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A novel long-term cultured interleukin (IL)-3-dependent human myelodysplastic cell line, MDS92, was shown to contain several myeloid-lineage cells such as neutrophils, macrophages, eosinophils, and a small number of megakaryocyte-lineage cells. Therefore this cell line possesses at least bipotential characteristics of myeloid- and megakaryocyte-lineages. Granulocyte colony-stimulating factor clearly promoted the neutrophil alkaline phosphatase activity of MDS92 cells. To the contrary, the incidence and growth of CD41-positive cells were hardly affected by the addition of IL-6, IL-11, c-mpl ligand (thrombopoietin, TPO) or erythropoietin. TPO slightly supported the growth of CD34-positive cell fraction, but not CD41-positive cell fraction of MDS92 cells in combination with IL-3 or Steel factor. This cell line will be a useful tool for the study of MDS stem cells, but the mechanism of commitment of differentiation in MDS stem cells remains unknown.

Abstract 1841 PURPOSE: Despite recent advances in the treatment of multiple myeloma (MM), patients with high-risk chromosomal changes such as del13q, t(4;14) or del17p revealed significantly shorter survival. In addition, bone disease markedly reduces quality of life of the patients with MM. To overcome these problems, we have designed and screened synthetic phthalimides which significantly inhibited the growth of MM cell lines with high-risk chromosomal abnormalities. The purposes of this study are to explore novel drugs which possess anti-tumor activity against high-risk MM cells and to examine the anti-osteoclastogenic activity and to isolate directly binding molecules. METHODS AND RESULTS: Thirty synthetic phthalimides were screened for anti-proliferative effect on KMS34 cells with t(4;14) and deletion of chromosome 17. A phthalimide derivative, 2-(2,6-diisopropylphenyl)- 5-amino- 1H-isoindole- 1,3- dione (TC11) significantly inhibited growth of KMS34 cells as well as other MM cells lines with high-risk chromosomal abnormalities (IC50 to KMS34 cells= 4μM). TC11 increased annexin V fraction and induced apoptosis in a caspase-dependent manner. In vivo anti-myeloma activity was evaluated using KMS34-bearing lcr/SCID mice by intraperitoneal injection of TC11. Twenty mg/kg of TC11 significantly inhibited growth of TC11-derived tumor cells, and apoptosis of MM cells was observed by histopathological examination. In order to evaluate hematological toxicity of TC11, growth of colony-forming cells was examined. In the presence of 5μM of TC11, formation of CFCs was not suppressed, suggesting low hematopoietic toxicity. In pharmacokinetic study using lcr/SCID mice, the plasma concentrations of TC11 was examined; Cmax=18.1μM, Tmax=1.5hr, T1/2 =4.5hr when 100mg/kg of TC11 was injected, and Cmax=2.1μM Tmax=1.0hr, T1/2 =4.5hr when 20mg/kg was injected. In order to examine efficacy to bone disease, anti-osteoclastogenic activity was examined by adding TC11 to M-CSF/RANK ligand-induced osteoclastogenic culture of mouse bone marrow mononuclear cells. The number of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated osteoclasts was reduced in the presence of 1μM of TC11. It was also found that TC11 inhibited bone resorption by pit assay. We also tried to isolate directly binding proteins to TC11 by our unique in vitro selection system using mRNA display, in vitro virus (IVV) method. We identified nucleophosmin 1 (NPM1) as a TC11-binding molecule. Knockdown assay introducing siRNA for NPM1 into HeLa cells induced emergence of the cells with multipolar spindles, suggesting centrosomal disruption during cell division. Since NPM1 gene localizes at chromosome 5q, anti-MDS effect of TC11 was also examined. TC11 also inhibited growth of MDS-L cells (IC50=7μM). CONCLUSION: A novel phthalimide derivative, TC11, has anti-MM activity in vivo and is a potentially effective drug for high-risk MM with bone lesions. TC11 directly binds to NPM1 and induces apoptosis of MM and MDS cells with low toxicity to normal hematopoiesis. Disclosures: No relevant conflicts of interest to declare.

