Platelet aggregating activity mediated by thrombin generation in the NCG human neuroblastoma cell line.

Platelet aggregating activity of the NCG human neuroblastoma cell line was compared with that of the HL-60 human promyelocytic leukemia cell line. NCG, in intact cell suspensions and ultracentrifuged pellets, induced platelet aggregation most significantly in heparinized platelet rich plasma (PRP) containing 2.5 units/ml of heparin, but not in the presence of higher concentrations of heparin or 5 mM ethylenediamine-tetraacetate or in citrated PRP. NCG induced platelet aggregation was also inhibited by hirudin or (2R,4R)-4-methyl-1-[N2-(3-methyl-1,2,3,4-tetrahydro-8-quinolinesulfon yl)-L- arginyl]-2-piperidinecarboxylic acid (MD 805) in the same manner as that of tissue thromboplastin induced platelet aggregation. HL-60 cells did not induce platelet aggregation in our heparinized PRP assay systems; however, after treatment with neuraminidase HL-60 cells became active in aggregating platelets in either heparinized or citrated PRP. NCG demonstrated high procoagulant activity by either intact cell suspensions or ultracentrifuged pellets. The procoagulant activity of NCG was reduced in Factor VII deficient human plasma as it was in the results obtained by tissue thromboplastin. These results suggest that NCG induces platelet aggregation via thrombin generated through procoagulant activity which is shed in association with microvesicles demonstrated in the ultracentrifuged pellets. This type of platelet aggregating activity found in NCG is significantly different from that of HL-60.

Inhibition of murine melanoma experimental metastasis by recombinant desulfatohirudin, a highly specific thrombin inhibitor.

Recombinant desulfatohirudin (r-hirudin), a highly specific inhibitor of thrombin, was examined to determine whether it would inhibit production of experimental lung metastasis by B16-F10 melanoma cells. In in vitro assays using mouse plasma, the high level of procoagulant activity in B16-F10 cells was significantly inhibited by r-hirudin in a dose-dependent manner. From 15 to 120 min after s.c. administration into C57BL/6 mice, r-hirudin (10 mg/kg) markedly prolonged clotting time in a time course pattern that directly correlated with that of blood distribution of 125I-labeled r-hirudin. The production of experimental lung metastasis by B16-F10 cells was significantly inhibited by r-hirudin administered s.c. at time points ranging from 120 min before to 60 min after tumor cell inoculation with the most significant effects found in mice given r-hirudin 15 or 2 min before the i.v. injection of tumor cells. The organ distribution of [125I]IdUrd-labeled tumor cells demonstrated a clear difference in the lungs of mice treated with r-hirudin and the lungs of control mice, and these differences directly correlated with the number of lung tumor colonies found 3 weeks later. The inhibition of lung metastasis was not due to direct antitumor effects of r-hirudin. These results suggest that inhibition of coagulation events by r-hirudin significantly inhibit experimental lung metastasis during a critical time of 60 min after the entry of tumor cells into the circulation.

Reduced tumorigenicity of murine tumor cells secreting gamma-interferon is due to nonspecific host responses and is unrelated to class I major histocompatibility complex expression.

Spontaneous SP1 murine adenocarcinoma cells transfected with the murine gamma-interferon (IFN-gamma) gene expressed IFN-gamma (SP1/IFN-gamma) failed to grow in syngeneic hosts and grew in nude mice. The rejection of SP1/IFN-gamma cells was related to the amount of IFN-gamma produced and appeared to be mediated primarily by nonspecific cellular mechanisms, although some role for T-cells in the afferent arm of this response is possible. SP1 cells are H2-Kk negative but express class I antigens when producing IFN-gamma. However, class I major histocompatibility complex (MHC) expression, while likely necessary, was insufficient in itself to prevent tumor growth since secretion of greater than 64 units/ml IFN-gamma was needed to inhibit tumorigenicity while only 8 units/ml IFN-gamma could induce class I antigens. Similar results were obtained with the murine colon carcinoma CT-26, a tumor that constitutively expresses class I MHC antigens, further supporting the contention that class I MHC expression is not essential for the rejection response induced by IFN-gamma. The failure of SP1/IFN-gamma cells to protect against a challenge with parent SP1 cells argues that factors other than IFN-gamma production or class I MHC expression are needed to induce a protective response against weakly or nonimmunogenic tumor cells.

