Dysregulation of miRNA in Leukemia: Exploiting miRNA Expression Profiles as Biomarkers

Micro RNAs (miRNAs) are a class of small non-coding RNAs that have a crucial role in cellular processes such as differentiation, proliferation, migration, and apoptosis. miRNAs may act as oncogenes or tumor suppressors; therefore, they prevent or promote tumorigenesis, and abnormal expression has been reported in many malignancies. The role of miRNA in leukemia pathogenesis is still emerging, but several studies have suggested using miRNA expression profiles as biomarkers for diagnosis, prognosis, and response to therapy in leukemia. In this review, the role of miRNAs most frequently involved in leukemia pathogenesis is discussed, focusing on the class of circulating miRNAs, consisting of cell-free RNA molecules detected in several body fluids. Circulating miRNAs could represent new potential non-invasive diagnostic and prognostic biomarkers of leukemia that are easy to isolate and characterize. The dysregulation of some miRNAs involved in both myeloid and lymphoid leukemia, such as miR-155, miR-29, let-7, and miR-15a/miR-16-1 clusters is discussed, showing their possible employment as therapeutic targets.

Correlation of Calcium and Magnesium Levels in the Biological Samples of Different Types of Acute Leukemia Children

Acute leukemia (AL) is a common childhood malignancy. It is clinically and morphologically heterogeneous. The present work was intended to estimate the concentration of calcium (Ca) and magnesium (Mg) in serum and whole blood samples of children having AL; 1- to 5- and 6- to 10-year-old children age group was chosen of both genders. Healthy children of the same age group were selected as controls for comparative study. For sample pretreatment, a microwave-assisted acid digestion (MAD) was carried out, to assess the concentration of Ca and Mg in biological samples of AL children. The MAD method was validated by analyzing Clinchek® Control certified samples of whole blood and serum. Ca and Mg were analyzed in the digested samples by flame atomic absorption spectrometry (FAAS). The results showed significantly higher concentration of Ca, whereas lower contents of Mg in the serum and whole blood of AL children in both genders, as compared to healthy subjects. The data provide assistance to physician/clinicians and other professional staffs to investigate the imbalance of minerals in biological samples of AL children.

Preclinical pharmacokinetics and pharmacodynamics of DCLL9718A: An antibody-drug conjugate for the treatment of acute myeloid leukemia

Few treatment options are available for acute myeloid leukemia (AML) patients. DCLL9718A is an antibody-drug conjugate that targets C-type lectin-like molecule-1 (CLL-1). This receptor is prevalent on monocytes, neutrophils, and AML blast cells, and unlike CD33, is not expressed on hematopoietic stem cells, thus providing possible hematopoietic recovery. DCLL9718A comprises an anti-CLL-1 IgG1 antibody (MCLL0517A) linked to a pyrrolobenzodiazepine (PBD) dimer payload, via a cleavable disulfide-labile linker. Here, we characterize the in vitro and in vivo stability, the pharmacokinetics (PK) and pharmacodynamics (PD) of DCLL9718A and MCLL0517A in rodents and cynomolgus monkeys. Three key PK analytes were measured in these studies: total antibody, antibody-conjugated PBD dimer and unconjugated PBD dimer. In vitro, DCLL9718A, was stable with most (> 80%) of the PBD dimer payload remaining conjugated to the antibody over 96 hours. This was recapitulated in vivo with antibody-conjugated PBD dimer clearance estimates similar to DCLL9718A total antibody clearance. Both DCLL9718A and MCLL0517A showed linear PK in the non-binding rodent species, and non-linear PK in cynomolgus monkeys, a binding species. The PK data indicated minimal impact of conjugation on the disposition of DCLL9718A total antibody. Finally, in cynomolgus monkey, MCLL0517A showed target engagement at all doses tested (0.5 and 20 mg/kg) as measured by receptor occupancy, and DCLL9718A (at doses of 0.05, 0.1 and 0.2 mg/kg) showed strong PD activity as evidenced by notable reduction in monocytes and neutrophils.