Abstract 1432 Previously we demonstrated that inhibition of anti-apoptotic BCL-2 family members sensitize leukemic cells to 5-Azacytidine (5-Aza), using siRNA and pharmacological inhibition with the BH3-mimetic ABT-737, both in vitro and ex vivo (Bogenberger, JM., et. al. ASH Annual Abstracts 2011;118:Abstract 3513). Crucially, several anti-apoptotic BCL-2 members (e.g. BCL-2 and BCL-XL) required concurrent inhibition for potent and universal sensitization to 5-Aza. Anti-apoptotic BCL-2 proteins block the execution of programmed cell death (apoptosis) by binding to and counteracting two types of pro-apoptotic BCL-2 family proteins: the “BH3-only” proteins, including both activators (BIM and BID) and sensitizers (e.g. NOXA, PUMA, HRK), and the multi-domain effector proteins (BAX and BAK). Cells dependent on anti-apoptotic BCL-2 family members for survival have been defined as “primed for death” (Certo, M., et. al. Cancer Cell 2006 May;9(5):351-65). Importantly, the priming status reflects a dependence on anti-apoptotic BCL-2 family proteins and can be characterized with the BH3 profiling functional assay. This assay measures induction of mitochondrial outer membrane permeabilization (MOMP) in response to treatment with peptides derived from BH3-only proteins (Ni Chonghaile, T., et. al. Science 2011 Nov 25;334(6059);1129-33). Thus, the unique BH3 profile associated with a specific malignant cell population, is a function of the anti-apoptotic BCL-2 family member/s contextual expression in that cell population. Based on our observations of potent 5-Aza sensitization in combination with anti-apoptotic BCL-2 protein family inhibition, we hypothesized that BH3-profiling would predict response to 5-Aza. To address the potential utility of BH3 profiling in predicting response to 5-Aza in myeloid malignancies, we assayed a broad panel of AML-derived cell lines (N=13) by BH3 profiling and correlated BH3 metrics with 5-Aza response. Identical cell line passages were assayed by BH3 profiling and in 5-Aza drug dose response assays. The cell panel comprised lines derived from AML FAB subtypes M7, M6, M5, M4, M2 and M0, as well as diverse cytogenetics such as t(11;21), t(9;11), t(4;11), t(6;11), del 5q, del 7, and a broad spectrum of mutations such as FLT3, N-RAS, CDKN2A, NPM1 and DNMT3A. The panel included a normal karyotype AML cell line (CG-SH) (Munker, R., et. al. Leuk Res 2009 Oct:33(10):1405-8) and a blastic cell line derived from a patient with MDS (MDS-L) (Tohyama, K., et. al. Br J Haematol 1994 Jun;87(2):235-42). Partition modeling using several BH3 metrics discriminates 5-Aza response with statistical significance (N=13, Mann-Whitney p2uM) AML lines. For instance, the Puma BH3 peptide alone distinguishes more sensitive from less sensitive cell lines (N=13, Mann-Whitney p=0.0046). Several more complex parameters, such as “Puma+Hrk”, “Puma+Noxa,” and “Bim+Puma+Noxa+Hrk,” also significantly discriminate 5-Aza response (Mann-Whitney p=0.0011). Using continuous variable analysis, a Puma+Hrk metric exhibited the strongest correlation with 5-Aza response (R2=0.85, p Disclosures: Pierceall: Eutropics Pharmaceuticals: Employment, Equity Ownership. Lena:Eutropics Pharmaceuticals: Employment. Mesa:Sanofi: Research Funding; Incyte: Research Funding; Lilly: Research Funding; NS Pharma: Research Funding; YM Bioscience: Research Funding. Cardone:Eutropics Pharmaceuticals: Employment, Equity Ownership.

A novel long-term cultured myeloid cell line was established from the bone marrow of a patient with myelodysplastic syndrome (MDS). This cell line, designated MDS92, proliferated in the presence of interleukin-3 or granulocyte-macrophage colony-stimulating factor and transiently in the presence of Steel factor, with a tendency for gradual maturation, and formed myeloid colonies in the semi-solid culture condition. In addition, the MDS92 cell line represented rather complicated karyotypic abnormalities including the deletion of fifth and seventh chromosomes and a point mutation at codon 12 of the N-ras oncogene. These characteristics of the MDS92 cell line are exclusively compatible with the property of preleukaemia.

