B regulatory cells and monocyte subpopulations in patients with chronic graft-vs-host disease.

AIM: To assess the correlations of B regulatory cells (Bregs) and monocyte subsets in peripheral blood with the National Institutes of Health (NIH)-consensus-defined clinical manifestations of chronic graft-vs-host disease (cGvHD), in an attempt to establish their role as cellular biomarkers. METHODS: This multidisciplinary prospective study enrolled adult cGVHD patients treated in the University Hospital Center Zagreb and University of Zagreb School of Medicine. Immunophenotypic subpopulations of CD24highCD38high Bregs (CD27-, CD27+, and total) and monocyte (classical, intermediate, and non-classical) counts were correlated with demographic, transplant, and cGVHD-related data. Bivariate correlation analysis was performed to evaluate the correlations between Bregs and monocytes subsets and cGVHD organ involvement, as well as cGVHD severity and immunosuppression intensity. RESULTS: Twenty-two adult patients (54.5% female) with cGVHD were enrolled. The median (range) age was 44.5 years (24-65). All patients were transplanted for hematologic malignancies and 40.9% had severe NIH cGVHD global score. The median time from cGVHD diagnosis to the analysis was 16.6 months (0-176). The organ most frequently affected with cGVHD were the eyes (68.2%), skin (45.5%), lungs (45.5%), and liver (40.9%). Lower total and CD27-Bregs counts were correlated with worse cGVHD severity, higher immunosuppression intensity, and lung cGVHD, in terms of cell count, but also with skin cGVHD, in terms of percentages. Patients with liver and joint/fascia cGVHD had a lower percentage of non-classical monocytes and patients with more severe global NIH score had a higher classical monocytes count. CONCLUSION: Different organs affected by cGVHD are differently associated with different subpopulations of Bregs and monocytes.

Influence of flavonoids' lipophilicity on platelet aggregation.

Flavonoids are natural polyphenolic compounds present in a wide spectrum of plants that have a beneficial effect on human health. In the context of cardiovascular diseases related to plaque and thrombus formation, flavonoids exhibit an anti-aggregatory effect. Previously, it has been reported that all tested flavonoids exhibit an antiaggregatory effect on platelet aggregation when measured by impedance aggregometry on whole blood, in the test of aggregation induced by adenosine diphosphate (ADP). As not all flavonoids have the same targets within signaling pathways, an assumption of a common non-specific mechanism related to lipophilicity is to be considered. To test this hypothesis, reverse-phase thin layer chromatography was used to assess the lipophilicity of flavonoids; impedance aggregometry was used for testing of platelet aggregation and flow cytometry to monitor the influence of flavonoids on platelet activation. Lipophilicity analysis showed a highly negative correlation of logP and MINaAC for groups of flavones and flavanones. As determined by flow cytometry, the exposition of receptors necessary for the promotion of platelet activation and primary clot formation was diminished, i.e., lowered expression of the activated form of integrin αIIbß3 was observed in the presence of flavanone. Platelet membrane stabilization by flavonoids as a mechanism of antiaggregatory effect has been supported by impedance aggregometry experiments when specific inhibitors of platelet aggregation signaling pathways (U73122, indomethacin, verapamil) were used in the presence of a weak (ADP) and a strong (TRAP-6) agonist of aggregation. While individual flavonoids can have specific targets within aggregation signaling pathways, all flavonoids share a common non-specific mechanism of platelet aggregation inhibition related to their lipophilicity and membrane stabilization that, to some extent, contributes to their antiaggregatory effect.

Results of the European survey on the assessment of deep molecular response in chronic phase CML patients during tyrosine kinase inhibitor therapy (EUREKA registry).