In Vitro Function of Chronic Myelocytic Leukemia Granulocytes. Effects of Irradiation and Storage

Granulocyte function was studied in 9 patients with untreated, Ph1-positive chronic myelocytic leukemia (CML). The nitroblue tetrazolium reduction by stimulated granulocytes was impaired in all patients; 4 patients also had diminished phagocytosis and 2 others defective Chemotaxis. In spite of this variety of polymorphonuclear (PMN) functional impairments, there is little evidence of increased susceptibility to infections in CML patients. This suggests that CML-PMN leucocytes (PMNs) may be successfully used for transfusion into neutropenic recipients, as previously reported. To evaluate the effects of irradiation and liquid storage on CML-PMNs, 5 of our patients were subjected to leukapheresis by continuous-flow centrifugation in the Aminco Celltrifuge, and granulocyte functional capacities were also evaluated on the cell-rich plasma immediately after collection and after short-term storage at 4°C with or without irradiation (1500 rads). As evaluated by in vitro studies, granulocytes maintained, even after irradiation, functional activities similar to those found immediately after collection up to 24 h of storage at 4°C and presented a moderate loss of function after 48 h. Chemotaxis appeared to be the most sensitive detector for cellular damage of stored leucocytes, irradiated and non-irradiated, so that it might be used for assessment of leucocyte function before transfusion.

Preliminary Observations on Intravenous Idarubicin (4-Demethoxydaunorubicin) in the Chronic and Accelerated Phase of Chronic Myelogenous Leukemia

The study included 13 patients with chronic myelogenous leukemia (8 in the chronic phase with high WBC counts at onset, and 5 in the accelerated phase, poorly responding to conventional drugs for the chronic phase). They were treated with 4-demethoxydaunorubicin (idarubicin), a new anthracycline analog more active than daunorubicin (DNR) and doxorubicin (DX) in experimental tumor models which offers a higher therapeutic index than existing anthracyclines. Idarubicin was administered i.v. at the dose of 8 mg/m2 on days 1, 3 and 5. All patients in the chronic phase (8/8) developed significant leukopenia. Five of these 8 patients showed complete reduction of splenomegaly, and 4 of hepatomegaly as well. In all the other cases, hepato-splenomegaly was reduced by more than 70%. Three of the 5 patients in the accelerated phase of chronic myelogenous leukemia also showed massive cytolysis. More important, all of them showed complete or major reduction of hepato-splenomegaly and renewed responsiveness to conventional drugs for the chronic phase of the disease. Idarubicin was fairly well tolerated by all patients with only minor gastrointestinal side effects and no liver damage or acute cardiotoxic effects. These findings indicate that idarubicin – although it cannot replace established drugs for the chronic phase of the disease – represents an added therapeutic resource for producing rapid cytolysis at onset and, above all, in the accelerated phase of chronic myelogenous leukemia.

Phenotypic and Ultrastructural Profile of M5 Leukemia Cells in Peripheral Blood and Skin Infiltrate

The leukemic cells circulating in the peripheral blood and invading the skin of a patient with type M5 myelomonocytic leukemia were compared using ultrastructural, cytochemical and immunological criteria. Neoplastic cells exhibited more differentiated morphologic features in the skin than in peripheral blood, resembling tissue macrophages. The cytochemical pattern did not show any appreciable difference, whereas the surface antigenic profile was dissimilar. Most circulating leukemic cells were Leu M1+ and Leu M3+, and the percentage of OKM1+ and OKIa-1+ cells varied in two different blood samples examined. Conversely, OKIa-1 monoclonal antibody stained viritually all the leukemic cells infiltrating the skin in the absence of any appreciable reactivity with the other monoclonal antibodies. The phenotype of the malignant cells in the skin did not vary during the clinical course of the disease. These observations suggest that the cutaneous microenvironment is able to induce leukemic cells to mutate their phenotypic features towards a more mature state, or that only relatively differentiated circulating leukemic cells are able to leave the bloodstream and colonize the skin.