Abstract 3823 Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal hematopoietic stem cell disorders characterized by ineffctive hematopoiesis. Survivin belongs to the inhibitors of apoptosis (IAP) family and inhibits apoptosis. Besides its role as IAP, Survivin appears to function as a subunit of the chromosomal passenger complex (CPC) for regulating mitosis with other CPC proteins including Aurora-B. As the CPC, Survivin and Aurora-B play an important role in the maintenance of a stable genome. Until now, there has been no report to examine whether expression of Survivin and Aurora-B kinase may be increased in CD34(+) cells prepared from the patients with MDS during disease progression. To investigate the contribution of Survivin and Aurora-B to the progression and prognosis of MDS, we evaluated the expression levels of these two genes in CD34(+) cells prepared from 57 patients with MDS and 50 patients with de novo AML using real-time quantitative polymerase chain reaction. The degree of Survivin and Aurora-B expression was highly correlated with the type of MDS, was much higher in RAEB-1, RAEB-2 and secondary AML following MDS (s-AML) compared with normal control, and increased during disease progression. Expression levels of both Survivin and Aurora-B were significantly correlated with International Prognostic Scoring System (IPSS). Furthermore, the amount of Aurora-B kinase was significantly correlated with Survivin expression in MDS and s-AML, but not in de novo AML. Interestingly, the levels of Survivin and Aurora-B were remarkably higher in patients with s-AML when compared with de novo AML. We demonstrated for the first time that high levels of Survivin and Aurora-B kinase expression are distinctive molecular feature of high-risk MDS and s-AML. Marked up-regulations of Survivin and Aurora-B Kinase may contribute to genetic instability and disease progression of MDS. Disclosures: No relevant conflicts of interest to declare.

Abstract 4842 Survivin, a new member of the inhibitor of apoptosis protein (IAP) family, has been reported to be expressed in a variety of human malignancies. We identified a novel splice variant of survivin, designated as survivin-3B. Overexpression of survivin-3B in leukemia and colon cancer cells reduced cell death after etoposide and cisplatin treatment, suggesting that survivin-3B possesses anti-apoptotic activity. Using Taqman RT-PCR and flow cytometer, we examined the expression of wt-survivin and survivin-3B in 48 patients with MDS and 55 patients with de novo AML. We found that wt-survivin and surivivin-3B are especially overexpressed in high-risk MDS and overt AML following MDS. Expression levels of wt-survivin and survivin-3B are significantly associated with higher international prognostic index score of MDS. Flow cytometric analysis also revealed that myeloblast from high-risk MDS possesses abundant expression of wt-survivin, but erythoroblast dose not. In contrast, myeloblasts from de novo AML show quite low levels of wt-survivin expression (mean expression value of de novo AML is less than 8% compared with that of high-risk MDS and overt AML). Interestingly, lack of wt-survivin expression was found in 7 patients (2 MDS and 5 AML). Instead of wt-survivin, expression of survivin-3B can be detected in these samples, suggesting that survivin-3B may play an important role as an alternative apoptosis inhibitor and mitosis regulator. Our data suggests that high levels of wt-survivin and survivin-3B expression are distinctive molecular feature of high-risk MDS and overt AML following MDS. Disclosures No relevant conflicts of interest to declare.

We compared germline transcript levels of immunoglobulin heavy chain and T cell receptor (TcR) genes in a murine hematopoietic stem cell line, LyD9, and its derivative cell lines. LyD9 cells can be induced to differentiate into at least three lineages, namely, B lymphocyte, macrophage, and granulocyte lineages. Although C mu transcripts were found in stem cells to B lymphocytes, other myeloid-committed cells also expressed significant amounts of C mu transcripts. Germline TcR transcripts did not show good correlation with differentiation potential and stages of hematopoietic cells. During this search we identified a novel germline transcript containing the JH-C microliter sequence in LyD9 and some of its derivative cells. Expression of mRNAs for immunoglobulin- and TcR-associated molecules (lambda 5, MB1 and CD3 delta) was widespread except for lambda 5 mRNA. Among three mRNAs encoding putative recombinase proteins, RAG-1 and RAG-2 mRNAs were not expressed in any cell lines tested, while RBP-2 mRNA was expressed ubiquitously.

