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Non-homologous end joining (NHEJ) is an important determinant of genomic stability in mammalian cells. This DNA repair pathway is upregulated in a subset of B-cell chronic lymphocytic leukaemia (B-CLL) cells resistant to DNA damage-induced apoptosis. Using an in vitro assay for double-strand breaks (DSB) end ligation, we studied the fidelity of DSB repair in B-CLL cells which were resistant or sensitive to in vitro DSB-induced apoptosis with concomitant patients’ resistance or sensitivity to chemotherapy, respectively. The fidelity of DNA repair was determined by DNA sequencing of polymerase chain reaction products cloned in pGEM-T vector. Sequence analysis of DNA end junctions showed that the frequency of accurate ligation was higher in sensitive B-CLL cells and control cell lines, than in resistant cells where end joining was associated with extended deletions. Upregulated and error-prone NHEJ in resistant cells could be a quite possible mechanism underlying both genomic instability and poor clinical outcome. [ABSTRACT FROM AUTHOR]

Primary intraocular lymphoma (PIOL) is a rare presentation of lymphoma that is particularly difficult to recognize. In our institution, 36 cases of PIOL were diagnosed between March 1997 and July 2002. The recognition of lymphoma cells by cytology with or without immunophenotyping on slides generated a strong suspicion of the diagnosis in 34 of 36 cases. The diagnosis was confirmed by measurement of interleukin-10 (IL-10) in the vitreous humour or aqueous humour; high levels were observed in 35 of 36 cases, all were of B-cell origin. As expected, the only case with T-cell lymphoma had a very low level of IL-10. Furthermore, IL-10 levels excluded this diagnosis in two cases that were incorrectly suspected of PIOL after cytological examination. Finally, detection of clonality by polymerase chain reaction techniques, performed in 29 cases, represented a helpful tool in diagnosing PIOL as this approach definitively confirmed the diagnosis of B- or T-cell lymphoma in 17 cases. [ABSTRACT FROM AUTHOR]

Ubiquitin-proteasome-dependent protein processing appears to be an essential component in the control of radiation-induced apoptosis in human lymphocytes. This control is altered in chronic lymphocytic leukaemia (CLL), compared to that of normal human lymphocytes which mainly showed high apoptotic values after irradiation, but in some cases no sensitivity was observed. Interestingly, lactacystin activated the apoptotic pathway in both radio-resistant and sensitive CLL cells, at doses which had no effect in normal cells where significantly higher concentrations were required. Therefore the resistance of some CLL cells to apoptosis initiation by radiation does not correlate to observed increased sensitivity to lactacystin. The nuclear level of the transcription factor NF-κB or the cytoplasmic level of IκBα remained unaltered upon irradiation or lactacystin CLL cells treatment, suggesting that the activity of the other factors involved in apoptotic death control were altered through proteasomal inhibition. These results strongly suggest an essential role of the ubiquitin system in apoptotic cell death control in CLL lymphocytes. The inhibition of proteasome-ubiquitin-dependent processing could be a discriminatory apoptotic stimulus between normal versus malignant lymphocytes and therefore might potentially be of use in this specific human pathology. [ABSTRACT FROM AUTHOR]

Objectives This study investigates whether achieving complete remission ( CR) with undetectable minimal residual disease ( MRD) after allogeneic stem cell transplantation (allo- SCT) for chronic lymphocytic leukemia ( CLL) affects outcome. Methods We retrospectively studied 46 patients transplanted for CLL and evaluated for post-transplant MRD by flow cytometry. Results At transplant time, 43% of the patients were in CR, including one with undetectable MRD, 46% were in partial response, and 11% had refractory disease. After transplant, 61% of the patients achieved CR with undetectable MRD status. By multivariate analysis, reaching CR with undetectable MRD 12 months after transplant was the only factor associated with better progression-free survival ( P = 0.02) and attaining undetectable MRD, independently of the time of negativity, was the only factor that correlated with better overall survival ( P = 0.04). Conclusion Thus, achieving undetectable MRD status after allo- SCT for CLL is a major goal to improve post-transplant outcome. [ABSTRACT FROM AUTHOR]

