Allele and haplotype frequency at human leucocyte antigen class I/II and immunomodulatory cytokine loci in patients with myelodysplasia and acute myeloid leukaemia: in search of an autoimmune aetiology

An autoimmune mechanism in the pathogenesis of myelodysplastic syndrome (MDS) is suggested by response to immunosuppression, with CD8+ T-lymphocytes implicated in the haematopoietic suppression. We therefore sought evidence for human leucocyte antigen (HLA) restriction and variant frequency differences in selected polymorphisms at the loci for the immunomodulatory cytokines, tumour necrosis factor alpha (TNF-alpha), lymphotoxin-alpha (LT-alpha) and interleukin 10 (IL-10) in patients with MDS and acute myeloid leukaemia (AML) compared with normal controls. DNA from 150 MDS/AML patients [24 AML, 53 refractory anaemia (RA), 25 RA with excess blasts (RAEB), four RAEB in transformation (RAEBt), 21 sideroblastic leukaemia, 22 chronic myelomonocytic leukaemia] was screened. Control data was from Scottish blood donors (HLA class I/II), healthy General Practitioner-based subjects (TNF-alpha/LT-alpha) and published values (IL-10). HLA class I/II haplotypes were determined using sequence-specific primers. Polymorphisms were assayed at TNF-alpha -308, LT-alpha +252 and IL10 -824, -597 and -1082 loci. Variant frequencies of common haplotypes at HLA class I and II, high-/low-producer TNF-alpha/LT-alpha and IL-10 loci were not different between patients and controls or within the French-American-British, International Prognostic Scoring System or cytogenetic subgroups and were not associated with altered survival for MDS/AML patients. TNF2 allele frequency was greater in the MDS/AML cohort (chi2 = 6.593, P < 0.05) but the biological significance was uncertain in the absence of an increased high-producer TNF-alpha/LT-alpha haplotype frequency. We can find no genetic influence for these polymorphisms in HLA class I/II, TNF-alpha/LT-alpha and IL-10 loci on either predisposition or disease progression in MDS/AML.     

Effects of recombinant human stem cell factor (rh-SCF) on colony formation and long-term bone marrow cultures (LTBMC) in patients with myelodysplastic syndromes

Abstract: Stem cell factor (SCF), the ligand of the c-kit receptor, is a potent enhancing cytokine for haematopoietic cells in the presence of IL-3, GM-CSF and erythropoietin (Epo). In the clonogenic assays of 63 MDS patients, the addition of rh-SCF + GM-CSF and/or IL-3 induced a significant increase (p<0.001) in the number and size of CFU-GM. Never reaching the levels of controls, this increase was seen in all FAB subtypes, but particularly in RA. There was no significant increase in cluster formation, even in RAEB or RAEBt. Rh-SCF (10 ng/ml) led to mean increases of up to 26 times in the number of Epo-dependent BFU-E colonies, particularly in RA (p<0.001) and RAEB (p<0.05). Individual responses varied widely (especially in RA) from no response to supranormal levels. Added to the weekly refeed of 37 MDS LTBMC, SCF (10 ng/ml) induced only a 7% mean increase in both cell output and the number of clonogenic cells recovered in the supernatant. Immunohistochemical examination of the supernatant showed significant increases in differentiating myeloid cells in all examined cases, and in erythroid cells in 3 cases; blast cells increased in only 3 cases. These data suggest that rh-SCF is capable of at least partially reversing defective MDS myeloid haematopoiesis, and leads no overt risk of leukaemic transformation. Its potent effect on erythroid cells is encouraging for future clinical applications in patients, particulary if they are selected by means of in vitro tests.     

血清bFGF水平与MDS分型及预后的关系研究

目的研究骨髓增生异常综合征(MDS)患者血清碱性成纤维细胞生长因子(bFGF)水平与MDS分型、发展及预后的关系。方法应用双抗体夹心酶联免疫吸附法检测MDS、急性髓细胞白血病(AML)患者和正常人的bFGF水平,分析其与MDS分型及临床因素的关系。结果MDS患者血清bFGF水平明显高于正常,其中RAEB、RAEBT型均明显高于RA、RAS型,RAEB、RAEBT组与急性髓细胞白血病(AML)组无显著差异,bFGF水平与患者的外周血常规、骨髓原始细胞比例有关。结论血清bFGF水平与MDS的分型、发展及预后有关。     