PURPOSE: The advent of tyrosine kinase inhibitor (TKI) therapies has revolutionized the treatment of chronic myeloid leukemia (CML). The European LeukemiaNet (ELN) recommends quantification of BCR-ABL1 transcripts by real-time quantitative PCR every 3 months during TKI treatment. Since a proportion of patients in deep molecular response (DMR: MR4, MR4.5, MR5) maintain remission after treatment stop, assessment of DMR is crucial. However, systematically collected molecular data, monitored with sensitive standardized assays, are not available outside clinical trials. METHODS: Data were collected on the standardized assessment of molecular response in the context of real-life practice. BCR-ABL1 transcript levels after > 2 years of TKI therapy were evaluated for DMR by local laboratories as well as standardized EUTOS laboratories. Since standardized molecular monitoring is a prerequisite for treatment discontinuation, central surveillance of the performance of the participating laboratories was carried out. RESULTS: Between 2014 and 2017, 3377 peripheral blood samples from 1117 CML patients were shipped to 11 standardized reference laboratories in six European countries. BCR-ABL1 transcript types were b3a2 (41.63%), b2a2 (29.99%), b2a2/b3a2 (3.58%) and atypical (0.54%). For 23.72% of the patients, the initial transcript type had not been reported. Response levels (EUTOS laboratory) were: no MMR, n = 197 (6.51%); MMR, n = 496 (16.40%); MR4, n = 685 (22.64%); MR4.5, n = 937 (30.98%); MR5, n = 710 (23.47%). With a Cohen's kappa coefficient of 0.708, a substantial agreement between EUTOS-certified and local laboratories was shown. CONCLUSIONS: Multicenter DMR assessment is feasible in the context of real-life clinical practice in Europe. Information on the BCR-ABL1 transcript type at diagnosis is crucial to accurately monitor patients' molecular response during or after TKI therapy.

Influence of Blood Count, Cardiovascular Risks, Inherited Thrombophilia, and JAK2 V617F Burden Allele on Type of Thrombosis in Patients With Philadelphia Chromosome Negative Myeloproliferative Neoplasms.

INTRODUCTION: Thrombosis is the most common complication in Philadelphia chromosome negative (Ph-) myeloproliferative neoplasms patients. PATIENTS AND METHODS: In a cohort of 258 Ph- myeloproliferative neoplasm patients, the difference between patients with and without thrombosis was analyzed according to genetic thrombophilia factors, JAK2 V617F status and burden allele, blood count, cardiovascular risk factors and age. Patients were also divided in polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) subgroups as well as by the type of thrombosis. RESULTS: Analysis of cardiovascular risk factors regarding arterial thrombosis showed that PV patients with thrombosis had higher incidence of diabetes (P = .030), ET patients more often had hypertension (P = .003) and hyperlipidemia (P = .005), while PMF patients had hyperlipidemia (P = .046) and at least one cardiovascular risk factor (P = .044). Moreover, leukocytes > 18 × 109/L and V617F burden allele > 25.7% were statistically significantly different in PV patients (P = .019 and borderline significant at P = .055, respectively), while in ET patients leukocytes > 9.2 × 109/L (P < .001) and age at diagnosis of > 55 years were statistically significantly different (P = .002). PMF patients with V617F burden allele ≤ 34.8% were more prone to thrombosis (P = .032). When comparing patients with and without venous thrombosis, cutoff value of V617F burden allele > 90.4% was significant for PV patients with thrombosis (P = .036), as was > 56.7% for PMF patients with thrombosis (P = .046). Platelets ≤ 536 × 109/L and age at diagnosis > 54 years showed statistically significant difference for ET patients with thrombosis (P = .015 and P = .041, respectively). CONCLUSION: On the basis of our results, a new scoring system for thrombosis risk in PV could be made, while PMF prognostic model may be expanded for better recognition of potential thrombotic risk factors.

The incidence of atypical patterns of BCR-ABL1 rearrangement and molecular-cytogenetic response to tyrosine kinase inhibitor therapy in newly diagnosed cases with chronic myeloid leukemia (CML).

