Treatment of two chronic myeloid leukemia patients with V299L mutation by using nilotinib / 中国实验血液学杂志

This study was aimed to enhance clinical understanding the effect of nilotinib on CML patients with V299L mutation who were resistant to imatinib. Bone marrow specimens from 2 cases of CML with V299L mutation were collected before and after the treatment with nilotinib. ABL mutation was detected by nested reverse transcription polymerase chain reaction (PCR) followed by direct sequencing. The clinical characteristics of the two cases were analyzed. The results showed that both cases were resistant to imatinib presented V299L mutation. Out of them 1 case achieved complete haematological response (CHR) after treatment with nilotinib for 6 months and another case abstained obvious molecular response after using nilotinib for 7 month. V299L mutation of both cases was turned into negative after the treatment with nilotinib. It is concluded that the nilotinib can safely and effectively override tyrosine kinase inhibitor (TKI) resistance mediated by the V299L mutation. The safety and efficacy of nilotinib for treatment of CML patients with TKI resistance and V299L mutation are satisfactory.

Detection of serum neopterin in patients with hemophagocytic lymphohistiocytosis and its significance / 中国实验血液学杂志

This study was aimed to detect the peripheral blood serum neopterin (Npt) level in the patients with hemophagocytic lymphohistiocytosis (HLH) and to explore its significance in HLH. The enzyme-linked immunosorbent assay (ELISA) was applied to detect the serum Npt level and sCD25 level in 20 HLH patients before and after treatment and 15 healthy controls. The results indicated that the serum Npt and sCD25 levels in HLH patients were significantly higher than those in healthy controls (P < 0.0001). The serum Npt and sCD25 levels in the HLH group decreased significantly after treatment, respectively (P < 0.0001). The correlation analysis of Npt with sCD25 before and after treatment showed that they had significant correlation (r = 0.81, P < 0.05 before treatment; r = 0.65, P < 0.05 after treatment). Meanwhile, the level of serum Npt and ferritin had a significant correlation in newly diagnosed HLH patients (r = 0.55, P < 0.05). It is concluded that the serum Npt may play an important role in the HLH pathogenesis, the enhancement of Npt levels has an important significance for diagnosis and evaluation for HLH.

Efficacy of dasatinib in treatment of imatinib-resistant BCR/ABL positive leukemia / 中国实验血液学杂志

This study was aimed to evaluate the efficacy and safety of dasatinib in BCR/ABL positive leukemia patients with primary or secondary resistance to imatinib. 27 patients with primary or secondary imatinib-resistant chronic myelogenous leukemia (CML) or Philadelphia chromosome positive acute lymphocytic leukemia (Ph(+) ALL) received 100 - 140 mg/d dasatinib orally. Their overall survival and tolerance were evaluated. The results showed that the median duration of dasatinib therapy was 8 (1-66) months in the 27 imatinib-resistant BCR/ABL positive leukemia cases, with a median follow-up of 54 (3-75) months. After the dasatinib treatment, 88.8% of all the 27 cases achieved complete hematologic response (CHR), 29.6% of them achieved major cytogenetic response (mCyR), 37% of all achieved complete cytogenetic response (CCyR) and 18.5% cases achieved major molecular response (MMR). Patients who received dasatinib in progress of disease (CML-AP, CML-BC and bone marrow relapse Ph(+) ALL) had a lower CCyR rate than those in stable disease (CML-CP and bone marrow remission Ph(+) ALL) (P = 0.0377), and 3 - 4 grade adverse events occurred more frequently in progress of disease than that in stable disease. Overall survival of the patients who achieved CCyR after dasatinib therapy was statistically longer than those who did not achieve CCyR (63 m vs 9 m, P = 0.0126). The most common grade 3 - 4 adverse events during dasatinib therapy including hematology events such as thrombocytopenia (51.8%), neutropenia (48.1%), anemia (33.3%), and non-hematologic events such as pleural effusion (18.5%), pulmonary infection (18.5%), pericardial effusion (11.1%). The 3-4 grade adverse events occurred within 12 months from dasatinib therapy, and were mainly observed in patients with progress of disease. It is concluded that dasatinib is an effective drug in imatinib-resistant BCR/ABL positive leukemia patients, the better curative effect and better tolerance has been observed in patients who received dasatinib in stable disease.