Implication of retinoic acid receptor gamma in squamous differentiation and response to retinoic acid in head and neck SqCC/Y1 squamous carcinoma cells.

Nuclear retinoic acid receptors are considered to be the mediators of most of the effects of retinoic acid (RA) on gene expression. To explore the role of RA receptor gamma (RARgamma) in the growth and differentiation of SqCC/Y1 head and neck squamous carcinoma cells, they were transfected with RARgamma sense and antisense expression vectors and stable clones in which RARgamma expression was either increased or blocked were isolated. The growth inhibitory effect of RA in monolayer culture was enhanced in the sense transfectants and decreased in the antisense ones. The ability to form colonies in semisolid medium was abolished by RA in the sense transfectants, while the antisense transfected clones exhibited heterogeneous responses. The expression the squamous differentiation markers cytokeratin K1 transglutaminase type I, and involucrin was increased in the absence of exogenous retinoid in a sense transfected clone and decreased in an antisense transfected clone. RA suppressed squamous differentiation in both types of transfectant. The expression of epidermal growth factor receptor (EGFR) was higher in the antisense and lower in the sense transfectant than in the parental cells and RA decreased EGFR mRNA level in the parental and the sense transfectant but not in the antisense transfectant. In addition activator protein-1 (AP-1) binding activity was decreased by the RA treatment in the sense clones, but not in the antisense ones. These results suggest that RARgamma mediates the effects of RA on the cell growth both in monolayer culture and in semisolid medium possibly through AP-1 suppression.

Terminal differentiation and apoptosis in experimental lung metastases of human osteogenic sarcoma cells by wild type p53.

Human SAOS-2 osteogenic sarcoma cells are not metastatic in nude mice and do not express p53. We have selected a variant line (SAOS-LM2) that is tumorigenic and metastatic in nude mice. These cells were transfected with the p53 wild-type (p53wt) or mutated (p53mut 143A) gene, whose expression was verified by reverse transcriptase PCR, cDNA sequencing, and protein immunoprecipitation. Cells were injected i.v. into nude mice, and 4 months later, the mice were necropsied. All cell lines produced a similar number of visible lung metastases, albeit of different sizes. Microscopic examination revealed that most lung metastases in mice injected with p53wt cells (but not p53mut 143A or control cells) consisted of osteoid matrix and apoptotic cells. Expression of either p53wt or p53mut 143A verified the origin of the metastases. These data suggest that transfection of SAOS-LM2 cells with p53wt is associated with in vivo induction of terminal differentiation and apoptosis that inhibit progressive growth of metastases.

Etoposide and cytosine arabinoside combination chemotherapy for refractory acute lymphocytic leukemia in childhood.

Eighteen children with refractory acute lymphocytic leukemia (ALL) who had been heavily pretreated, were treated with combination etoposide and cytosine arabinoside (ara-C) chemotherapy. Seventeen of these 18 patients were in their first to third relapses; the remaining patient had never responded to induction therapy. The drug combination of etoposide followed by ara-C was administered as an intravenous (IV) infusion twice a week for two consecutive weeks, a total of four doses. The dosage was 150 mg/m2/dose for each drug. Seven (39%) of the 18 patients attained a complete remission (CR) and three (17%) attained a partial remission (PR). Complete response was obtained in two of eight patients in first marrow relapse, and in five of nine patients in second and third relapse. Five patients achieved a CR after one course of therapy and two achieved a CR after two courses of therapy. Of three patients who had previously received teniposide, two attained a CR with this combination. The duration of these responses was brief with a median of 1 month, ranging from 0.5 to 3 months, with the exception of one case, which has been in remission for 2.5 + months. Although myelosuppression was observed, none of the patients died from infection or bleeding. Allergic reaction with fever and rash was observed in two patients. The efficacy of the etoposide and ara-C combination for refractory childhood ALL is encouraging in several current reinduction regimens.

Sequence of the promoter region of the mouse gene encoding ornithine aminotransferase.

We have isolated and sequenced the promoter region of the mouse gene (mOAT) encoding ornithine aminotransferase. A comparison of these mOAT sequences with previously reported sequences for the rat and human genes encoding OAT, rOAT and hOAT, respectively, revealed a 256-bp region flanking the transcription start point that is highly conserved between the three genes. This region contains sequence motifs resembling binding sites for general transcription factors, as well as other trans-acting regulatory proteins.