急性髓系白血病及骨髓增生异常综合征患者血管内皮生长因子表达的研究

目的了解血管内皮生长因子(VEGF)在急性髓系白血病(AML)和骨髓增生异常综合征(MDS)中血管新生的作用。方法用ELISA法检测20例AML及24例MDS患者骨髓单个核细胞培养上清VEGF的表达。结果AML患者骨髓细胞VEGF的水平(267.35～412.30ng/L)高于对照组(128.17ng/L),化疗后完全缓解组的VEGF水平明显下降(P<0.05)化疗后未缓解组的VEGF水平与治疗前比较无显著下降(P>0.05)。MDS高危型(RAEB或RAEBt)中VEGF水平与低危型(RA或RAS)及对照组相比均明显升高(P<0.05),其中RAEBt与AML患者相比差异无显著性(P>0.05)。结论AML及高危型MDS患者骨髓中存在血管新生,VEGF在AML及MDS发病中起着重要作用,VEGF的表达与MDS病程进展有关。     

Levels of soluble forms of ICAM and VCAM in patients with myelodysplastic syndromes and their prognostic significance

The aim of this study was to assess circulating soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1), and interleukin-1beta (IL-1beta) in myelodysplastic syndromes (MDS) in order to evaluate their clinical significance. Seventy patients with untreated MDS [21 refractory anemia (RA), nine RA with ringed sideroblasts (RARS), 17 RA with excess of blasts (RAEB), 11 RAEB in transformation (RAEBt), and 12 chronic myelomonocytic leukemia (CMML)] were included in this study. Serum levels of sICAM, sVCAM, and IL-1beta were determined at diagnosis using commercially available immunoassays. In addition, 15 healthy volunteers were studied as a control group. sICAM, sVCAM, and IL-1beta serum levels were significantly higher in MDS patients in comparison with the control group (P <0.001). Patients with CMML showed the highest sICAM, sVCAM, and IL-1beta levels in comparison with other MDS-related subtypes. Furthermore significantly elevated levels of the studied parameters were detected in high-risk MDS patients (RAEB, RAEB-t, and CMML) in comparison with low-risk MDS (RA and RARS). IL-1beta was strongly correlated both to sICAM and sVCAM. In conclusion we have provided evidence that increased sICAM and sVCAM serum levels are related to MDS severity.     

The effect of stem-cell factor,interleukin-3 and erythropoietin on in vitro erythropoiesis in myelodysplastic syndromes

An inherent defect of erythroid differentiation at the colony-forming unit blast (CFU-blast) compartment and (or) an impaired response of early erythroid progenitors (BFU-E) to growth stimulation are both considered to contribute to anemia in myelodysplastic syndromes (MDS). With the intention of improving survival and growth of early erythroid progenitors we investigated the effect of stem-cell factor (SCF) and interleukin-3 (IL-3) alone and in combination with erythropoietin, on the in vitro erythropoiesis of 13 patients with MDS and of three normal controls. SCF and IL-3 alone did not promote erythroid colony growth in MDS, while 3 cases responded to erythropoietin alone. In each of these, BFU-E colony growth could be increased by SCF, which was also found in all normal bone marrows. Altogether 6 cases showed a significant enhancement of BFU-E colony numbers by the combination of SCF and erythropoietin as compared to erythropoietin alone (P=0.036). Out of the 6 responding cases, 5 belonged to the FAB-classified subgroups refractory anemia (RA) and refractory anemia with ringed sideroblasts (RA/RS) (5/5), while 1 patient was classified as having refractory anemia with excess of blasts (RAEB) (1/4). No patient with refractory anemia with excess of blasts in transformation (RAEB-T) (0/4) responded. In spite of these positive effects, the absolute number of BFU-E colonies remained reduced in all MDS cases when compared to normal controls. IL-3 proved ineffective in increasing the response to erythropoietin in MDS although it increased erythropoietin-induced BFU-E formation in normal controls significantly. We conclude that the striking synergistic effect of SCF and erythropoietin on erythroid colony formation seen with normal bone marrow is conserved in most cases with RA and RA/RS. In RAEB and RAEB-T the intrinsic defect of the erythroid differentiation pathway cannot be overcome by SCF.Abbreviation MDS myelodysplastic syndrome - SCF stem-cell factor - II-3 interleukin-3 - RA refractory anemia - RA/RS RA with ringed sideroblasts - RAEB RA with excess of blasts - RAEB-T RA with excess of blasts in transformation - Epo erythropoietin     

CD34/QBEND10 immunostaining in bone marrow biopsies: an additional parameter for the diagnosis and classification of myelodysplastic syndromes