SRSF2 mutation in patients with chronic myelomonocytic leukemia / 中华血液学杂志

<p><b>OBJECTIVE</b>To investigate SRSF2 mutations in patients with chronic myelomonocytic leukemia (CMML) and the clinical characteristics of patients with SRSF2 mutants.</p><p><b>METHODS</b>In this study, the frequency of SRSF2 mutation in a cohort of 20 patients with CMML was detected by polymerase chain reaction (PCR) followed by direct sequencing to couple with their clinical features.</p><p><b>RESULTS</b>Of 20 patients, 4 patients were found harboring SRSF2 mutations, including 2 P95L, 1 P95H and 1 P95R point mutations. There were no significantly statistical differences in terms of their clinical characteristics between mutant and wild type group.</p><p><b>CONCLUSION</b>SRSF2 mutation was not frequently occurred in CMML patients and might associated with poor prognosis. It might be a practically diagnostic maker and therapeutic target in CMML.</p>

Detection and clinical features of MLL gene rearrangement in adult patients with acute leukemia / 中国实验血液学杂志

This study was purposed to investigate the incidence of mixed lineage leukemia (MLL) gene rearrangement and partner gene types as well as the clinical features and prognosis of acute leukemia (AL) with this rearrangement through detection in adult AL using combination of 3 techniques, and to evaluate the clinical value of this combination detection. The MLL gene rearrangement in 183 cases of adult AL was detected by combination of conventional cytogenetics, split signal FISH and multiplex nested PCR. The results showed that the incidence of MLL rearrangements in adult patients with AL was low (8.2%), and MLL-AF4 fusion gene was most common and predominant in acute lymphoblastic leukemia (ALL), while the MLL-AF6 and MLL-AF9 were most frequent in acute myeloid leukemia (AML). Extramedullary involvements were found in 40% of MLL-rearranged AL patients, and 33.3% of patients with MLL-rearranged AL reached to complete remission within 30 days during induction chemotherapy. In addition, in this cohort of MLL-rearranged adult AL patients, the 3-month relapse rate and 6-month overall survival rate were 50.0% and 50.0% respectively. It is concluded that the rate of missed diagnosis of CC technique for patients with MLL-rearranged AL reached to 60% in this study, while the combination of CC, FISH and multiplex nested PCR has been confirmed to have important significance for evaluating prognosis and conducting clinical therapy of patients with MLL-rearranged AL.

Analysis of DNMT3a gene mutations in acute myelogenous leukemia / 中国实验血液学杂志

This study was purposed to investigate the mutational status of DNA methyltransferase (DNMT3a) gene and the clinical features of AML patients with DNMT3a mutations. Using PCR combined with directly sequencing, the somatic mutations of DNMT3a involving residue of amino acid 882 were detected in 77 AML patients. Furthermore, the clinical features of these patients were also studied. The results showed that the DNMT3a mutation were detected in 7 out of 59 patients with de novo AML (11.9%), which included 4 patients with DNMT3a R882C, 2 patients with DNMT3a R882H and 1 patient with DNMT3a Y874C. Morphology examination indicated that 2 patients were M(2), 1 patient was M(4) and 4 patients were M(5). Cytogenetic analysis revealed that karyotype in 5 out of 7 patients with DNMT3a mutation were normal. In total of 27 patients with normal karyotype 5 patients (22.7%) were found harboring DNMT3a mutation, while no DNMT3a mutation was found in 21 patients with abnormal karyotype. The mutation rate in patients with positive CEBPA was obviously higher than that in patients with negative CEBPA (p = 0.002). Immunophenotype analysis showed that 4 patients (4/7, 57.1%) with DNMT3a mutation expressed lymphoid antigens including CD4 or/and CD7. There were no statistical significance in age, gender, blast cells of bone marrow, white blood cell and platelet counts, hemoglobin level, ratio of CR, mutations of FLT3-ITD, NPM1 and c-kit between patients with DNMT3a mutation and patients with wild DNMT3a (p > 0.05). It is concluded that the DNMT3a mutations are more prevalent in AML patients with normal karyotype accompanying with positive NPM1 and/or CEBPA mutation, the role of DNMT3a mutation in AML prognosis needs to be further studied.