Studies on Granulocyte Functions in Patients with Chronic Myeloid Leukemia

Granulcoyte functions, viz. endocytosis, NADPH oxidase activity and iodination by leukocytes, were studied in granulocytes isolated from 17 chronic myeloid leukemia (CIVIL) patients at initial diagnosis (stage I), from 10 patients in relapse (stage II), and 10 patients in acute blastic crisis (stage III). The mean phagocytic index of granulocytes from CML patients was similar to the normal value. NADPH activity decreased as the disease progressed. Thus, the amount of formazan produced was lower in granulocytes from patients in stage II (P < 0.05) and stage III (P < 0.01) than that produced by normal granulocytes. H2O2-Myeloperoxidase-dependent iodination was found to be significantly reduced in granulocytes from all stages of the disease compared to that of normal, stage I (P < 0.01), stage II (P < 0.05) and stage III (P < 0.01). It thus seems that granulocyte function becomes less efficient as the disease progresses towards acute blastic crisis. Immature cells from the same patients carried out these functions at a more reduced level than did their mature counterparts.

A Specific Spontaneous Leucocyte Cycle in Chronic Myelogenous Leukemia

Cyclic leukocytosis has been previously described in patients with chronic myeloid leukemia (CML). The purpose of this report is to call attention to the possibility of a specific long-term cycle of approximately two months in CML, on the basis of the reported patients studied prospectively with no treatment and to describe an additional case with similar changes. Kinetic studies suggest that the leucocyte oscillation observed would reflect variation in cell production. Implications of the findings with regard to pathogenesis and therapy of the disease are discussed. A long-term cycle of the neutrophil count, showing a period of approximately two months, was also found in eight children with acute myelogenous leukemia (AML) in remission, analyzed retrospectively.

The Diagnostic Value of Serum Copper Levels and other Hematochemical Parameters in Malignancies

An increase in the serum copper (Cu++) level has been described as a sensitive index of disease activity in several hematologic and nonhematologic malignancies. In order to explore the diagnostic value of Cu++ compared to other hematochemical parameters frequently abnormal in malignancies, Cu++, serum α2 globulin (α2), plasmatic fibrinogen (Fibr), the erythrocyte sedimentation rate (ESR), and serum iron (Fe++) have been detected and evaluated in 267 patients affected with the following diseases: Hodgkin's lymphoma (HL), non-Hodgkin's Lymphomas (NHL), Acute Leukemias (AL), Chronic Myeloid Leukemia (CML), Chronic Lymphocytic Leukemia (CLL), Myeloma (MM), and Breast Cancer (BC). The best correlation between Cu++ increase and disease activity has been found in HL, NHL, AL, and BC. In these diseases, when the considered parameters were compared, Cu++ and ESR showed a similar pattern, i.e., a high frequency of abnormalities in active disease. It is concluded that Cu++ represents a good complement to some other aspecific parameters in evaluating the activity and diffusion of neoplasias and the therapeutic results, particulary in HL, NHL, AL and BC.

Correlation of Fundus Lesions and Hematologic Findings in Leukemic Retinopathy

This prospective study evaluated the relationship between the fundus findings in leukemic retinopathy and hematologic parameters. Seventy-four newly diagnosed consecutive patients with acute leukemia were included, 49 with acute myelocytic leukemia (AML), and 25 acute lymphocytic leukemia (ALL). Blood parameters were based on data obtained before starting any therapeutic modalities. Leukemic retinopathy was detected in 32 patients (43%). Patients with ALL and retinal hemorrhages had significantly lower hemoglobin and hematocrit levels than those without hemorrhages (p = 0.004 and 0.018 respectively). AML patients with white-centered hemorrhages had a significantly higher leukocyte count than those without (p = 0.0002). ALL patients with cotton-wool spots had significantly lower hemoglobin levels and hematocrit than patients without such lesions (p = 0.044 and 0.05 respectively). AML patients with cotton wool spots had significantly lower leukocyte and platelet counts than those without (p = 0.019 and 0.003 respectively). Our results suggest that anemia is related to the findings of retinal hemorrhage and cotton-wool spots in ALL patients, that high leukocyte count is associated with white centered hemorrhage in AML patients, and that thrombocytopenia is not associated with retinal hemorrhage in this group of patients.