CD34/QBEND10 immunostaining has been assessed in 150 bone marrow biopsies (BMB) including 91 myelodysplastic syndromes (MDS), 16 MDS-related AML, 25 reactive BMB, and 18 cases where RA could neither be established nor ruled out. All cases were reviewed and classified according to the clinical and morphological FAB criteria. The percentage of CD34-positive (CD34 +) hematopoietic cells and the number of clusters of CD34+ cells in 10 HPF were determined. In most cases the CD34+ cell count was similar to the blast percentage determined morphologically. In RA, however, not only typical blasts but also less immature hemopoietic cells lying morphologically between blasts and promyelocytes were stained with CD34. The CD34+ cell count and cluster values were significantly higher in RA than in BMB with reactive changes (p<0.0001 for both), in RAEB than in RA (p=0.0006 and p=0.0189, respectively), in RAEBt than in RAEB (p=0.0001 and p=0.0038), and in MDS-AML than in RAEBt (p<0.0001 and p=0.0007). Presence of CD34+ cell clusters in RA correlated with increased risk of progression of the disease. We conclude that CD34 immunostaining in BMB is a useful tool for distinguishing RA from other anemias, assessing blast percentage in MDS cases, classifying them according to FAB, and following their evolution.     

Prognostic factors in the myelodysplastic syndromes: importance of initial data on peripheral blood counts, bone marrow cytology, trephine biopsy and chromosomal analysis

An analysis of clinical, haematological, histological and cytogenetic data was performed in 85 consecutive patients with myelodysplastic syndromes (MDS). The criteria for diagnosis of refractory anaemia (RA), acquired idiopathic sideroblastic anaemia (AISA) and chronic myelomonocytic leukaemia (CMML) were clearly defined, since the inclusion criteria provided by the FAB co-operative group are imprecise. None of these patients has received chemotherapy during the follow-up period. The median survival of the whole group was only 15 months, with less than 10% of the patients surviving after 5 years. Fifteen patients (17.6%) were still alive at time of analysis, 31 (36.5%) have developed acute myeloid leukaemia (AML) and only one of them is still alive; 30 (35.3%) died of infectious and/or haemorrhagic complications. Patients who developed AML had a shorter survival (median survival time 9.5 versus 15 months) but this difference was not significant (P = 0.10). Factors with prognostic value are in order of significance: abnormal localized immature myeloid precursors (= ALIP) in the trephine biopsy, circulating myeloblasts, excess of blasts in the bone marrow smears, age, FAB classification and granulocyte count. In comparison to refractory anaemia with excess of blasts (RAEB), CMML and RAEB in transformation (RAEBt), patients with RA and AISA had a lower incidence of evolution to AML (11% versus 56%), but a higher mortality rate from infections and/or bleeding (59.2% versus 29%). ALIP negative cases were only found among patients with RA and AISA, whereas ALIP positivity was observed in all cases of RAEB and RAEBt, in 10/11 patients with CMML and in almost half the cases of RA and AISA. In RA and AISA patients survival was significantly different between ALIP positive and ALIP negative cases (P = 0.009). Among MDS patients, ALIP negative cases developed significantly less AML than ALIP positive cases (5% versus 44%), but a similar percentage of mortality from infectious and/or haemorrhagic complications was seen in both groups (33% versus 36.5%). Chromosomal analysis proved to be of no significant prognostic value, although a trend for shorter survival was observed in patients with complex karyotype anomalies or without mitoses. Because of their prolonged survival, antileukaemic chemotherapy is contra-indicated in ALIP negative patients (median survival 50 months). Nevertheless they only constitute a minor subgroup of MDS cases. Prognosis in ALIP positive patients is poor (median survival 12.5 months); in these patients therapeutic trials with cytostatic drugs or with inducers of differentiation of myeloid precursor cells seem to be justified.     