DNA sequence motifs are associated with aberrant homologous recombination in the mouse macrophage migration inhibitory factor (Mif) locus.

Homologous recombination is a precise genetic event that can introduce specific alteration in the genome. A planned targeted disruption by homologous recombination of the macrophage migration inhibitory factor (Mif) locus in mouse embryonic stem (ES) cells yielded the targeted clones, some of which had genomic rearrangements inconsistent with the expected homologous recombination event. A detailed characterization of the recombination breakpoints in two of these clones revealed several sequence motifs with possible roles in recombination. These motifs included short regions of sequence identity that may promote DNA alignment, multiple 5'-AAGG/TTCC-3' tetrameres, topoisomerase I consensus sites, and AT-rich sequences that can promote DNA cleavage and recombination. A retrovirus-like intracisternal-A particle (IAP) family sequence was also identified upstream of the Mif gene, and the LTR of this IAP was involved in one of the recombinations. Identification and characterization of such sequence motifs will be valuable for the gene targeting experiments.

Distinct mechanism of human neuroblastoma cell adhesion to fibronectin.

We investigated the adhesion of three morphologically distinct human neuroblastoma cell lines (NCG, GOTO and SK-N-DZ) to intact fibronectin, central cell binding domain fragment (CBF) and CS peptide-IgG conjugates in the fibronectin molecule. Each cell line was found to express different integrin fibronectin receptors (alpha 3 beta 1, alpha 4 beta 1 and alpha 5 beta 1), although similarly attached on intact fibronectin. To CBF, NCG attached well, while GOTO moderately and SK-N-DZ poorly attached. Only GOTO adhered to CS1-IgG. RGDS inhibited the spreading of NCG and SK-N-DZ on intact fibronectin, but it barely inhibited that of GOTO. The analysis by fluorescence-activated cell sorting (FACS) revealed that NCG expressed abundant alpha 3 beta 1 and alpha 5 beta 1, but little alpha 4 beta 1, while GOTO expressed a large amount of alpha 4 beta 1 as well as alpha 5 beta 1. SK-N-DZ was undetectable in any of these molecules, but expressed alpha v beta 1, which was identified by immunoprecipitation and immunoblotting. Polyclonal antibody to alpha v beta 3 inhibited the adhesion of SK-N-DZ but not that of NCG or GOTO on intact fibronectin. These results suggest the existence of a distinct mechanism of cell adhesion to fibronectin among human neuroblastoma cell lines. It remains to be determined if such heterogeneous adhesion properties are related to the unique metastatic character of human neuroblastoma.

Cloning and mapping the mouse Crygs gene and non-lens expression of [gamma]S-crystallin.

PURPOSE: [gamma]-Crystallins are major structural proteins of the eye lens. While other crystallins have revealed distinct non-lens functions and patterns of expression, [gamma]-crystallins have generally appeared to be the most lens-specific of the crystallins. Here we examine the mouse [gamma]S-crystallin ([gamma]S) gene and its expression. METHODS: The cDNA and gene for mouse [gamma]S were cloned and sequenced. The Crygs gene was mapped using genetic crosses. Expression patterns in mouse and cow were examined by northern blot, PCR and western blot using a specific peptide antibody. RESULTS: The Crygs gene was sequenced and mapped to mouse chromosome 16, at or near the locus for the genetic cataract Opj. Northern blots of tissues from new born mice, showed lens specific expression of [gamma]S. However, in the mature mouse eye there was, in addition, clear non-lens expression of [gamma]S. In the adult bovine eye RT-PCR shows that [gamma]S is expressed in lens, retina and cornea. A peptide antibody directed against [gamma]S detects bands of the expected size in western blots of mouse lens and in 33 day old mouse retina. CONCLUSIONS: These results suggest that [gamma]-crystallins have a non-crystallin role outside the lens, one which may predate the lens in evolutionary terms. Non-lens expression seems to increase with age in young mice, hinting that [gamma]S may have a role similar to that of a stress protein in tissues of the eye, perhaps related to accumulating insults resulting from light exposure.

Malignant histiocytosis in childhood: clinical, cytochemical, and immunohistochemical studies of seven cases.