Growth and responsiveness of human granulocytic leukemic cells in vitro

Cells from patients with acute myeloid leukemia (AML) and chronic myeloid leukemia (CML) can be grown and their properties analyzed in agar gel cultures. Levels of the glycoprotein regulator colony stimulating factor (CSF) were found to be elevated in 19-66% of plasmas tested from patients with various types of granulocytic leukemia, and the growth of AML and CML cells in vitro was observed to be dependent on, and responsive to, stimulation by CSF-containing material. In both diseases, the leukemic cells appear to be in a responsive state with respect to normal growth regulators, and potentially alterations in regulator levels may therefore be able to achieve sustained arrest of the growth of leukemic populations.

Proliferation and maturation of human leukemia cells in liquid culture

Bone marrow from patients with acute myelogenous leukemia (AML), acute myelomonocytic leukemia (AMML), chronic myelogenous leukemia (CML), preleukemia, and from healthy volunteers was cultured using a recently developed liquid diffusion technique. Differential and viable cell counts and 3H-thymidine labeling indices were performed at intervals up to 30 days. Differentiation was assessed morphologically by light and electron microscopy, histochemically, and by functional tests for phagocytosis and the presence of surface receptors for IgG. Colony-stimulating activity (CSA) was assayed against normal human bone marrow by the agar colony technique. In acute leukemia cultures, viable cell counts usually fell within the normal range. However, most AML cells failed to demonstrate significant maturation in vitro, and did not produce detectable CSA. In AMML cultures, maturation was defective but some differentiated macrophages were observed and the cells produced high concentrations of CSA. Preleukemic cultures demonstrated normal growth but maturation was impaired as evidenced by a high percentage of immature cells during the first 7 days. CML cultures showed abnormally high growth capacity resulting in viable cell counts 2-3 times normal. In the chronic phase of CML, maturation was qualitatively normal and the cells produced CSA. With the onset of blast transformation, maturation became abnormal but growth remained high. These studies support a concept of AML as a primary defect in cellular maturation and of CML as a primary abnormality of proliferation. The production of CSA by neoplastic cells relates to the degree of monocyte-macrophage differentiation within the leukemic population. Human preleukemia is characterized by a failure of normal maturation in vitro.

Leukapheresis in management hyperleucocytosis induced complications in two pediatric patients with chronic myelogenous leukemia

Complications caused by elevated white blood cell count in pediatric patients with CML could be a presenting feature of the disease. Here, we present two adolescents, aged 16 and 17years, who were admitted for investigation of extremely elevated leukocytes and complications of leucostasis. Initial manifestations were priapism and blurred vision, respectively. Diagnosis of chronic phase of chronic myeloid leukemia is established, and conventional measures for leucoreduction began. However, since there were no improvements, a leukapheresis procedure was initiated. After undergoing 3 daily procedures the leukocyte count declined for each patient, with resolution of pripaism and ophtalmological disturbances. Leukapheresis is safe and effective therapeutic option for patients with complications of hyperleucocytosis. If started in a timely manner, permanent organ damage or death could be avoided.

Nucleolar and cytoplasmic RNA density-concentration in leukemia granulocytic progenitors in human bone marrow biopsies: A short cytochemical note

The present study was undertaken to provide more information on the differentiation and maturation of human granulocytes using computer-assisted image RNA densitometry at single-cell level. The bone marrow of patients suffering from chronic phase of chronic myeloid leukemia represents a very convenient model for such measurements because of the satisfactory number of early stages, as well as advanced stages, of the granulocytic cell lineage represented by neutrophils. In contrast to the erythroid cell lineage, similar nucleolar and cytoplasmic RNA density-concentration values were found only in early granulocytic progenitors such as myeloblasts and promyelocytes. In advanced stages of the granulocytic development starting with myelocytes, these cells were characterized by a larger decrease in the cytoplasmic RNA concentration in comparison with that of the nucleoli. Thus, the nucleolar to cytoplasmic RNA concentration ratio in these cells was above 1. On the other hand, it should be pointed out that late differentiation stages of granulocytes, starting with myelocytes, possessed nucleolar bodies (nucleoli without surrounding perinucleolar chromatin) of a markedly reduced size.