A combination of megakaryocyte growth and development factor and interleukin-1 is sufficient to culture large numbers of megakaryocytic progenitors and megakaryocytes for transfusion purposes

Chemotherapy-induced thrombocytopenia is a major risk factor in cancer treatment. The transfusion of autologous ex vivo expanded megakaryocytes could be a new therapy to shorten the period of thrombocytopenia. Therefore we investigated, in a liquid culture system, the effect of various cytokine combinations composed of pegylated megakaryocyte growth and development factor (PEG-rHuMGDF), interleukin-1 (IL-1), IL-3, IL-6, IL-11 and stem cell factor (SCF) on the proliferation and differentiation of CD34+ cells, in order to define the most optimal and minimum levels of cytokine combinations for megakaryocyte expansion. Besides PEG-rHuMGDF, IL-1 was found to be important for optimal megakaryocyte expansion. Depletion of either SCF, IL-6 or IL-11 did not exert a large effect, but the absence of IL-1 strongly diminished the number of megakaryocytic cells. Addition of IL-3 to the combination PEG-rHuMGDF, IL-1, IL-6, IL-11 and SCF significantly reduced the number of megakaryocyte progenitors (CD34+CD41+ cells) and the number of CFU-Meg. Furthermore, we found a strong correlation between the number of CD34+CD41+ cells and the number of CFU-Meg obtained after 8 d culture. Our study shows that optimal ex vivo expansion of megakaryocytes is achieved by the combination of PEG-rHuMGDF and IL-1. The numbers of megakaryocytes and megakaryocyte progenitors (CD34+CD41+) obtained in our liquid culture system with the growth factor combination PEG-rHuMGDF and IL-1 are suitable for transfusion purposes.     

High incidence of somatic mutations in the AML1/RUNX1 gene in myelodysplastic syndrome and low blast percentage myeloid leukemia with myelodysplasia

A high incidence of somatically acquired point mutations in the AML1/RUNX1 gene has been reported in poorly differentiated acute myeloid leukemia (AML, M0) and in radiation-associated and therapy-related myelodysplastic syndrome (MDS) or AML. The vast majority of AML1 mutations identified in these diseases were localized in the amino (N)-terminal region, especially in the DNA-binding Runt homology domain. In this report, we show that AML1 point mutations were found in 26 (23.6%) of 110 patients with refractory anemia with excess blasts (RAEB), RAEB in transformation (RAEBt), and AML following MDS (defined these 3 disease categories as MDS/AML). Among them, 9 (8.2%) mutations occurred in the carboxy (C)-terminal region, which were exclusively found in MDS/AML and were strongly correlated with sporadic MDS/AML. All patients with MDS/AML with an AML1 mutation expressed wild-type AML1 protein and had a significantly worse prognosis than those without AML1 mutations. Most AML1 mutants lost trans-activation potential, regardless of their DNA binding potential. These data suggested that AML1 point mutation is one of the major driving forces of MDS/AML, and these mutations may represent a distinct clinicopathologic-genetic entity.     

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.     

Detection of soluble IL-2 receptor in the serum of patients with myelodysplastic syndromes: induction under therapy with GM-CSF

Sera of 15 healthy controls and 33 patients suffering from myelodysplastic syndromes (MDS) were investigated for soluble interleukin-2 receptor (sIL-2R) expression with a cell-free enzyme-linked immunosorbent assay (ELISA) system (T-Cell Sciences; Cambridge, U.S.A.). The upper limit of the assay is indicated with 477 U/ml. According to the FAB classification eight refractory anaemia (RA), 15 refractory anaemia with excess of blasts (RAEB), five refractory anaemia with excess blasts in transformation (RAEBt) and five chronic myelomonocytic leukaemia (CMML) were examined. None of the patients had reported infectious episodes or been under treatment with cytotoxic agents and/or cytokines within the previous 3 months. Significant differences in sIL-2R levels between RA (median 368 U/ml). RAEB (median 675 U/ml) and RAEBt (median 971 U/ml) and between RA and CMML (median 723 U/ml) were detected. Six patients, who had been under treatment with rhGM-CSF for at least 2 weeks, demonstrated a three- to sevenfold increase of sIL-2R expression compared to pretreatment levels. In kinetic evaluation of serum samples for 24 h, the increase of sIL-2R expression begins within 4 h after subcutaneous application of GM-CSF and reaches its maximum after 12 h. Our data cannot suggest whether increased sIL-2R expression is a primary event due to involvement of lymphocytes in the malignant clone or whether it results from secondary alteration of the cytokine network. Application of GM-CSF in MDS may result in improvement of altered lymphocyte function. As GM-CSF induces sIL-2R expression, a down regulation of the immune response caused by neutralization of free IL-2 cannot be excluded.     