An interleukin 3-dependent multipotential stem cell clone, LyD9, has been shown to generate mature B lymphocytes, macrophages, and neutrophils by coculture with primary bone marrow stromal cells. We report here that coculture with the cloned stromal cell lines PA6 and ST2 can support differentiation of LyD9 cells predominantly into granulocyte/macrophage colony-stimulating factor (GM-CSF)- and granulocyte (G)-CSF-responsive cells, respectively. However, these stromal cell lines were unable to support lymphopoiesis of LyD9 cells. The GM-CSF-dependent line, L-GM, which was derived from LyD9 cells cocultured with PA6 stromal cells, could differentiate into macrophages and granulocytes in the presence of GM-CSF. The L-GM line can further differentiate predominantly into neutrophils by coculture with ST2 stromal cells. The G-CSF-dependent line, L-G, which was derived from LyD9 cells cocultured with ST2 stromal cells, differentiated into neutrophils in response to G-CSF. Although the stromal cell-supported differentiation of LyD9 cells required the direct contact between LyD9 and stromal cells, a small fraction of LyD9 cells that were pretreated with 5-azacytidine could differentiate into neutrophils and macrophages without direct contact with stromal cells. These results indicate that different stromal cell lines support lineage-selective differentiation of the LyD9 stem cell and that 5-azacytidine treatment can bypass the requirement of direct contact with stromal cells, albeit with a lower frequency.

An interleukin-5 (IL-5)-dependent subclone, K-5, was established from an IL-3-dependent murine hemopoietic progenitor cell line by co-culturing with bone marrow stroma cells. K-5 cells were induced to differentiate into myeloid lineage cells by co-culturing with cloned PA6 stroma cells. By co-culturing with another cloned stroma cell (ST-2s10), K-5 cells gave rise to a factor-independent transformant cell line LT-5 which proliferated in an autocrine manner by secretion of IL-5 and produced tumors in nude mice. Molecular cloning of the IL-5 gene of LT-5 cells and the nucleotide sequencing of its 5' flanking region indicate that a transposition of an intracisternal A-particle (IAP) element to the 5' flanking region of the IL-5 gene is responsible for the constitutive expression of IL-5 mRNA of an aberrant size in LT-5 cells.

The myelodysplastic syndromes (MDS) are a heterogeneous group of clonal hematologic malignancies characterized by peripheral cytopenias, a hypercellular marrow with ineffective hematopoiesis and a propensity to progress to acute myeloid leukemia (AML). MDS is thought to arise from a primitive (CD34+) hematopoietic cell that has acquired genetic and/or epigenetic abnormalities. Risk stratification according to the International Prognostic Scoring System (IPSS) defines patient categories that correlate with survival and the likelihood of transformation to AML. Greater than 50% of individuals diagnosed with MDS are in the lower-risk groups. The importance of cytogenetics in risk stratification has been verified in several studies, but is of limited value in patients with lower-risk subtypes because approximately 50% of these patients do not have karyotypic abnormalities detectable using standard techniques. To further our biological understanding of lower-risk subtypes of MDS, and to identify potential MDS-initiating alterations in the genome, we looked for alterations in DNA extracts from purified CD34+ marrow cells from 44 MDS lower-risk patients using a submegabase bacterial artificial chromosome (BAC) array to perform whole genome comparative genomic hybridization (CGH) analyses. These studies identified numerous cryptic structural DNA alterations that were not detectable by standard cytogenetic analysis and were also not found in 15 age-matched normal controls. Although most patients tested had a normal karyotype, 23 recurring, novel copy number alterations of a median size of 0.6 megabases were identified. These included gains at 11q24.2-qter, 17q11.2 and 17q12, and losses at 2q33.1-q33.2 and 14q12. Comparison of changes in CD34+ marrow cells with DNA from CD3+ cells isolated from the same patients showed that a recurring duplication at band 17q12 was exclusive to the CD34+ cells in 2 of 3 patients. Validation of this copy number gain at chr 17q12 by FISH confirmed duplication of the locus. In addition, whole genome array CGH analysis of CD34+ marrow cells from karyotypically normal (n = 25) and abnormal (n = 15) lower risk MDS patients revealed extensive genome alterations (involving >3 Mb) correlated with poorer overall survival, and was more frequently associated with transformation to AML as compared to IPSS stratification alone. Our studies suggest that array CGH may be useful as an ancillary test to better stratify lower-risk subtypes of MDS and, at the same time lead to the identification of early mutations that contribute to disease initiation.