BACKGROUND: To analyze the frequency of atypical fluorescence in situ hybridization signal patterns and estimate the complete cytogenetic response (CCyR) and major molecular response (MMR) during 12 months of tyrosine kinase inhibitor therapy in patients with newly diagnosed chronic myeloid leukemia. METHODS: The study included bone marrow and peripheral blood samples from 122 patients with newly diagnosed chronic myeloid leukemia. Detection of the breakpoint cluster region-Abelson fusion gene (BCR-ABL1) was performed using fluorescence in situ hybridization with a dual-color dual-fusion translocation probe, and MMR analysis was performed using the real-time quantitative polymerase chain reaction method. RESULTS: Variant translocation was determined in 10 samples and a deletion on the derivative chromosome 9 (del/der(9)) was found in 20 samples. The rates of CCyR and MMR were similar between patients with reciprocal translocation, variant translocation, deletion of derivative BCR, or ABL1-BCR fusion gene. The Kaplan-Meier test did not show any significant differences in the rates of CCyR and MMR among those groups of patients. CONCLUSION: The frequencies of variant translocation and del/der(9) in the present study agree with the results of other studies performed worldwide. No differences were observed in the rates of CCyR and MMR between patients with atypical patterns and reciprocal translocation.

Serum chitotriosidase: a circulating biomarker in polycythemia vera.

OBJECTIVES: Serum chitotriosidase activity (CHIT1) is a biomarker of macrophage activation with an important role in inflammation-induced tissue remodeling and fibrosis. Macrophages have been described to play a crucial role in regulating pathological erythropoiesis in polycythemia vera (PV). The aim of this study was to evaluate CHIT1 in patients diagnosed with Philadelphia-negative myeloproliferative neoplasms (MPNs). METHODS: Using fluorometric assay, we measured CHIT1 in 28 PV, 27 essential thrombocythemia (ET), 17 primary myelofibrosis (PMF), 19 patients with secondary myelofibrosis and in 25 healthy controls. RESULTS: CHIT1 was significantly higher in PV (p < .001) and post-PV myelofibrosis (MF) transformation (post-PV MF) (p = .020), but not in ET (p = .080), post-ET MF transformation (p = .086), and PMF patients (p = .287), when compared to healthy controls. CHIT1 in PV was positively correlated with hemoglobin (p = .026), hematocrit (p = .012), absolute basophil count (p = .030) and the presence of reticulin fibrosis in the bone marrow (p = .023). DISCUSSION: A positive correlation between CHIT1 and these distinct laboratory PV features might imply macrophages closely related to clonal erythropoiesis as cells of CHIT1 origin. In addition, a positive association between CHIT1 and reticulin fibrosis might indicate its potential role in PV progression. CONCLUSION: CHIT1 might be considered as a circulating biomarker in PV. Additional studies are needed to clarify the role of CHIT1 in promoting disease progression and bone marrow fibrosis in PV.

Comparison of Branded and Generic Imatinib Plasma Concentrations in Patients With Chronic Myelogenous Leukemia: Unicentric Study.

INTRODUCTION: For over a decade, imatinib has been the first-line treatment of Philadelphia chromosome-positive chronic myeloid leukemia (CML). Doubts on the bioequivalence and bioavailability of emerging generic compounds have been expressed. Adequate imatinib plasma concentration ([IPC] ≥1000 µmol/L) is associated with a better chance of optimal treatment response in patients with CML. In this study, we compared the achieved IPCs between the branded compound and its 2 generic forms. PATIENTS AND METHODS: IPCs were compared in 24 consecutive patients with CML in the first chronic phase who changed from branded to generic imatinib. The median age was 49 years (range, 22-76 years). Fifteen of them were male. Six patients were switched to Neopax, 13 to Imakrebin, and 5 patients received both generics consecutively. All compounds were used in an equivalent dose of 400 mg orally once daily for at least 1 month before plasma concentrations were measured. High-performance liquid chromatography was used to determine imatinib plasma concentration from a specimen collected 21 to 24 hours after the last dose. RESULTS: The median IPC achieved with branded imatinib was 1454 µmol/L (range, 485-2707 µmol/L) with 18 patients (75%) having IPC ≥ 1000 µmol/L. For Neopax and Imakrebin, median IPCs were 1717 µmol/L (range, 1249-3630 µmol/L) and 1458 µmol/L (range, 707-880 µmol/L), respectively, with 11 of 11 (100%) and 16 of 18 (89%) patients having IPC ≥ 1000 µmol/L. No significant difference in measured IPCs between all 3 compounds was found (P > .257). CONCLUSION: When taken at equivalent doses, imatinib generics are bioequivalent and comparable in clinical efficacy and have the potential for substantial savings in the treatment cost for CML.