Isocitrate dehydrogenase gene mutations in acute myeloid leukemia / 中国实验血液学杂志

The purpose of this study was to identify point mutation of the isocitrate dehydrogenase gene (IDH1 and IDH2) in patients with acute myeloid leukemia(AML) and its clinical significance. 90 de novo AML patients were selected for this study, the genomic DNA was served as template, the exon4 of IDH1 and IDH2 were amplified respectively. The IDH mutation was detected by using directly sequencing method for PCR product. The results indicated that among 90 de novo AML patients, 4 patients (4.4%) showed the IDH1 gene mutation positive, and 7(7.8%) patients showed IDH2 gene mutation positive. None was found harboring both mutations, the overall rate of mutation positive of them was 12.2%. In the AML patients with IDH gene mutation positive, the rate of normal karyotype was 72.7%, which was significantly higher than that in abnormality karyotype. The CR rate in mutation positive patients was 72.7%, which seemed as if higher than that in mutation negative patients, but without statistical significance. The mutation disappeared when the patients gained CR, and reappeared in same loci after relapse occurred. It is concluded that the IDH gene point mutation appears in normal karyotype patients, especially in patients combined with NPM1 gene mutation. The IDH gene mutation may be an important target for therapy and evaluating clinical prognosis of patients with normal karyotype.

Clinical analysis of 10 cases of secondary hemophagocytic lymphohistiocytosis treated with HLH-2004 chemotherapy / 中国实验血液学杂志

This study was aimed to investigate the therapeutic efficacy of HLH-2004 chemotherapy in patients with secondary hemophagocytic lymphohistiocytosis (sHLH). 10 cases of sHLH treated with HLH-2004 regimen at our department were analyzed retrospectively. The results showed that 7 patients had clinical response to HLH-2004 regimen, while other 3 patients had no clinical response. 5 cases did not complete initial therapy of 8 weeks. Out of 5 cases, 4 died in the process of chemotherapy, 1 patient abandoned for serious side effects but finally acquired remission following 4 cycles of CHOP regimen. 5 cases underwent the whole courses of initial therapy. Out of 5 cases, 3 patients acquired remission, and other 2 were not well controlled. Out of the 3 patients who had achieved remission, one died of relapse, and other 2 patients kept remission. Out of the 2 patients who were not well controlled, one patient died, but another patient acquired remission after being discharged. It is concluded that patients with infection-associated hemophagocytic syndrome (IAHS) have high rates of remission after receiving HLH-2004 regimen combining with effective antibiotics. However, patients with HLH secondary to EBV (EBV-HLH) or lymphoma (LAHS) have low rates of remission or are easy to get relapse after remission.

A case of myelodysplastic syndrome with aberrant evolution of chromosome 1 and 11 in 6 years of follow-up / 中国实验血液学杂志

This study was aimed to investigate the relationship between cytogenetic evolution and disease progression in patient with MDS-RAEB. By a long term (6 years) follow-up of a patient with MDS-RAEB, peripheral blood cell count, bone marrow cell morphology and conventional cytogenetics were monitored regularly. In addition, fluorescence in situ hybridization (FISH) was applied to confirm the aberrant karyotype. The results indicated that this patient was failed with conventional chemotherapy of AML, but had response to ATRA and 6-MP in the 72 months follow-up. At initial diagnosis, the cytogenetics analysis showed normal karyotype, whereas 46, XY, 2q+[1]/46, XY[19] was found at 48 months, 46, XY, dup(1q)[3]/46, XY[7] at 56 months, and dup (1) as well as der (11) with complex karyotype at 68 months, which was accompanied by progressive decrease of platelet count. It is concluded that karyotype evolution is perhaps associated with progression of MDS.

Analysis of CEBPA mutation in acute myeloid leukemia / 中国实验血液学杂志

In order to evaluate the incidence of CCAAT/enhancer binding protein alpha (cebpa) gene mutation in patients with acute myeloid leukemia (AML), 22 AML patients with normal karyotype (NK-AML) were enrolled in this study, including de novo AML and relapsed AML. The cebpa gene was amplified by 2 stages using genomic DNA as template, the cebpa gene mutation amplified product was detected by direct sequencing or clone sequencing. The results showed that the cebpa mutations including deletion and insertion were found in 4 out of 22 AML patients (18.2%) and all of these 4 patients were M(2). Two patients had N-terminal nonsense mutation and the other two had C-terminal in-frame mutation. It is concluded that PCR combined with direct sequencing and clone sequencing can be used to detect cebpa mutations. cebpa mutations are mainly identified in M(2) subtype of NK-AML patients, its significance for prognosis needs to further investigate.

Mutation of tet2 gene and malignant blood disease / 中国实验血液学杂志

Tet2 (the 2nd member of tet oncogene family) is a newly discovered antioncogene on the chromosome 4q24 of the patient with malignant myeloma, which has a potential for functional deletion. Recent studies demonstrated that tet2 mutation was found in polycythemia vera (PV), essential thrombocythemia (ET), myelofibrosis, systematic mastocytosis (SM), and myelodysplastic syndrome (MDS). However, a great number of perspective researches are still needed for exploring the role of tet2 in the pathogenesis of malignant blood diseases. In this review, the relation of tet2 mutation with myeloproliferative neoplasm, systemic mastocytosis, myelodysplastic syndrome, acute myeloid leukemia and other malignant blood diseases are summarized.