Introduction We aimed to confirm the diagnostic value and to evaluate the pre- and post-therapeutic prognostic value of cerebrospinal fluid (CSF) concentrations of interleukin (IL)-10 and IL-6 in patients with diffuse large B-cell primary central nervous system lymphoma (PCNSL). Patients and methods IL-10 and IL-6 concentrations were measured in 79 patients with PCNSL at diagnosis and in 40 control individuals. Fifty-four PCNSL patients underwent repeat assessments starting at diagnosis. Results The IL-10 concentration distinguished PCNSL from other neurologic diseases with a sensitivity of 88.6% and a specificity of 88.9% with a cutoff of 4 pg/ml. In a multivariate analysis of PCNSL patients, CSF involvement was associated with a higher IL-10 concentration (mean log (IL-10) of 4.4 versus 2.5 pg/ml, respectively, p = 0.0004). The pre-therapeutic IL-10 concentration had no prognostic impact on outcome. The IL-10 concentration decreased after treatment for most patients tested. Among patients with complete remission or partial remission, as evaluated by magnetic resonance imaging (MRI), a persistent detectable IL-10 level in the CSF at the end of treatment was associated with a negative impact on progression-free survival (PFS) (1-year PFS: 15%, 95% confidence interval [CI]: 2.5–38% versus 59%, 95% CI: 32–78%, respectively, p = 0.0004). Conclusion Our study confirmed that IL-10 is a useful biomarker for the diagnosis of PCNSL. We highlight new findings showing that the IL-10 level in the CSF could be used as a surrogate marker for CSF involvement and that the post-treatment IL-10 concentration could complement standard MRI for therapeutic response assessment in PCNSL. [ABSTRACT FROM AUTHOR]

Although TP53, NOTCH1, and SF3B1 mutations may impair prognosis of patients with chronic lymphocytic leukemia (CLL) receiving frontline therapy, the impact of these mutations or any other, alone or in combination, remains unclear at relapse. The genome of 114 relapsed/refractory patients included in prospective trials was screened using targeted next-generation sequencing of the TP53, SF3B1, ATM, NOTCH1, XPO1, SAMHD1, MED12, BIRC3, and MYD88 genes. We performed clustering according to both number and combinations of recurrentgene mutations. The number of genes affected by mutation was ≥2, 1, and 0 in 43 (38%), 49 (43%), and 22 (19%) respectively. Recurrent combinations of ≥2 mutations of TP53, SF3B1, and ATM were found in 22 (19%) patients. This multiple-hit profile was associated with a median progression-free survival of 12 months compared with 22.5 months in the remaining patients (P 5 .003). Concurrent gene mutations are frequent in patients with relapsed/refractory CLL and are associated with worse outcome. [ABSTRACT FROM AUTHOR]

Background: Chronic lymphocytic leukemia (CLL), the most common adulthood leukemia, is characterized by the accumulation of abnormal CD5+ B lymphocytes, which results in a progressive failure of the immune system. Despite intense research efforts, drug resistance remains a major cause of treatment failure in CLL, particularly in patients with dysfunctional TP53. The objective of our work was to identify potential approaches that might overcome CLL drug refractoriness by examining the pro-apoptotic potential of targeting the cell surface receptor CD47 with serum-stable agonist peptides. Methods and Findings: In peripheral blood samples collected from 80 patients with CLL with positive and adverse prognostic features, we performed in vitro genetic and molecular analyses that demonstrate that the targeting of CD47 with peptides derived from the C-terminal domain of thrombospondin-1 efficiently kills the malignant CLL B cells, including those from high-risk individuals with a dysfunctional TP53 gene, while sparing the normal T and B lymphocytes from the CLL patients. Further studies reveal that the differential response of normal B lymphocytes, collected from 20 healthy donors, and leukemic B cells to CD47 peptide targeting results from the sustained activation in CLL B cells of phospholipase C gamma-1 (PLCγ1), a protein that is significantly over-expressed in CLL. Once phosphorylated at tyrosine 783, PLCγ1 enables a Ca2+-mediated, caspase-independent programmed cell death (PCD) pathway that is not down-modulated by the lymphocyte microenvironment. Accordingly, down-regulation of PLCγ1 or pharmacological inhibition of PLCγ1 phosphorylation abolishes CD47-mediated killing. Additionally, in a CLL-xenograft model developed in NOD/scid gamma mice, we demonstrate that the injection of CD47 agonist peptides reduces tumor burden without inducing anemia or toxicity in blood, liver, or kidney. The limitations of our study are mainly linked to the affinity of the peptides targeting CD47, which might be improved to reach the standard requirements in drug development, and the lack of a CLL animal model that fully mimics the human disease. Conclusions: Our work provides substantial progress in (i) the development of serum-stable CD47 agonist peptides that are highly effective at inducing PCD in CLL, (ii) the understanding of the molecular events regulating a novel PCD pathway that overcomes CLL apoptotic avoidance, (iii) the identification of PLCγ1 as an over-expressed protein in CLL B cells, and (iv) the description of a novel peptide-based strategy against CLL. [ABSTRACT FROM AUTHOR]

The article presents a study on the use of RNA-based assays in assessing TP53, a regulator of the DNA-damage response pathway, functionality in patients with chronic lymphocytic leukemia (CLL). It discusses the aims of the study, the characterization of CLL, and mutational analysis of TP53 and ATM regulators.