Prognostic significance of constitutive phosphatidylinositol 3-kinase/Akt and mitogen-activated protein kinase phosphorylation in acute myeloid leukemia.

Acute myeloid leukemia (AML) is a malignant hematopoietic disease with poor clinical course and outcome. There is a constant need for new prognostic factors that could facilitate patient risk stratification. The aim of our research was to determine the phosphorylation levels of phosphatidylinositol 3-kinase (PI3K)/Akt and mitogen-activated protein kinase (MAPK) pathways in leukemic cells, their relation to P-glycoprotein (P-gp) expression/activity and their prognostic significance in adult de novo AML. A total of 118 patients with AML were enrolled in the study. In a multivariate Cox regression analysis we found that P-gp activity and Akt phosphorylation were independent poor prognostic factors of overall survival (OS). In contrast, phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2) represented a favorable prognostic factor of OS and relapse-free survival (RFS). A negative correlation between P-gp activity and p38 phosphorylation level was found, implying a possible role of this MAPK pathway in P-gp regulation. In addition, we found correlation between Akt and p38 phosphorylation levels, indicative of co-activation of two signaling cascades in AML.

Spontaneous perforation of the small intestine, a novel manifestation of classical homocystinuria in an adult with new cystathionine beta-synthetase gene mutations.

The clinical picture of classical homocystinuria is diverse. This is the first report of an adult homocystinuric patient with non-traumatic spontaneous small bowel perforation. A 47-year old man presented with abdominal rebound tenderness, hypotension and tachycardia, anemia, and elevated markers of inflammation. Other routine laboratory tests were normal. Abdominal x-ray showed no free air. An emergency laparotomy revealed jejunal perforation in the left upper quadrant. Histologic specimen showed full-thickness nonspecific inflammation of the intestinal wall with granulocytic infiltration, hemorrhage and necrosis. Tuberculosis, actinomycosis and typhus were histologically and clinically excluded. After excluding all known possible causes of perforation, we presumed a causative relationship between homocystinuria and small bowel perforation. It could be hypothesized that connective tissue weakness in homocystinuria is a result of homocysteine interference with recombinant human fibrillin-1 fragments or cross-linking of collagen through permanent degradation of disulfide bridges and lysine amino acid residues in proteins. DNA analysis showed three detectable mutations in the cystathionine beta-synthetase gene, 1278T:c.833T>C, and two new mutations, V372G:c.1133T > G, and D520G:c.1558A > G in the aternatively spliced exon 15.

Bone morphogenetic protein-7 expression is down-regulated in human clear cell renal carcinoma.