Tissue specimens obtained at autopsy from seven childhood cases of malignant histiocytosis were studied by immunohistochemistry. Clinically, the majority of the cases showed sustained fever, hepatosplenomegaly, pancytopenia, and DIC. The pretreatment diagnosis was based on their typical clinical manifestations and bone marrow smear findings. Although three patients temporarily responded to exchange transfusion and chemotherapy, all seven patients eventually died of active disease. Postmortem examination revealed the proliferation of atypical histiocytes appearing in variable degrees of maturation in the lymph nodes, liver, spleen, bone marrow, lungs, and central nervous system. Immunohistochemical staining for lysozyme, nonspecific cross-reacting antigen (NCA), alpha 1-antitrypsin (alpha 1 AT), alpha and beta subunits of S100 protein (S100 alpha, beta), and concanavalin A receptors (ConAR) in cytoplasm demonstrated the presence of two subtypes of malignant histiocytes, ie, S100 beta+/NCA-/ConAR+ (4 cases) and S100 beta-/NCA+/ConA R+ (three cases). The results of lysozyme, alpha 1 AT, and S100 alpha staining were inconsistent. A survey of the literature disclosed that the incidence of S100 protein-positive cases in children was higher than in adults (12/21 v 5/19; chi 2, P less than .05). Further large scale investigation is necessary to confirm the independence and significance of these two subtypes of histiocytes in malignant histiocytosis.

Serum Levels of Interferon-gamma, Cytotoxic Factor and Soluble Interleukin-2 Receptor in Childhood Hemophagocytic Syndromes.

Serum levels of interferon (IFN)-gamma, cytotoxic factor (CF) and soluble interleukin-2 receptor (sIL2R) were assayed in relation to hyperferritinemia in eleven cases of malignant histiocytosis (MH), seven of virus-associated hemophagocytic syndrome (VAHS) and one of familial erythrophagocytic lymphohistiocytosis (FEL). IFN-gamma was markedly elevated (>10,000 U/ml) in 5 MH cases and only in one case of VAHS. CF was significantly elevated (> 150 U/ml) in 5 MH and 4 VAHS/FEL patients. sIL2R were remarkably elevated (> 10,000 U/ml) in 5 MH and 4 VAHS patients. In individual cases, the patterns of these parameters were quite different, suggesting the existence of a variable pathophysiology in cases with hemophagocytic syndromes. In terms of the patients' outcome, high IFN-gamma or sIL2R levels were associated with a poor prognosis while high CF appeared to be associated with a better prognosis.

Correlation of growth capacity of cells in hard agarose with successful transfection by the activated c-Ha-ras oncogene and in vivo proliferative capacity at metastatic sites.

The purpose of this study was to determine whether the degree of anchorage-independent growth of rodent or human cells in increasing concentrations of agarose correlated with successful transfection of the cells with an activated c-Ha-ras oncogene and tumorigenicity in nude mice. NIH 3T3 cells, C3H 10T1/2 fibroblasts, four clones of the murine K-1735 melanoma with different metastatic capacities and the TE85 human osteogenic sarcoma line were transfected with plasmids containing the 6.6-kilobase BamHI fragment of the mutant human c-Ha-ras gene and the neo gene, which confers resistance to neomycin (pSV2-neoEJ). Cells transfected with pSV2-neo, a plasmid containing the neo gene, served as controls. Cells from parental or transfected lines (selected by Geneticin) were plated into medium containing 0.3%, 0.6% 0.9%, or 1.2% agarose. These cells were also injected subcutaneously and intravenously into nude mice. The production of tumor cell colonies in dense agarose (greater than or equal to 0.6%) correlated with successful transfection with pSV2-neoEJ and production of experimental metastases in the lung of nude mice. We conclude that the degree of anchorage-independent growth of cells predicts successful transfection with activated c-Ha-ras oncogene and tumorigenic behavior in vivo. Thus this technique may be useful for the detection of cells transfected with transforming oncogenes.

[VP 16-213 in the treatment of acute leukemia in childhood].

Effectiveness and side effects of VP 16-213, a semi-synthetic podophyllotoxin, on acute leukemia and histiocytic medullary reticulosis in childhood was tested. Four cases of refractory acute lymphocytic leukemia, five of acute non-lymphocytic leukemia-one induction failure and 4 in remission--and a case of histiocytic medullary reticulosis were treated with a combination of VP 16-213 (Days 1-5), cytosine arabinoside (Days 1-5) and adriamycin (Day 6). None of the acute lymphocytic leukemia patients yielded a complete response; however, one of them later attained a partial response with modified intermittent administration of VP 16-213 and cytosine arabinoside. A patient with acute non-lymphocytic leukemia who had failed to attain initial remission, achieved a complete response after the second course of the treatment with increased dosages. In the four acute non-lymphocytic leukemia patients in remission, complete remission was maintained more than 4 a months. A case of histiocytic medullary reticulosis demonstrated partial response. The major toxic effects produced by this regimen were marked pancytopenia and vomiting. VP 16-213 appears to be effective for myelocytic and monocytic malignancies in childhood.