In systemic mastocytosis (SM), clinical problems arise from factor-independent proliferation of mast cells (MCs) and the increased release of mediators by MCs, but no human cell line model for studying NIC activation in the context of SM is available. We have created a stable stem cell factor (SCF) -dependent human MC line, ROSAKIT WT, expressing a fully functional immunoglobulin E (IgE) receptor. Transfection with KIT D816V converted ROSAKIT WT cells into an SCF-independent clone, ROSAKIT D816V, which produced a mastocytosis-like disease in NSG mice. Although several signaling pathways were activated, ROSAKIT D816V did not exhibit an increased, but did exhibit a decreased responsiveness to IgE-dependent stimuli. Moreover, NSG mice bearing ROSAKIT D816V-derived tumors did not show mediator-related symptoms, and KIT D816V-positive MCs obtained from patients with SM did not show increased IgE-dependent histamine release or CD63 upregulation. Our data show that KIT D816V is a disease-propagating oncoprotein, but it does not activate MCs to release proinflammatory mediators, which may explain why mediator-related symptoms in SM occur preferentially in the context of a coexisting allergy. ROSAKIT D816V may provide a valuable tool for studying the pathogenesis of mastocytosis and should facilitate the development of novel drugs for treating SM patients. [ABSTRACT FROM AUTHOR]

The ATM-p53 DNA damage response pathway plays a crucial role in chemoresistance in chronic lymphocytic leukemia, as indicated by the adverse prognostic impact of deletions of 17p (locus of TP53) and 11q (locus of ATM) detected by fluorescence in situ hybridization (FISH) analysis. In addition to deletions, mutations in these respective genes are also associated with chemoresistance, and add to the prognostic information provided by FISH. In order to explore the possibility that dysfunction of the ATM-p53 pathway might also result from mechanisms other than ATM/ TP53 deletion/mutation, assays have been developed that probe the functional integrity of the ATM-p53 pathway. Currently, four different p53 function assays have been developed that are based on the measurement of p53 and p53-dependent genes at the RNA (real-time polymerase chain reaction [RT-PCR] p21; RT-PCR miR34a; reverse transcription-multiplex ligation-dependent probe amplification assay [RT-MLPA] p21, bax, puma and CD95) or protein (fluorescence activated cell sorting [FACS]p53-p21) level in untreated cells or following irradiation or drug treatment. Here we provide an overview of these assays based on the available literature. [ABSTRACT FROM AUTHOR]

Primary intraocular lymphoma (PIOL), also called primary vitreoretinal lymphomas, often masquerades as uveitis. This misdiagnosis can result in subsequent brain involvement and oculocerebral lymphoma (OCL). In this study, we sought to characterize the helper T-cell type 1 (Th1)/Th2 cytokine profile in vitreous samples from patients with PIOL, OCL, uveitis and controls with non-inflammatory disease. Vitreous and aqueous humor samples from 87 patients with PIOL (n = 30), OCL (n = 12), uveitis (n = 34), and retinal detachment (RD) without hemorrhage (n = 11) were analyzed and their concentrations of interleukin (IL)-2, IL-4, IL-6, IL-10, interferon (IFN)-γ, and tumor necrosis factor (TNF)-α were determined by flow cytometric bead arrays (CBA). The IL-10 levels determined by CBA were compared with those by ELISA. IL-10 concentrations measured by CBA and ELISA were highly correlated. IL-2, IL-4, and TNFα were not detected in any sample. The only cytokine detected at a significant level in samples from RD vitreous was IL-6. The IL-10/IL-6 ratio, as previously reported, was slightly higher in PIOL than in uveitis samples, but not for all patients. Cytokine profiles from PIOL and OCL samples did not differ. The combination of the IL-10/IL-6 and IL-10/IFNγ ratios was highly informative for discriminating PIOL/OCL from uveitis samples and for therapeutic follow up of PIOL. This strategy might be very helpful as an initial screening to rule out PIOL in patients thought to have uveitis. [ABSTRACT FROM AUTHOR]