Clinical study on 10 cases of pancytopenia selectively treated by cyclosporine a / 中国实验血液学杂志

This study was aimed to explore the effect and adverse reaction of cyclosporine A (CsA) in treatment of pancytopenia without reticulocyte decrease but with elevated LDH. 10 patients were selected according to our standards and were treated by CsA. The curative effect and adverse reaction of patients were evaluated by following up for 6 - 116 months. The effect of CsA in the maintenance treatment of AA patient with an obvious rise of LDH was illustrated by means of typical case. The results indicated that 10 patients had different diagnosis, but had similar clinical and laboratory characteristics. Among them, 9 patients showed a relatively good curative reaction to CsA. Treatment of 1 patient was stopped because of pneumonia tuberculosis. It is concluded that the elevated LDH without reticuleocyte decrease may be a biomarker to predict the curative reaction to CsA for patients with pancytopenia. Selectively treating pancytopenia with CsA can obtain a higher curative reaction and maintenance treatment with CsA is an important factor for reducing recurrence of this disease.

Molecular markers related to prognosis of acute myeloid leukemia-review / 中国实验血液学杂志

Numerous genetic abnormalities which can not be identified by cytogenetic detection (e.g., gene mutations, gene expression abnormalities) have been gradually found, which means that the further molecular classification of AML (acute myeloid leukemia) with distinctive prognosis have arrived. For example, mutations of the transcription factor (CCAAT enhancer binding factor alpha, C/EBPalpha) or nucleophosmin-1 (NPM1) may predict better prognosis, whereas partial tandem duplications of the MLL gene (MLL-PTD), internal tandem duplications of FLT3 (FLT3-ITD) or mutations of WT1 gene confer worse prognosis. This review focuses on the features and relationship of these genetic abnormalities, as well as their influence on the prognosis of AML.

FMS-like tyrosine kinase 3 gene mutations in acute myeloid leukemia / 中国实验血液学杂志

This study was aimed to investigate the frequency of FMS-like tyrosine kinase 3 (FLT3) mutations including internal tandem duplication (ITD) mutation of juxtamembrane region and point mutation of the second tyrosine kinase domain (TKD) in acute myeloid leukemia (AML) patients and its clinical significance. The ITD mutation in FLT3 exon 14, 15 of bone marrow mononuclear cells was detected by genomic DNA-PCR, the TKD point mutation in FLT3 exon 20 was detected by genomic DNA-PCR combined with restriction endonuclease digest. The results indicated that among 131 newly diagnosed AML patients, 21 patients (16.0%) showed FLT3-ITD positive, 3 patients (2.3%) showed FLT3-TKD positive. None was found harboring both mutations. The WBC and bone marrow blast counts in FLT3-ITD positive patients seemed both higher than those in patients with wild-type FLT3 (FLT3-wt), but there was significant difference only in WBC count (p<0.05). The complete remission (CR) rate in FLT3-ITD positive patients was 47.6%, which was significantly lower than that in FLT3-wt patients (88.1%, p<0.05). There was no statistical difference in CR rate between FLT3-ITD positive and negative patients in 20 cases of M3; the CR rate in FLT3-ITD positive patients with non M(3) was 37.5 (6/16) which was obviously lower than that in FLT3-wt patients with non M3 (90.6%, 48/53) (p<0.05). 3 FLT3-ITD positive patients with CR relapsed after CR for 14 (2-20) months with relapse rate 50% (3/6) which was higher than that in FLT3-wt patients (29.2%, 14/48). It is concluded that FLT3 mutation is common in AML patients, while FLT3-ITD mutation is more frequent than FLT3-TKD mutation. The AML patients with FLT3-ITD mutation have a poor prognosis, while FLT3-TKD point mutation does not significantly influences prognosis of the patients. Therefore early detection of FLT3 mutation may be important for targeting therapy and evaluating clinical prognosis of AML patients.