A protein-tyrosine kinase, Syk plays a central role in Fc-gamma receptor-mediated phagocytosis in the adaptive immune system. Here we show that Syk also makes an essential role in compliment-mediated phagocytosis in innate immunity. For this purpose, HL60 cells induced to macrophage-like with vitamin D3 and TPA and C3bi-opsonized zymosan were used as the pathogen-phagocyte system. Time-lapse microscopic observation revealed that C3bi-opsonized zymosan particles were promptly attached to and sucked into the cells but non-opsonized zymosan was not, and therefore it was indicated that our phagocytosis system is mediated by the complement receptor 3 (CR3). Syk was tyrosine-phosphorylated by the treatment with C3bi-opsonized zymosan and marked accumulation of Syk was detected around the newly forming phagosomes. To further investigate the effect of Syk on complement-mediated phagocytosis, Syk-siRNA or dominant-negative Syk (DN-Syk) was introduced into HL60 cells. Quantitative analysis by flow cytometry showed that phagocytosis was severely impaired in DN-Syk or Syk-siRNA expressing HL60 cells. To determine whether the impaired capture of zymosan is due to reduced binding to CR3 or reduced engulfment after binding, the cells were treated with a quenching reagent which discriminates fluorescent zymosan particles between inside and outside the cells. In the parental HL60 cells most of the attached zymosan particles were inside the cells, while few particles were ingested in the case of DN-Syk or Syk-siRNA expressing HL60 cells. These data indicated that Syk is required for engulfment of C3bi-opsonized zymosan but not for attachment of zymosan to CR3. To clarify the molecular mechanism how Syk affects the phagosome formation and its engulfment, the behavior of F-actin was searched microscopically. At the early stage of complement-mediated phagocytosis, marked accumulation of F-actin occurred around each phagosome and was followed by rapid depolymerization in the parental HL60 cells. In contrast, phagosomes surrounded by the accumulated actin were significantly decreased in DN-Syk or Syk-siRNA expresssing cells. These results indicate that Syk promotes actin assembly around phagosomes prior to engulfment at the early stage of the phagocytosis. As for the analysis of the downstream pathway of Syk in our phagocytosis system, RhoA-signaling was investigated. Vav-RhoA pathway was activated in HL60 cells but transfer of DN-Syk or Syk-siRNA into HL60 cells reduced the activation of Vav-RhoA signaling. Therefore Syk may act as an activator of the RhoA-pathway in phagocytosis. Our results demonstrate that Syk is required for complement-mediated phagocytosis by regulating both actin accumulation around phagosomes and RhoA-signaling harmonically and finally leads to phagosome formation and its engulfment.