[Fundamental study of blood and bone marrow]

The WHO classification incorporated recent advances of immunology, cytogenetics, and molecular biology, which developed from FAB classification based on cell morphology and cytochemistry. One of the most distinct changes was "AML with recurrent genetic abnormalities." The immunological and cytogenetic studies are required to apply the classification to hematopoietic and lymphoid neoplasms in addition to conventional examinations of the blood and bone marrow. The fundamentals of specimen collection, cell counts, morphologic analysis of blood cells, special stains and other laboratory studies were described in related to the management of myeloid leukemias.

Identification of a Circulating Soluble Form of CD80: Levels in Patients with Hematological Malignancies

The release of soluble forms of CD80 provides a potentially powerful mechanism for the modulation of anti-tumor responses. In this report we investigated whether a soluble form of CD80 (sCD80) circulates in vivo and whether levels are altered in patients with hematological malignancies. Circulating sCD80 was detected by ELISA in all normal donor (0.024-0.318 ng/ml) and patient (0.02-3.75 ng/ml) blood analyzed. The majority of acute myeloid leukemia (13/17) and multiple myeloma (11/12) patients had normal sCD80 levels. Significantly elevated levels were detected in chronic lymphocytic leukemia (CLL, P = 0.0001) and mantle cell lymphoma (MCL, P = 0.0002) patients. MCL patients had the highest levels with 8/9 having levels > 0.318 ng/ml. Increased sCD80 levels in CLL were significantly associated with poor prognosis markers such as low platelet (P = 0.01) and hemoglobin (P = 0.002) levels, elevated WBC counts (P = 0.03) and expression of CD38 (P = 0.048). The immunoreactivity of the sCD80 in both normal and patient plasma was inhibited by the presence of CTLA-4-Ig, suggesting sCD80 is functional. Comparison of sCD80 and soluble CD86 levels demonstrated that these molecules were independently elevated in 39% of patients. The finding that a proportion of CLL and the majority of MCL patients contain elevated levels of sCD80 and the demonstration that sCD80 can interact with CTLA-4-Ig suggests a potential role for sCD80 in modulating anti-tumor responses during the malignant process.

Endogenous thrombopoietin levels during the clinical management of acute myeloid leukaemia

Thrombocytopenia represents a major problem in the management of acute myeloid leukaemia (AML). The data regarding the alterations of endogenous thrombopoietin (TPO) regulation during the clinical course of AML are limited. The aim of this study was to investigate endogenous TPO dynamics in association with platelets during the clinical course of AML. We serially measured both TPO and platelets concurrently over the entire treatment period of newly diagnosed patients receiving both remission induction and consolidation chemotherapies. The median concentration of TPO in AML patients at the initial diagnosis was 469.71 pg/ml and increased significantly during the aplastic period due to remission induction chemotherapy (median: 1085.33 pg/ml) but then decreased to a level (median: 45.26 pg/ml) encountered in the healthy control subjects (median: 56.90 pg/ml). In the cytopenic period due to consolidation treatment, TPO level again increased significantly to a high level (median: 891.38 pg/ml) during the platelet nadir, but decreased toward normal (median: 100.75 pg/ml) after the thrombocytopenic period had elapsed. In conclusion, endogenous TPO levels exhibit an inverse fluctuation in relation to platelet counts during the clinical course of AML. Pharmacological stimulation of thrombopoiesis in AML with novel molecules, including the recombinant thrombopoietins and the small peptide agonists, should be based on a critical administration strategy that must consider the endogenous levels of TPO. TPO levels in distinct AML disease states may explain the unsuccessful recombinant TPO trials and could help to design better strategies for 'pharmacological stimulation of thrombopoiesis' in AML.