Low-dose cytarabine and aclarubicin in combination with granulocyte colony-stimulating factor priming in 50 patients with relapsed acute myeloid leukemia / 中国实验血液学杂志

To evaluate the efficacy and toxicity of low-dose cytarabine and aclarubicin in combination with granulocyte colony-stimulating factor (G-CSF) protocol for patients with relapsed acute myeloid leukemia (AML). A total of fifty relapsed patients have been enrolled, including 13 early relapsed and 37 late relapsed. 24 patients were male and 26 were female, with age ranging from 15 to 69 (median 47) years. Out of them, 7 patients relapsed after allogeneic peripheral blood stem cell transplantation (allo-PBSCT), 3 patients relapsed after autologous peripheral blood stem cell transplantation (auto-PBSCT), 25 patients relapsed after received regimens including high dose cytarabine and 15 patients relapsed after CR or stopping chemical therapy themself in course of consolidatory therapy. 30 relapsed patients received CAG regimen, and 20 patients (control group) received an anthracycline in combination with cytarabine. The results indicated that after one course, the complete remission (CR) rate was 46.7% (14/30), the CR rate after allo-PBSCT was 50% (3/6), the early death rate was 3.3% in CAG group; and CR rate was 30% (6/20) and the early death rate was 15% in control group. Myelosuppression was mild to moderate, and no severe nonhematologic toxicity was observed in two groups. The overall median times in CAG group and control group were 22 and 19 months respectively. In conclusion, CAG regimen as the induction therapy is effective and well tolerable with low side effects for relapsed patients who had received high dose cytarabine, auto-PBSCT or allo-PBSCT.

Tyrosine kinase mutation and acute myeloid leukemia with T (8; 21) / 中国实验血液学杂志

This study was aimed to investigate the status of c-KIT, Fms-like tyrosine kinase 3 (FLT3) and Janus kinase 2 (JAK2) mutations in acute myeloid leukemia (AML) patients with t (8; 21) and to analyze their relation to clinical feature and prognosis. PCR, AS-PCR, restriction and sequencing methods were used respectively to detect the FLT3, JAK 2 and c-KIT mutations in 8 cases of de novo AML with t (8; 21) and 6 cases of relapsed AML with t (8; 21). The results showed that the c-KIT mutation was found in 2 cases out of 14 AML patients with t (8; 21) (14.3%), among them 1 case had c-KIT D816V mutation, the other had c-KIT D816Y mutation. The FLT3-ITD mutation was detect in 1 out of 14 patients (7.1%), but JAK2 mutation could not be detected in all 14 cases. In conclusion, tyrosine kinase mutation relates to AML with t (8; 21), patients with tyrosine kinase mutation may have higher relapse, extramedullary infiltration and poor prognosis. The screening c-KIT, FLT3 mutations may play an important role in evaluating prognosis and guiding treatment of t (8; 21) AML.

The application of fluorescence in situ hybridization in detecting chronic myeloid leukemia / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To evaluate the clinical significance of the application of fluorescence in situ hybridization (FISH) in detecting chronic myeloid leukemia (CML).</p><p><b>METHODS</b>Chromosome preparation was made by using 24-hour culture. FISH technique using dual color dual fusion (DC-DF) BCR/ABL probe was performed in all 158 cases and R-banding was also employed for karyotyping in some patients.</p><p><b>RESULTS</b>Among the 158 cases, 98 cases were Ph positive, of which 69 cases (70.4%) were typical FISH pattern (1R1G2F), the other 29 cases (29.6%) showed 12 different types of atypical FISH pattern. The most frequent atypical patterns found were 1R1G1F in 7 cases (7.1%), 2R1G1F in 5 cases (5.1%), 1R1G2F and 1R1G3F in 4 cases (4.1%), 2R2G1F in 3 cases (3.1%). Karyotype analysis on 18 CML cases with atypical FISH patterns demonstrated that the atypical FISH patterns were due to variant translocation in 3 cases; the additional third signal was because of a supernumerary Ph chromosome. The karyotyping results did not conform to FISH results in four cases suggesting the conceivable mistakes in karyotyping. The 1R1G1F signal pattern seen in 3 cases with classical t(9;22) resulted from the deletion of derivative chromosome 9. The 1R1G2F signal pattern detected in 40% to 64% of interphase cells of 3 cases without Ph chromosome by conventional cytogenetic analysis suggested a submicroscopic translocation. Three cases treated with Glivec or bone marrow transplantation showed normal karyotypes with a small amount of BCR/ABL positive cells by FISH detection.</p><p><b>CONCLUSION</b>FISH technique is of great value for the diagnosis of CML and confirmation of variant translocation, occult Ph translocation, derivative chromosome 9 deletion, therapeutic effect of interferon and Glivec as well as detection of minimal residual disease after bone marrow transplantation.</p>