Vitamin K2 (VK2) analogs, including menaquinone-4 (MK4) but not vitamin K1, effectively induce apoptosis in acute myeloid leukemia cells (AML). Apoptosis induction by VK2 is specific toward leukemia cells, and almost no effect is observed in normal hematopoietic progenitor cells (Miyazawa K, Leukemia 1999, 2000, 2001). Combined treatment with VK2 plus 1α, 25-dihydroxy-vitamin D3 (D3) dramatically enhanced differentiation of leukemia cells as compared to the cells treated with D3 alone. Concomitant with the induction of differentiation and final maturation by VK2 plus D3, the cells became resistant to various apoptotic stimuli (Funato K, Leukemia, 2002). VK2 has been shown to improve the supportive hematopoietic functions of bone marrow stromal cells (Miyazawa K, Stem Cell Dev. 2004). Since VK2 (MK4, GlakayR) has been used to treat patients with osteoporosis in Japan, its non-toxicity and safety for long-term daily administration have already been well established. Case reports demonstrating the clinical benefits of using VK2 with or without D3 for treating patients with myelodysplastic syndrome (MDS) and AML have been accumulating, i.e. improving cytopenias in refractory anemia (RA) and reduction of blast cells in AML. We performed a multicenter prospective trial to determine the therapeutic benefit of VK2 with or without D3 in MDS. Patients with RA/RCMD with low/ int-1 by IPSS received VK2 (Glakay, 45 mg/day, po) for 16 weeks. The therapeutic response was assessed according to the International Working Group Criteria. Patients who did not respond to VK2 were sequentially re-registered and received a combination of VK2 plus D3 (alfacalcidol, AlfarolR, 0.75 microgram/day, po) for 16 weeks. Patients showing response to VK2 alone or VK2 plus D3 after 16 weeks continued to receive therapy for a total of 12 months. Forty-three patients have been enrolled and 29 patients were evaluable for their response to VK2. Five patients (17.2 %) showed improvement of cytopenia (major HI-E (1), minor HI-E (2), major HI-P (3), and minor HI-P (1)). Twenty out of 24 patients who showed no response to VK2 alone subsequently received VK2 plus D3. Eleven patients were eligible for evaluation and 4 patients (36.4%) showed improvement of cytopenia in response to VK2 plus D3 (major HI-E (3), minor HI-E (1) and major HI-P (1)). Four out of 7 patients (57 %) with anemia showed hematologic response. No adverse events were observed, except for one case of skin rash (Grade I) during VK2 plus D3 therapy. These data suggest that the therapeutic response rate is improved by combined treatment with VK2 plus D3 as compared with that by VK2 monothrapy. Safety and low price also support the therapeutic benefit of VK2 with D3 for improving cytopenia in RA.

We retrospectively reviewed clinical and hematologic features of nine patients with acquired idiopathic sideroblastic anemia (AISA). Seven of them had ringed sideroblasts (RS) more than 15% of marrow nucleated cells. RS persisted in the marrow even in the remaining two patients who had a relatively low marrow erythroblasts despite RS ranging from 1/4 to half of the marrow erythroid series. However, RS declined in proportion in another two patients of the nine whose disease progressed to refractory anemia with excess of blasts (RAEB), although a high proportion of RS reappeared in one patient at the time of relapse following allogeneic marrow transplantation. A similar decline of RS concomitant with disease progression was also seen in seven additional patients with RAEB or RAEB in transformation (RAEB-t) with sideroblastic erythropoiesis. Cytogenetic abnormalities, although rare initially, became detectable either at the time of disease progression or at the worsening of anemia in AISA. These observations suggest that the majority of AISA fall in the category of myelodysplasia, and that a progressive decline in RS is part of the natural history of myelodysplasia. Closer follow-up of the proportion of RS in patients with AISA is warranted to better understand its biologic significance.

To date several factor-dependent leukemia cell lines have been established. These cell lines have greatly contributed to the analyses of cytokine-mediated cellular signaling mechanisms involved in cell proliferation, differentiation and survival. In addition, they are ideal and practical models for testing the hypothesis regarding leukemogenesis. Taken together, factor-dependent leukemia cell lines are expected to be useful for studies on cell biology and development of new cancer therapeutics.

Twenty-five patients with newly-diagnosed myelodysplastic syndromes were studied by the clonal culture method at least three times during the clinical course. Clinical outcomes of the patients were classified into: a stable disease (ten patients); subsequent leukemic transformation (eight patients) and nonleukemic death (seven patients). The growth of the marrow granulocyte-macrophage progenitors (CFU-GM) at the time of diagnosis was significantly related to the survival. In addition, sequential changes in the CFU-GM growth patterns correlated with the different clinical outcome of myelodysplastic syndromes patients.