[Differentiation induction and potentiation of chemotherapy by PGE1 infusion in patients with neuroblastoma--effect of PGE1 on metastatic potential of neuroblastoma].

Combination of dibutyryl adenosine 3', 5'-cyclic monophosphate or prostaglandin E1 (PGE1) and papaverine effectively induced differentiation of neuroblastoma in mice. Two cases of human neuroblastoma with stage III and IV were administered intraaortic PGE1 infusion combined with oral papaverine and conventional chemotherapy. There were no noticeable side effects and the treatment was effective in decreasing tumor size and promoting tumor maturation in the infused area. However, distant osseous metastases were developed in both cases, during and after the PGE1 administration. They survived 30 and 17 months, respectively, from the initiation of therapy. (Jpn J Cancer Chemother 10(9): 1936-1943, 1983) These results prompted us to study the metastatic potentials of neuroblastoma. In vitro studies demonstrated that cultured human neuroblastoma cells (NB-1, GOTO, SK-N-DZ, SJ-N-KP, SJ-N-CG and SK-N-FI) aggregate human platelets with maximum aggregation ranging from 28% to 51%. Addition of PGE1 or PGD2 to PRP effectively inhibited the tumor-cell-platelet interaction, with IC50 approximately 100 nM for PGE1 and 10 nM for PGD2, respectively. In addition, 50 microM PGE1 or PGD2, 5 microM PGI2 reversed neuroblastoma-induced platelet aggregation in 4 out of 5 cell lines were studied. These findings indicate a the possible role of PGs in effective inhibition of neuroblastoma metastases in vivo. However, two cell lines (SK-N-DZ and SJ-N-CG), which had been exposed to 8.5 microM PGE1 or PGD2 for 90 min and 72 hr, respectively, retained the platelet aggregating activity which was not significantly different from that of untreated cells. We conclude that clinical application of intraaortic PGE1 in the treatment of advanced neuroblastoma has advantage in potentiation of tumor cell kill and in inducing maturation. Administered PGE1 may exert its action in two ways: in preventing tumor metastasis or possibly in enhancing the metastatic potential of neuroblastoma cells. Further refinement of these modalities including other PGs such as PGD2 or PGI2 and more detailed studies on optimal PG administration to prevent metastasis should be evaluated in future.

[Etoposide (VP 16/NK 171) and cytosine arabinoside combination chemotherapy in refractory childhood leukemia].

Combination chemotherapy consisting of etoposide and cytosine arabinoside (Ara-C) was given to 38 children with hematological malignancy. They included 18 patients with acute lymphocytic leukemia (ALL), two with non-Hodgkin's lymphoma (NHL), one with myeloproliferative disorder (MPD), and one with histiocytic medullary reticulosis (HMR), all of whom had relapsed or not responded to initial treatment. Sixteen patients with nonlymphocytic leukemia (ANLL), 13 in remission, two in relapse, and one in induction failure, were also studied. The drug combination was administered by intravenous infusion twice a week for two consecutive weeks at a dosage of 150 mg/m2 for each drug. Among the 18 patients with ALL, seven complete responses and three partial responses were achieved. Six of the seven complete responders relapsed at 0.5-3 months, and the remainder has been in remission for 2.5+ months. None of the patients with refractory ANLL, NHL, MPD or HMR achieved complete remission; however, two of three ANLL patients and one HMR patient demonstrated partial response. Among the 13 ANLL patients in remission, 9 patients have continued remission for more than 4 months with a median of 26+ months, ranging from 6+ months to 40+ months, while 4 relapsed within 4 months after the administration of this regimen. The toxic effects were tolerable. Results indicate that an etoposide and Ara-C combination is effective especially in refractory ALL in childhood.

[Clinical features and therapeutic results in 14 cases of malignant histiocytosis in childhood].