The in vitro effect of pegylated recombinant human megakaryocyte growth and development factor (PEG rHuMGDF) on megakaryopoiesis in normal subjects and patients with myelodysplasia and acute myeloid leukaemia

Mpl ligand is a recently cloned haemopoietic growth factor that stimulates megakaryopoiesis in vitro and in vivo . We describe the in vitro effect of a truncated form of Mpl ligand, recombinant human megakaryocyte growth and development factor (rHuMGDF), on megakaryopoiesis in bone marrow from normal subjects and patients with myelodysplastic syndrome (MDS) and acute myeloid leukaemia (AML). We used both semi-solid and suspension culture techniques to assess the effect of pegylated (PEG) rHuMGDF on megakaryocyte colony growth (CFU-Mk) and on the production of CD61⁺ cells in 7 d suspension cultures. PEG rHuMGDF increased CFU-Mk growth and CD61⁺ cell production in a dose-dependent fashion in all normal marrows tested. Normal CFU-Mk growth was increased threefold with the addition of 10 ng/ml PEG rHuMGDF to cultures and CD61⁺ cells were increased 8–10-fold by the same dose. Although increased CFU-Mk growth was only seen in 1/10 AML and 6/16 MDS marrows, CD61⁺ cell numbers in suspension culture were increased in 9/13 AML and 12/15 MDS samples, responses ranged from very limited to normal magnitude. There was no correlation between platelet count and CFU-Mk number, CD61⁺ cell number or response to PEG rHuMGDF. We did not find any increased CFU-GM colony or cluster growth in response to PEG rHuMGDF and the CD61⁺ cells produced in suspension culture had features of megakaryocytic differentiation. These data suggest that PEG rHuMGDF can enhance megakaryocyte proliferation in some patients with MDS and AML, and may have a role in the treatment of thrombocytopenia in these patients.     

Therapeutic effect of heme arginate in myelodysplastic syndromes.

In order to investigate, whether heme would induce a response in myelodysplastic syndromes (MDS), 14 symptomatic patients (4 RA, 3 RARS and 7 RAEB) were treated with infusions of heme arginate 3 mg/kg body weight on 4 consecutive days, mostly for six cycles at 2-week intervals. Three of 14 patients (21%) showed an improvement in anemia (97-152, 79-120 and 92-114 g/l) within a few weeks, and 1 showed a milder increase in hemoglobin level (102-118 g/l). Of the 2 responders with marked thrombocytopenia, 1 showed an improvement in the platelet count (7-37 x 10(9)/l) and her regular need for red cell and platelet transfusions ceased. Some regression in bone marrow (BM) cytology was seen in all 3 responders. One of the responders is still in remission 41 months after cessation of the treatment, while in the other 2 the response lasted for 26 and 5 months. Four patients progressed during the treatment: 1 RA to RAEB, 1 RAEB to RAEBt and 2 RAEB, both with very complex chromosomal abnormalities at the beginning of the therapy, to acute erythroleukemia (AML-M6). Pretreatment delta-aminolevulinic acid synthase and heme synthase activities were generally low. Five patients had mild thrombophlebitis, but not after the infusion procedure was changed. No other side-effects common to growth factors occurred. In conclusion, it is likely that heme arginate has a therapeutic effect on some MDS patients, obviously by stimulating erythropoiesis. The response may be long-lasting.     

Effect of cytokines on growth and differentiation of leukaemic cells with translocation t(6;9)(p23;q34)

The translocation t(6;9)(p23;q34) is detected infrequently in subtypes of haematological malignancies including acute myelogenous leukaemia (AML) and myelodysplastic syndrome (MDS). Although the t(6;9) leukaemia is commonly associated with bone marrow basophilia, the cytological characteristics of leukaemic cells are unclear. In the current study, we examined the in vitro effects of several cytokines on growth and differentiation of t(6;9) leukaemic cells. Isolated bone marrow mononuclear cells from four patients with t(6;9) (two MDS and two AML) were cultured for 14 d in the presence or absence of each cytokine. At the end of culture, viable cells were counted, and their histology was examined. Bone marrow cells obtained from 22 patients (10 AML, six AML from MDS, six MDS) lacking t(6;9) were used as controls. Compared with control cultures, significantly higher numbers of blasts appeared in the culture of bone marrow cells from t(6;9)-positive patients in response to stimulation with granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage CSF (GM-CSF) or interleukin 3 (IL-3). Stem cell factor (SCF) had little effect. Neutrophil counts were also significantly increased in the presence of G-CSF or IL-3. SCF and IL-3 were potent in increasing basophil counts from t(6;9)-positive cultures. These findings suggest that bone marrow cells obtained from t(6;9) patients are highly sensitive to growth- and/or differentiation-promoting cytokines. Special attention should be paid to the use of "therapeutic" cytokines in these patients.     