Detection of Single-strand Breaks and Base Damage in DNA of Blood Cells from Leukaemia Patients Receiving Chemo- and Radiotherapy

Chemotherapy combined with total-body irradiation (TBI), a conditioning regimen for bone-marrow transplantation (BMT), causes lesions in the cellular DNA of the patients treated. To understand possible consequences of the DNA damage induced during such treatment, information is required about the nature of the damage, the level of induction and its persistence, and about the importance of the various lesions for cell-lethality and/or mutation induction. Recently, we developed a sensitive immunochemical method to quantify single-strand breaks (SSB) in the DNA of mammalian cells. In addition, a modification of the so-called alkaline elution technique was introduced which allows quantification of SSB together with base damage (SSB+BD). These methods have now been applied successfully to study the in vivo induction and repair of DNA damage in WBC of leukaemia patients who prior to BMT were treated with cyclophosphamide (CY) and received TBI. SSB and SSB+BD were determined after two treatments with CY (60 mg kg-1) followed by TBI (4.5-8.6Gy). The CY treatments gave rise to rather persistent SSB. In addition to these, radiation-induced SSB and SSB+BD could be detected shortly after TBI. However, 105 min after TBI, these SSB could be observed no longer, as a result of rapid repair.

Plasma histamine and serum pepsinogen I concentrations in chronic myelogenous leukaemia

A male patient with multiple gastroduodenal ulcers and gastric hypersecretion due to hyperhistaminaemia associated with extreme basophilia occurring in chronic myelogenous leukaemia (CML) is described. In addition, plasma histamine levels and serum pepsinogen I concentrations, reflecting gastric acid secretion, were studied in 18 CML patients. As compared to controls, plasma histamine levels were clearly increased in CML patients and correlated well with the basophil count. Serum pepsinogen I concentrations were normal in 14 out of 17 cases and did not correlate with plasma histamine levels. This absence of a direct relation between plasma histamine concentrations and serum pepsinogen I levels suggests that a high concentration of circulating histamine does not inevitably lead to increased gastric acid secretion. This offers one explanation of the fact that, in spite of the frequent occurrence of basophilia and hyperhistaminaemia in CML, ulcerogenic diathesis is quite rare in this disease and complicates only cases with extreme basophilia.

Effect of granulocyte chalone on acute and chronic granulocytic leukaemia in man. Report of seven cases

This study reports results from the first clinical tests in which 7 patients with myeloid leukaemia (5 acute and 2 chronic leukaemias in metamorphosis) were treated from 4 to 45 days with granulocyte chalone, the tissue-specific endogenous inhibitor of granulopoiesis. It was observed that i.v. injection of partially purified chalone inhibits proliferation of leukaemic, and presumably also normal granulocytic cells, leaving all other cell types unaffected. Inhibition of leukaemic growth was distinct in 6 of the 7 patients; in 5 cases the inhibition was followed by acutal regression of the leukaemia, lasting up to several months in the absence of any maintenance therapy, and in one case the treatment led to a complete remission. Chalone treatment also resulted in an enhancement of erythropoiesis and megakaryopoiesis, and in phenomena some of which were totally unexpected, such as immunostimulation and a remarkable resistance to bacterial infections in the presence of extreme granulocytopenia. This study shows that granulocyte chalone is biologically active against myeloid leukaemia in man, but not that the therapeutic value of the impure chalone is superior to modern cytostatic drugs. Long-term therapeutic trials were not possible with the partially purified preparations available, mainly because of side-effects which prevented adequate dosing.

Historical perspective and clinical implications of the Pelger-Hüet cell

The unique historical aspects of Pelger and Huet's discovery of the Pelger-Huet cell highlight the diagnostic challenge that this morphologic finding presents to the physician. Making the diagnosis of the benign autosomal dominant anomaly is complicated by the morphologically similar pseudo-Pelger-Huet cell, which can signify underlying myeloid dsyplasia. This article relates the history of the Pelger-Huet anomaly as well as describes the clinical significance and diagnostic workup for the finding of a Pelger-Huet cell on peripheral smear.