Fourteen children, 4 males and 10 females, with malignant histiocytosis (MH) were treated between July 1980 and June 1986. None of them had an affected sibling with a similar disorder. Septic-type fever was the most prominent symptom in all cases. Hepatosplenomegaly was present in 13 cases, lymphadenopathy, skin rash and jaundice in 8, pulmonary infiltration or pleural effusion on chest X-ray in 8, convulsion in 6, and renal involvement in 5 out of the 14 cases. Disseminated intravascular coagulation (DIC) was seen in 13 cases and this occurred within two weeks from onset in 6 cases. Pancytopenia, abnormal results of liver function tests, hypofibrinogenemia and hypocholesterolemia were common. The diagnosis was made for all 14 cases by characteristic clinical symptoms, signs, and bone marrow findings. In 8 cases, biopsy or autopsy specimens confirmed the diagnosis. Two patients died prior to chemotherapy. Twelve patients were treated with adriamycin, cyclophosphamide, vincristine and prednisone (ACOP). Complete response (CR) was achieved in five patients, and another two patients attained CR after subsequent treatment with other combinations including VP 16-213. These 7 complete responders are now alive and free of disease 11+ to 70+ months (median, 50+ months) from the onset of disease. All partial and non-responders died within 6 months with a median survival of 20 days. Among several clinical features as prognostic indicators, renal involvement, convulsion, and DIC occurring within 2 weeks were significantly related to poor outcome. Although MH is an aggressive disease with a poor prognosis, prompt diagnosis and early treatment with intensive systemic combination chemotherapy should further improve the outcome.

[Therapeutic effect of adjuvant combination chemotherapy in the treatment of 8 cases of childhood soft-tissue sarcoma].

The therapeutic results obtained in eight cases of childhood malignant soft-tissue sarcoma are summarized. Male to female ratio was 4:4, four were rhabdomyosarcoma and 5 were defined as Group I/II. Adjuvant combination chemotherapy was administered soon after biopsy (3 cases), or after partial or total resection (3 cases) of the primary tumor. In one case, irradiation was employed and in the remaining case, no further therapy was given after surgery. The three patients who underwent total removal of the tumor followed by adjuvant chemotherapy including adriamycin, and a patient with a partially resected intra-orbital tumor which responded well to a similar form of chemotherapy are currently alive after 26+ to 71+ months. By contrast, four patients whose tumors were too bulky to be resected responded poorly to chemotherapy and died. It must be emphasized that adjuvant chemotherapy is of limited value in the treatment of advanced childhood soft-tissue sarcoma.

[Therapeutic results in 22 cases of childhood non-Hodgkin's lymphoma treated by ACOP combination chemotherapy].

Twenty-two cases of childhood non-Hodgkin's lymphoma were treated during the past 8 years from 1979 to 1986. Median age was 7 years 4 months and the age range was from 2 years 4 months to 14 years 9 months, the male to female ratio being 18 : 4. Primary sites were common in the mediastinum (n = 7) and abdomen (n = 6) followed by submandibular lymph nodes (n = 3). According to Murphy's staging system, 7 were in stage I/II and 15 in stage III/IV. Histological studies of lymphoma tissues and blasts in the cerebrospinal fluid, pleural effusion or ascites revealed that 9 cases were lymphoblastic lymphoma while only 3 were defined as Burkitt's lymphoma. With our protocol of systemic combination chemotherapy (i.e. ACOP), intrathecal methotrexate and/or involved field irradiation, twenty-one out of the 22 cases (93%) attained complete remission and 14 patients are currently alive in continuous complete remission, with a median survival of 28+ months (range 6+ approximately 76+ months).

[Improved results of treatment in 30 cases of acute nonlymphocytic leukemia in childhood].

Thirty cases of childhood acute nonlymphocytic leukemia (ANLL) have been treated with intermittent, intensive multi-drug combinations during the past 5 years. Three patients never attained complete remission (CR) and 3 died of complications after less than one month of treatment. Twenty-four (86.7 %) attained CR with a median CCR of 26 months. The median for disease-free survival (DFS) among the total 30 cases was 15 months. Twelve out of the 24 CR patients have been disease-free for longer than 16 months, indicating significantly improved therapeutic results. Among the factors affecting prognosis, we found that patients with certain clonal abnormalities of leukemic cells and initial leukocytosis (greater than 40,000/microliter) had poor prognosis. Further revision of treatment should be considered for patients with high-risk ANLL.