BACKGROUND: Recent studies demonstrated that the expression pattern of bone morphogenetic protein-7 (BMP-7) is altered in different tumors. We determined expression of BMP-7 in human clear cell renal carcinoma (CCRC). METHODS: Samples from cancer and corresponding healthy tissue were obtained from 20 patients who underwent nephrectomy for CCRC. Expression of BMP-7 mRNA was determined by reverse transcriptase polymerase chain reaction (RT-PCR), and protein expression was analyzed by immunohistochemistry. RESULTS: RT-PCR showed strong down-regulation of BMP-7 mRNA in cancer tissue. Immunohistochemistry revealed expression of BMP-7 in normal renal tissue, with almost complete loss of BMP-7 expression in malignant cells of 6 patients (30%). After 3 years of follow-up, 5 out of 6 patients with high BMP-7 mRNA expression were alive and disease-free, compared with 9 out of 14 patients with low BMP-7 mRNA expression. CONCLUSIONS: BMP-7 mRNA and protein expression were down-regulated in CCRC. Further prospective studies are needed to characterize the role of BMP-7 in human CCRC.

Pre-B-cell acute lymphoblastic leukemia with bulk extramedullary disease and chromosome 22 (EWSR1) rearrangement masquerading as Ewing sarcoma.

We report a 2-year-old female with a subcutaneous tumor who was initially misdiagnosed as suffering from Ewing sarcoma with a positive EWSR1 rearrangement and EWS/FLI1 transcript. After finding lymphoblasts in peripheral blood, the diagnosis of acute lymphoblastic leukemia was established. This necessitated further analysis of the subcutaneous tumor. The tissue was positive for immature B-cell markers and an immunoglobulin heavy chain gene rearrangement, which confirmed the final diagnosis of common type acute lymphoblastic leukemia with bulk extramedullary disease. The patient was treated with chemotherapy and was in remission 30 months after the diagnosis.

Immunolocalization and mRNA expression of bone morphogenetic protein-6 in human clear cell renal carcinoma.

Bone morphogenetic proteins (BMPs) are members of the transforming growth factor-beta superfamily of proteins. Dysregulation of BMP signaling has been suggested in the carcinogenesis of different organs. We determined BMP-6 mRNA and protein expression in localized human clear cell renal carcinoma (CCRC), obtained from 20 patients who underwent nephrectomy, by the real-time polymerase chain reaction and immunohistochemistry. 15/20 patients exhibited higher BMP-6 mRNA expression in malignant than in healthy renal tissue relative to the PBGD expression (p < 0.05). Immunostaining intensity for BMP-6 in healthy renal tissue ranged from 0 to 2 (average 0.9), as well as in renal clear cell carcinoma (average 1.1). Seven of 20 (35%) healthy tissue samples failed to stain with BMP-6 antibody, compared to 2/20 (10%) tumor samples (p < 0.05). BMP-6 immunostaining was positive in 18/20 CCRC samples. Staining was localized in the cytoplasm and/or membrane of malignant cells. Malignant tissue had significantly higher BMP-6 mRNA expression than healthy tissue. There was no significant correlation between BMP-6 mRNA and protein expression with disease presentation, disease progression and patients' characteristics. Long-term follow-up of our patients is needed to determine the possible role of increased expression of BMP-6 in CCRC.

[Anagrelide for treatment of patients with essential thrombocythaemia]. / Anagrelid u lijecenju bolesnika s esencijalnom trombocitemijom.

Anagrelide is an imidazokinazoline derivate that reduces platelet production by interfering with megakaryocyte proliferation and maturation. As a non-cytostatic drug it selectively affects megakaryocyte lineage and therefore anemia and leukocytopenia are not likely to occur. This makes anagrelide adequate for the treatment of chronic myeloproliferative disorders characterized by marked thrombocytemia. In this study we have evaluated efficacy of anagrelide in 14 pretreated patients with essential thrombocytemia. The response was achieved in 11 patients (78%) and was defined as a platelet count lower than 450 x 10(9)/l or 700 x 10(9)/l without thrombohemorrhagic incidents. The therapy was stopped in 6 patients; three patients did not respond to treatment; one had a serious side effect; pregnancy was the reason for discontinuation of therapy in one patient, and in one patient therapy was changed by his own request. We can conclude that anagrelide is an effective and safe drug for pretreated patients with essential thrombocythemia.