Current and emerging strategies for the management of acute myeloid leukemia in the elderly

Acute myeloid leukemia (AML) accounts for approximately 80% of acute leukemias diagnosed in adults. The elderly are disproportionately affected by AML, as 35% of newly diagnosed patients are aged >or=75 and the median age at diagnosis is 67. Elderly individuals also respond less well to standard chemotherapy than do younger individuals, as reflected by lower complete remission and relapse-free survival rates in major clinical trials. A higher prevalence of comorbid conditions as well as the unique biological features of elderly AML patients account for the relatively poor response to therapy observed in this population. Compared with AML in younger individuals, for example, AML in the elderly more often emerges from a preceding myelodysplastic syndrome and is more frequently associated with poor-prognosis karyotypes such as 5q- or 7q-. The introduction of novel therapies over the past decade has already altered the treatment paradigm of elderly individuals with AML. The first of these to emerge was gemtuzumab ozogamicin. Other agents are currently under evaluation in clinical trials, including inhibitors of multidrug resistance, farnesyltransferase inhibitors, novel nucleoside analogues, and inhibitors of the FMS-like tyrosine kinase-3. This review describes the biological features of AML in the elderly and summarizes both the current and emerging strategies for the treatment of this disease in older individuals.

Spurious platelet counts in acute leukaemia with DIC due to cell fragmentation

Automated platelet counts in a patient with newly diagnosed AML M5 with extreme leukocytosis were reported as 129, 166 and 121 x 10(9)/1. Routine blood films showed a corresponding number of platelet-sized particles, judged to be platelets. The patient was treated for DIC with low-dose heparin infusion. Platelet transfusions were not given initially. The patient died 14 h after admission from intracerebral haematoma. The origin of the platelet-sized particles seen in routine stained blood films was examined by cytochemical and immunological staining for peroxidase, non-specific esterase, CD 13 and CD 33. About 1/3 of the fragments had the same staining characteristics as the leukaemia cells, indicating leukaemia cell origin. Staining for platelet-specific antigen GpIIIa was positive only in 4% of the platelet-sized fragments, with a calculated true platelet count of 4 x 10(9)/1. The presence of cell fragments masquerading as platelets should be suspected in leukaemia patients with bleeding symptoms and normal or near normal platelet counts.

Prognostic significance of myeloperoxidase expression in childhood acute myeloid leukemia

BACKGROUND

The percentage of myeloperoxidase (MPO)-positive blast cells is associated with prognosis in adult acute myeloid leukemia (AML), but this association is unsubstantiated in pediatric AML.

PROCEDURE

We retrospectively compared cytochemical MPO results with outcome in 154 patients younger than 21 years treated on three consecutive institutional protocols for newly diagnosed AML (1987-2001). Patients with FAB M0 and M7 AML (no MPO expression) or M3 AML (100% MPO expression) and Down's syndrome were excluded.

RESULTS

Median MPO expression was higher in FAB M2 subtype than in other subtypes (P < 0.0001) and differed significantly across cytogenetic risk groups (P = 0.002) with highest MPO expression among those with favorable karyotypes. The percentage of MPO-positive blasts was not significantly associated with the probability of complete remission (P = 0.97), event-free survival (P = 0.72), or survival (P = 0.76) in multivariate analyses that accounted for age, FAB subtype, presenting WBC count, cytogenetic and protocol treatment risk group. In analysis limited to patients with intermediate-risk cytogenetics, higher MPO expression appeared to be associated with improved EFS (P = 0.06) but was not associated with remission induction rate (P = 0.16) or overall survival (P = 0.38).

CONCLUSIONS

The percentage of MPO-positive blast cells is related to FAB subtype in pediatric AML but has limited prognostic relevance.

Prevalence of erythrocyte haemoglobin H inclusions in unselected patients with clonal myeloid disorders

Patients with clonal myeloid disorders, especially myelodysplastic syndromes (MDS), may acquire alpha-thalassaemia. To estimate the prevalence of this erythrocyte phenotype, we examined brilliant cresyl blue-stained blood smears from 201 patients with neoplastic myeloid disorders and 282 controls (195 non-clonal anaemia, 62 with medical illnesses without anaemia and 25 healthy persons). Haemoglobin H inclusions were detected in 8/100 patients with MDS (8%) and 2/81 (2.5%) patients with myeloproliferative disorders, but in none of the acute leukaemia patients or controls. We conclude that the emergence of thalassaemic clones may be relatively common in the disordered marrow milieu of MDS.