Deficiency of pluripotent hemopoietic progenitor cells in myelodysplastic syndromes

Summary Pluripotent (CFU-MIX), erythroid (BFU-E) and granulocyte/macrophage (CFU-GM) progenitor cells were examined in bone marrow (BM) from 23 patients with myelodysplastic syndromes (MDS). Patients were grouped according to the FAB classification: Refractory anemia (RA), n=3; RA with ring sideroblasts (RARS), n=3; RA with excess of blasts (RAEB), n=8; RA with excess of blasts in transformation (RAEBt), n=7; chronic myelomonocytic leukemia (CMML), n=2. In FAB groups RA, RARS, RAEB and RAEBt CFU-GM concentrations were normal or decreased but both CMML-patients had increased CFU-GM values. Abnormal cluster growth was observed in 9 of 23 MDS-patients. BFU-E colony formation was subnormal in all cases. Mixed-colony assay values were at the lower limit of controls in one patient and decreased in the remaining 22 MDS-patients. A similar growth pattern of hemopoietic progenitor cells was observed in 19 patients with acute nonlymphocytic leukemia (ANLL), who were studied for comparison. These data suggest a quantitative or qualitative/functional defect of the pluripotent progenitor cell compartment as the major cause for the cytopenia in MDS-patients.     

Neutrophil-specific reduction in the expression of granulocyte--macrophage colony-stimulating factor receptor subunits in myelodysplastic syndromes

The proliferative and differentiative response of neutrophils to granulocyte-macrophage colony-stimulating factor (GM-CSF) is known to be impaired in patients with myelodysplastic syndromes (MDS). To investigate the mechanisms of the defective response in MDS, we examined expression levels of GM-CSF receptor alpha (GMR alpha) and common beta (beta c) subunits on CD16(+) neutrophils, CD14(+) monocytes and CD3(+) T cells from 26 MDS patients and 10 healthy controls using flow cytometry. Expression of GMR alpha was significantly decreased on the neutrophils of five out of 26 patients and was not specific for any FAB subtype. In contrast, beta c expression on neutrophils was significantly reduced in 14 out of 26 patients with a higher proportion occurring in the advanced stages of MDS including refractory anaemia with excess of blasts (RAEB), RAEB in transformation (RAEBt) and overt leukaemia compared with refractory anaemia (RA)/RA with ringed sideroblasts (RARS) or healthy controls. Decreased beta c also correlated with the degree of hypogranular neutrophil morphology and increased infection. Expression of both subunits on T cells and monocytes in MDS was similar to normal controls. Polymerase chain reaction amplification of reverse-transcribed mRNA isolated from the affected neutrophils suggests that the reduction of beta c may result from decreased message levels. The observed reduction in GM-CSF receptor expression could account for the impaired proliferative and maturational responses in MDS.     

Megakaryocytic growth in patients with refractory anemia is suppressed by treatment with interferon alpha.

IFN alpha alone or in combination with retinoids or haematopoietic growth factors has been used to treat patients with early MDS because of its properties as a differentiation inducing agent. We investigated whether treatment of patients with refractory anemia (RA) with IFN alpha (1.5x10(6) IU twice a week) and intermittent all-trans retinoic acid (ATRA, 25 mg/m2/d) influences in-vitro megakaryocytic (MK) proliferation and differentiation stimulated by PEG-rHuMGDF. Low-density non-adherent bone marrow (BM) cells from 8 patients with RA were assayed prior to any treatment other than supportive and after a period of 6 months of treatment. MK development was assayed in suspension cultures in the presence of PEG-rHuMGDF and SCF for 7 d using morphological criteria and flow cytometric analysis of CD42b (GP1b) positive cells. BM-cells from 10 healthy individuals served as control. Following stimulation with PEG-rHuMGDF 23+/-7% and 16+/-4% of control cells were CD42b positive after 5 and 7 d of cultures, respectively. In cultures of cells from MDS patients prior to treatment 8+/-2% and 7+/-3% of cells were CD42b+ on days 5 and 7. In the course of IFN alpha treatment cultures of all BM samples from these MDS patients revealed a significant reduction of MK precursor cells (3+/-2%, CD42b+, p=0.03 and 0.04). In conclusion, treatment with TFN alpha and ATRA did not result in improved megakaryocytopoiesis as assessed by in-vitro cultures. On the contrary, low-dose IFN alpha appears to suppress cell proliferation as well as MK development.