[Cytomorphology of acute mixed leukemia]. / Citomorfologija akutnih mjesovitih leukemija.

UNLABELLED: Biphenotypic acute leukemias (AL) with blasts expressing both myeloid and lymphoid antigens are grouped with undifferentiated AL and bilineal AL in the group of AL of ambiguous lineage. Not all AL with myeloid and lymphoid antigens (ALMy+Ly) are true biphenotypic AL. According to EGIL scoring system, true biphenotypic ALMy+Ly are those with a sum of antigens 2 or more points for both myeloid and lymphoid lineage or for B and T lineage. The aim of this study was to compare cytomorphology and immunophenotype of AL to better understand the relation of certain AL morphology, immunophenotype, cytogenetics and molecular biology of biphenotypic AL. PATIENTS AND METHODS: The study included a group of 169 AL patients treated from 1985 till 1991, and a group of 102 AL patients treated from 1993 till 1996 at Zagreb University Hospital Center. Bone marrow and peripheral blood of the two groups of AL patients were analyzed according to Pappenheim (May-Grunwald-Giemsa), cytochemical and alkaline phosphatase-anti-alkaline phosphatase (APAAP) immunocytochemical staining. Flow cytometry immunophenotyping of bone marrow was also done in both patient groups. RESULTS AND DISCUSSION: In the group of 169 adult AL patients, 116 were cytomorphologically classified as acute myeloblastic leukemias (AML), 35 as acute lymphoblastic leukemias (ALL) and 18 as acute undifferentiated leukemias (ANLM). In 6 (3.4%) of 169 AL patients, blasts expressed both myeloid and lymphoid antigens. In the group of 102 AL patients there were 19 (18.6%) ALMy+Ly. In 64 patients cytomorphologically classified into AML subgroup out of 102 AL patients, there were 15 (14.7%/102; 23.4%/64) AML with lymphoid antigens (AMLLy+). In 35 patients cytomorphologically diagnosed as ALL and 3 as ANLM out of 102 AL, there were 4 (3.9%/102; 10.5%/38) ALL with myeloid antigens (ALLMy+). The incidence of mixed AL in 102 AL was more consistent with other studies, pointing to the necessity of myeloperoxidase (MPO), CD7 and TdT determination as part of standard immunophenotyping for better recognition of mixed AL. CONCLUSION: In both groups of 169 and 102 AL patients, the majority of AL cases were cytomorphologically classified as AML. In the group of 169 patients there were 5 AMLLy+ and in the group of 102 patients there were 15 AMLLy+. In one ANLM,My+ out of 169 AL and also one ANLM,My+ out of 102 AL, blasts were cytomorphologically undifferentiated; in 3 ALLMy+ of 102 AL blasts expressed lymphoid morphology. According to EGIL scoring system, among 15 AMLLy+ of 102 AL there were 4 true biphenotypic ALMy+Ly (1 M1, 2 M3, 1 M4), and in 4 ALMy+Ly with undifferentiated and lymphoid morphology there were 2 true biphenotypic AL (1 L2; 1 ANLM). In 3 ALLB+T out of 35 ALL, one was interlineal biphenotypic AL. These observations are consistent with other studies and WHO determinations indicating that the majority of true biphenotypic leukemias are associated with immature monoblastic or myeloid cytomorphology or with lymphoid or undifferentiated characteristics, but may also express any AML cytomorphology type. Thus, there is no direct correlation of leukemic cell cytomorphology and biphenotypic AL immunophenotype.

[Current approach to diagnosis and treatment of acute leukemia in adults]. / Suvremeni pristup dijagnostici i lijecenju akutnih leukemija u odraslih.

