lineage leukemia. The proliferation of leukemic blast cells was evaluated by measuring the incorporation of 3H-thymidine into cells incubated with various concentrations of cytokines for 3 days. GM-CSF stimulated the DNA synthesis (with greater than 2.0 stimulation index) of blast cells in 9 of 14 (64%) AML cases, two cases of acute undifferentiated leukemia and one case of acute mixed-lineage leukemia. Only two cases of AML blasts responded to IL-6 to grow in the short-term suspension cultures. GM-CSF and IL-6 did not display a synergistic effect on the growth of leukemic cells. Moreover, GM-CSF and IL-6 did not stimulate the proliferation of ALL blast cells. Binding study also revealed the specific binding of GM-CSF on the blast cells of acute undifferentiated leukemia and acute mixed-lineage leukemia. Our results indicated that leukemic blast cells of acute undifferentiated leukemia and acute mixed-lineage leukemia possessed functional GM-CSF receptors.

Enhancement by transforming growth factor-beta 1 (TGF-beta 1) of the proliferation of leukemic blast progenitors stimulated with IL-3

We studied the effect of transforming growth factor-beta 1 (TGF-beta 1) on colony formation of leukemic blast progenitors from ten acute myeloblastic leukemia (AML) patients stimulated with granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), interleukin-6 (IL-6), or interleukin-1 beta (IL-1 beta). These CSFs and interleukins by themselves stimulated the proliferation of leukemic blast progenitors without adding TGF-beta 1. G-CSF, GM-CSF, and IL-3 stimulated blast colony formation in nine patients, IL-6 stimulated it in five, and IL-1 beta stimulated in four. TGF-beta 1 significantly reduced blast colony formation stimulated by G-CSF, GM-CSF, or IL-6 in all patients. In contrast, TGF-beta 1 enhanced the stimulatory effect of IL-3 on blast progenitors from three cases, while in the other seven patients TGF-beta 1 reduced blast colony formation in the presence of IL-3. To study the mechanism by which TGF-beta 1 enhanced the stimulatory effect of IL-3 on blast progenitors, we carried out the following experiments in the three patients in which it occurred. First, the media conditioned by leukemic cells in the presence of TGF-beta 1 stimulated the growth of leukemic blast progenitors, but such effect was completely abolished by anti-IL-1 beta antibody. Second, the addition of IL-1 beta in the culture significantly enhanced the growth of blast progenitors stimulated with IL-3. Third, leukemic cells of the two patients studied were revealed to secrete IL-1 beta and tumor necrosis factor-alpha (TNF-alpha) constitutively; the production by leukemic cells of IL-1 beta and TNF-alpha was significantly promoted by TGF-beta 1. Furthermore, the growth enhancing effect of TGF-beta 1 in the presence of IL-3 was fully neutralized by anti-IL-1 beta antibody. These findings suggest that TGF-beta 1 stimulated the growth of blast progenitors through the production and secretion of IL-1 beta by leukemic cells.

Recombinant granulocyte colony-stimulating factor (rG-CSF). A review of its pharmacological properties and prospective role in neutropenic conditions

Recombinant granulocyte colony-stimulating factor (rG-CSF) is a glycoprotein hormone which has been produced in mammalian cells and, in a nonglycosylated form, in the bacterium Escherichia coli through recombinant DNA technology. It stimulates proliferation, differentiation and activation of cells of the neutrophil-granulocyte lineage and has been investigated as therapy for patients with various neutropenic conditions, both iatrogenic and disease related. rG-CSF is well tolerated, the most frequently reported adverse effect being mild to moderate bone pain. A major use for rG-CSF therapy will be in ameliorating the neutropenia which follows cytoreductive chemotherapy. rG-CSF accelerates neutrophil recovery after chemotherapy, leading to a reduction in duration of the neutropenic phase. Consequently, infection rate is diminished, as is the associated usage of antibiotics and duration of hospitalisation. The implications are that rG-CSF may allow increased dose intensity and stricter adherence to chemotherapy schedules. The increase in neutrophils produced by rG-CSF renders it a useful treatment for conditions such as congenital, acquired and cyclic neutropenias for which current therapy is not very successful. rG-CSF may be an effective therapy in myelodysplasia, although there is concern about acceleration of the possible rate of conversion of this disease to acute myelogenous leukaemia. It is also likely that rG-CSF will be useful in accelerating the recovery of transplanted bone marrow in patients with leukaemia, lymphoma and solid tumour. Furthermore, there is great potential for expansion of the role of rG-CSF as monotherapy or in combination regimens with other cell factors in various haematological disorders such as aplastic anaemia. In summary, while many aspects of its use remain to be clarified, rG-CSF must be seen as an exciting advance in therapeutics. It should rapidly find an important place as an adjunct to cancer chemotherapy, and also appears to have substantial potential in a number of other neutropenic conditions which are currently difficult to treat.

Interleukin 4 suppresses the spontaneous growth of chronic myelomonocytic leukemia cells

We studied the effects of IL-4 on the spontaneous proliferation of chronic myelomonocytic leukemia (CMMoL) cells in vitro. IL-4 (100 U/ml) suppressed the spontaneous DNA synthesis by approximately 50% in 5 of 8 cases examined. IL-4 (100 U/ml) also inhibited the spontaneous colony formation by CMMoL cells in a methylcellulose culture by 50-97% in all of the 10 cases in which spontaneous colonies were formed. This IL-4-mediated suppression of the growth of CMMoL cells was completely abolished by the addition of anti-IL-4 neutralizing antibodies. The spontaneous CMMoL colonies were substantially suppressed by the addition of either anti-IL-6 or anti-granulocyte/macrophage colony-stimulating factor (GM-CSF) antibodies to the colony assay system: the addition of both anti-IL-6 and anti-GM-CSF antibodies resulted in greater than 80% inhibition of the colony formation by CMMoL cells. On the other hand, none of anti-IL-1-beta, anti-granulocyte-CSF, anti-macrophage-CSF, or anti-tumor necrosis factor-alpha antibodies affected the CMMoL colony formation. In the supernatants from 24-h cultures of CMMoL cells, high levels of IL-6 and GM-CSF were demonstrated in 9 of 9 and 2 of 9 cases examined, respectively. IL-4 (100 U/ml) almost completely inhibited the secretion of IL-6 and GM-CSF by CMMoL cells. These observations suggest that IL-4 suppresses the spontaneous proliferation of CMMoL cells by inhibiting their production of IL-6 and/or GM-CSF, both of which could act in vitro as an autocrine growth factor for CMMoL cells.