A colony-stimulating factor(CSF)-producing tumor cell line (KX-87) was established from a patient with hepatocellular carcinoma and marked granulocytosis. This cell line formed tumors on nude mice in high frequency and the mice revealed marked granulocytosis. In clonogenic assays of human bone marrow cells, KX-87 conditioned medium (CM) supported the formation of colonies mainly consisting of neutrophilic granulocytes but had no burst-promoting activity. The molecular weight of the colony-stimulating activity (CSA) in KX-87CM was estimated about 25,000 daltons by gel filtration and a new bioassay system. In principle, a subline of murine hemopoietic cell line NFS-60 was cloned which was dependent on KX-87CM. Then the growth of this subline was examined by a rapid and sensitive colorimetric tetrazolium assay. From these results, it was concluded that the CSA which KX-87 cell line produced was G-CSF.

We added recombinant human gamma-interferon (gamma-IFN) and 1 alpha, 25-dihydroxyvitamin D3 (1 alpha, 25 (OH)2D3) to the bone marrow cells from six patients with RAEB or RAEB-T in liquid suspension cultures. After cultivation for 7 to 9 days, numerical, morphological and functional changes of the cells were assessed. gamma-IFN and 1 alpha, 25 (OH)2D3 additively suppressed cell growth, especially the number of blast cells decreased. The expression of alpha-naphthylbutyrate esterase (NBE) activity appeared to be promoted but that of naphthol AS-D chloroacetate esterase (NAE) activity was apparently suppressed by the addition of gamma-IFN and/or 1 alpha, 25 (OH)2D3. The percentage of NBT reduction-positive cells and latex-phagocytizing cells was only slightly increased by both agents. These results indicate that gamma-IFN and 1 alpha, 25 (OH)2D3 cooperate to induce monocytoid differentiation of the patients' blast cells. Combination therapy with both agents merits further study.

To evaluate the effects of recombinant G-CSF and GM-CSF on RAEB and RAEB-T cells, blast cells from 6 patients were incubated in liquid culture systems with these CSFs for 7 days, and their numerical, morphological and functional changes were assessed. Both CSFs stimulated cell growth, but decreased the proportion of blast cells in 5 of the 6 cases. Karyotypic abnormalities persisted during cultivation in some cases. The CSFs also stimualted the expression of part of the esterase activities, and a positive interaction of both CSFs was seen in part. Although CSFs had no significant effects on the ability of cells to reduce NBT or to phagocytize latex particles, the results indicated that they induce partial differentiation of blast cells. It appears that such pathological cells still retain the capacity to respond to growth factors.

We are interested to know whether expression of a lineage-specific growth factor receptor is deterministic to lineage commitment during hematopoiesis. For this purpose, we introduced the human c-fms gene into the multipotential stem cell clone LyD9 and two myeloid progenitor clones, L-GM3 and L-G3, cells that differentiate in response to granulocyte/macrophage colony-stimulating factor (GM-CSF) and granulocyte (G)-CSF, respectively. Although LyD9 cells have differentiation potential to become macrophages, c-fms transfectants of LyD9 and L-GM3 cells did not differentiate in response to human macrophage (M)-CSF. However, c-fms transfectants of L-G3 cells differentiated to neutrophils in response to human M-CSF. These results indicate that the M-CSF receptor requires a specific signal transduction pathway to exert its differentiational and proliferative effects. Furthermore, the M-CSF receptor can convey a granulocyte-type differentiation signal possibly by cooperating with the G-CSF receptor signal transduction pathway. The c-fms-transfected LyD9 cells as well as the original LyD9 cells differentiated predominantly into GM-CSF- and G-CSF-responsive cells by coculturing with PA6 and ST2 stromal cells, respectively. The results indicate that differentiation lineage is not affected by premature expression of the M-CSF receptor. Instead, the stromal cell used for coculture apparently controls lineage-selective differentiation of the multi-potential stem cell line.