Current classification of acute leukemia is based on morphology, immunophenotyping, cytogenetic and molecular abnormalities of leukemic cells. All these techniques have a diagnostic and prognostic value. Molecular abnormalities in many cases suggest the pathogenesis of acute leukemia, but also point to the key site of genetic abnormalities that may be targeted with the therapy. Treatment approach in acute leukemia is still chemotherapy. The probability of long-term disease-free survival after intensive chemotherapy for younger patients with acute lymphoblastic leukemia and acute myeloid leukemia is 30%-40% and 40%-50%, respectively. Allogeneic stem cell transplantation is associated with better disease-free survival compared to other cytotoxic regimens. In recent years, targeted therapy seems to improve the chemotherapy outcome. This therapy targets only leukemic cells while sparing normal cells. Immunotherapy, differential agents and especially drugs acting on the key molecular abnormalities are currently being used together with chemotherapy as a treatment approach for acute leukemia. It is expected that techniques such as gene expression profiling will identify genetic abnormalities and their proteins as a targeted site for new drugs. This might increase the efficacy of leukemia treatment and control.

[Treatment of chronic myeloid leukemia with imatinib in the accelerated stage of the disease]. / Lijecenje kronicne mijeloicne leukemije u uznapredovaloj fazi bolesti imatinibom.

Philadelphia chromosome positive chronic myeloid leukemia (Ph+ CML), in advanced stage of disease, is resistant to standard chemotherapy. Imatinib was found to be effective in these patients. This paper shows our preliminary results. Imatinib mesylate was given to 15 patients during a 9-month period. Nine of them were in accelerated phase and 6 in blastic crisis of Ph+ CML. Patients were evaluated for hematologic and cytogenetic responses. Imatinib mesylate induced complete haematologic response in 12 patients (80% and cytogenetic response in 8 patients (53%). Six patients (40%) had a major cytogenetic response. After a 9-month follow up Ph+ CML progressed in 9 patients (60%) and 4 of them died. The most frequent adverse effects were edema, nausea, neutropenia and thrombocytopenia. Imatinib mesylate has a substantial, but short term activity in the accelerated phase and blastic crisis of the Ph+ CML.

Acute promyelocytic leukemia M3: cytomorphologic, immunophenotypic, cytogenetic, and molecular variants.

Acute promyelocytic leukemia (APL) M3 is an acute myeloid leukemia (AML) subtype characterized by proliferation of malignant promyelocytes with mature myeloid immunophenotype and the translocation t(15;17)(q22;q11), which results in the fusion of retinoic acid receptor-alpha (RARalpha) gene on chromosome 17 and the gene PML on chromosome 15. There are three M3 morphologic variants: the typical hypergranular form and the microgranular and basophilic variants. Although most leukemic cells in M3 patients express t(15;17), other cytogenetic abnormalities have also been reported. Also, there are three molecular variants of the PML/RARalpha transcript (bcr1, bcr2, bcr3). Blasts had typical hypergranular appearance (13 patients) with a mature myeloid immunophenotype (HLA-DR(-),CD13(+), and/or CD33(+)) (10 patients) in the majority of patients with M3 followed in this study. The typical translocation [t(15;17)(q22;q11)] was detected by cytogenetic analysis in 5 M3 patients, but PML/RARalpha was positive in 13 out of 15 patients, as assessed by RT-PCR (8 patients with bcr1 and 5 with bcr3 subtype). Cytogenetic diversity was found in three patients (1 with t(17;17), 1 with +8, and 1 with add (7)(q22); -7; +8). According to many studies, leukemic cell heterogeneity in APL influences the clinical outcome of disease. The analysis of certain leukemic cell characteristics on the clinical outcome in our study revealed that patients with bcr3 had shorter medians of first remission and survival in comparison to patients with the bcr1 isoform of PML/RARalpha. Also, the clinical relapse of disease in 4 APL patients with reverted PML/RAR alpha positivity is consistent with the view that detection of PML/RARalpha by RT-RCR in patients in remission implies a poor prognosis. On the contrary, lack of detection of PML/RARalpha by RT-PCR at least three times is a sign of long remission and survival.