Analysis of chromosome karyotype abnormality in acute myeloid leukemia / 中国实验血液学杂志

This study was aimed to investigate the characteristics of chromosome karyotype abnormality in patients with acute myeloid leukemia. 379 cases of de novo acute myeloid leukemia were enrolled in this study. Chromosome preparations were made on bone marrow cells by using direct method or short-term culture. Chromosome karyotypes were analyzed by R-banding technique. The results indicated that 216 out of 379 patients had clonal chromosome aberrations with the percentage of 56.99%, including 19 kinds of balanced translocations and 70 kinds of chromosome gain or loss. The most common structure and numerical abnormalities were t(15;17) and -Y with the percentage of 25.86% and 5.80%, respectively. -Y was accompanied by t(8;21) in 90.9% of the -Y abnormality cases, which accounted for 40.81% of t(8;21) positive cases. The abnormality of M(3) was significantly higher than the other FAB subtypes (p < 0.05). No significance was found between the male and female groups for the chromosome aberrations (p > 0.05). In conclusion, some specific chromosome aberrations are correlated with specific FAB subtype, which may contribute to the clinical diagnosis and subtyping of the disease.

Cytogenetic analysis of 362 cases of chronic myeloid leukemia / 中国实验血液学杂志

In order to evaluate the cytogenetic features and clinical significance of chronic myeloid leukemia (CML), chromosome preparation of bone marrow cells was made by using 24-hour culture, and R-banding technique was employed for karyotyping in 362 patients with CML. The patients were divided into two groups of chronic phase (CP) and blast crisis (BC). The results showed that the incidence of additional chromosome, variant translocation and Philadelphia (Ph) negative, bcr/abl positive CML with abnormal chromosomes in CP group were 70 cases (26.1%), 19 cases (7.1%), 4 cases (1.5%), and were 50 cases (53.2%), 8 cases (8.5%), 4 cases (4.3%) in BC group. Among the 362 cases, 324 cases (89.5%) were Ph positive. Classic translocation was found in 297 cases (91.7%) and variant translocation in 27 cases (8.3%), including 13 cases of simple variant, 13 cases of complex variant and 1 case of marked Ph. Special karyotypes were found in 120 out of 362 cases. Analysis of these karyotypes demonstrated that the most common numerical abnormalities were +Ph (21.7%), +8 (10.0%), +21 (10.0%), +19 (7.5%) and structure abnormalities were i(17q) (13.3%). In conclusion, compared to chronic phase, the incidence of additional chromosome, variant translocation and so on are much higher at in blast crisis. It is feasible to evaluate the progress of the disease by karyotype analysis.

Immunophenotypic features in 143 cases of acute promyelocytic leukemia / 中国实验血液学杂志

This study was aimed to investigate the immunophenotypic characteristics of acute promyelocytic leukemia (APL). CD45/Side Scatter (SSC) gating strategy and multiparametric flow cytometry were used to determine immunophenotype of 143 patients with APL. The immunophenotypic features were compared between newly diagnosed APL patients and relapsed APL patients. 42 patients with HLA-DR(-) (non-APL AML, DR(-)AML) were randomly selected as controls. 31 out of 42 AML patients were CD34 negative, and their immunophenotypes were compared with those in newly diagnosed APL patients. The results showed that (1) CD34 and HLA-DR were both negative in 91.9% of newly diagnosed APL, while the positive rate of CD34 and HLA-DR elevated in relapsed cases (3.0% vs 37.5%, 3.9% vs 37.5%). The positive rate of CD34 in HLA-DR(-) AML group was higher than that in newly diagnosed APL group (23.4% vs 3.0%). The positive level of CD34 in newly diagnosed APL group was lower than that in HLA-DR(-) AML group; (2) the positive rate of CD33 in newly diagnosed APL group was higher than that in other groups (97.0% vs 75.0%, 83.3%, 83.9%), as well as the the positive level of CD33 (p < 0.05). (3) no lymphoid antigen other than CD2 was expressed in newly diagnosed APL group. The positive rate of CD7 was 9.5% in DR(-) AML group and 6.5% in CD34(-)/DR(-) AML group, both were higher than those of newly diagnosed APL group (p < 0.05). It is concluded that the immunophenotyping can provide proof to the rapid diagnosis of APL. For those patients with DR(-) AML, it may be helpful to identify APL depending on following features: low or negative CD34 expression, homogeneous and bright expression of CD33, no lymphoid antigens other than CD2, higher SSC.