Purpose: To determine the presence of clinicopathological correlations for primary intraocular non-Hodgkin lymphoma (NHL)in fluorescein angiographies (FA), indocyanine green (ICGA) angiographies, and optical coherence tomography (OCT) images. Design: Comparative retrospective interventional case series. Methods: Institutional practice. All serial patients who underwent vitreous sampling for cytological analysis over a 70-month period were reviewed. Clinical, angiographic, and tomographic findings present prior to tissue diagnosis were re-evaluated in a masked fashion. Results: Cytological analysis of 256 vitreous specimens from 244 patients was performed. The final diagnoses were infections in 42 cases (17.2%) and immune-mediated diseases in 34 cases (13.9%). In 59 cases (24.2%), neoplastic disease was present, and 53 (21.7%) of these were primary intraocular NHL. OCT images showed nodular hyperreflective lesions in the retinal pigment epithelium (RPE) of both intraocular NHL and nonintraocular NHL patients. Clusters of numerous hypofluorescent small lesions revealed by FA that corresponded to punctate whitish lesions in the fundus and rare round clustered hypofluorescent lesions revealed by ICGA were associated with intraocular NHL diagnosis. The positive predictive value was 88.9% and the negative predictive value was 85%. The odds ratio risk was 45.22. Conclusion: The presence of clusters of round stable hypofluorescent lesions in FA that are scarce in ICGA, with corresponding RPE hyperreflective nodular lesions on OCT, warrants obtaining biopsies for cytology, immunostaining, and molecular biology exams. [Copyright &y& Elsevier]

Abstract: Tachykinins are a family of structurally related peptides, including substance P (SP), hemokinin-1 (HK-1), neurokinin A (NKA), and neurokinin B. SP and NKA have been shown to modulate hematopoiesis and rat/mouse HK-1 has been found to be involved in the survival and differentiation of mouse B-cells. This study was designed to assess the expression of tachykinins with a focus on human HK-1 (hHK-1) in human B lymphocytes and the role of these peptides in cell differentiation, apoptosis and proliferation. Expression of tachykinin and tachykinin receptor mRNA was determined quantitatively in human B lymphoproliferative malignancies and compared to normal B-cells. Expression of hHK-1 and NK1 receptor, but not SP, was detected in human B-lymphocytes, and was up-regulated in B-lymphocytes from chronic lymphocytic leukemia and non-Hodgkin''s lymphoma, while it was down-regulated in acute lymphoblastic leukemia. Moreover, hHK-1, in contrast to SP, was able to induce proliferation of human pre-B lymphocytes through a NK1 receptor-independent mechanism. These data suggest a role for hHK-1 in normal and pathological B lymphopoiesis, and open the door to a better understanding of the physiopathological mechanisms leading to lymphoproliferative malignancies. [Copyright &y& Elsevier]

Abstract: Using array-based CGH, we identified 2p gain in 22/78 (28%) untreated Binet stages B/C CLL, which was the second most frequent copy number change after 13q deletion. It never occurred as a sole abnormality and was associated with other changes (6q deletion; 1p gain). The region of 2p gain frequently included two oncogenes, REL and MYCN. All patients with gain of REL were unmutated for IGHV (p =0.03). Gain of MYCN was associated with increased mRNA expression (p =0.005), suggesting a pathogenic role for MYCN. Gain of 2p appears to be a marker of progression and may contribute to the poor prognosis. [Copyright &y& Elsevier]

Several prognostic factors can predict the rapid progression in chronic lymphocytic leukaemia (CLL), including IGHV mutational status, cytogenetic abnormalities and, more recently, LPL/ ADAM29 expression. In contrast, few studies have been devoted to the influence of these factors on clinical outcome in responding patients after therapy. We here propose to analyse the impact of IGHV gene status, LPL and ADAM29 gene expression on disease-free survival (DFS) and overall survival (OS) in 41 stage B or C CLL patients in remission after oral fludarabine plus cyclophosphamide. The median follow-up was of 64 (16–74) months. Sequencing of IGHV showed mutated (M) VH genes in 16 of 41 cases and unmutated (UM) in 25 cases. Analysis of LPL and ADAM29 expression in 35 of 41 cases showed overexpression of ADAM29 in 17 cases (14 M and three UM) and LPL in 18 cases (all UM). Patients expressing UM IGHV and LPL had shorter DFS and OS when compared to patients expressing M IGHV and/or ADAM29. Furthermore, blood minimal residual disease (MRD) evaluation using four-colour flow cytometry was performed in 33 out the 41 patients. We showed that patients who achieved phenotypic remission displayed longer DFS than those with MRD+. Our results support the use of LPL and ADAM29 gene expression associated to IGHV mutational status for predicting the clinical outcome of patients treated by oral fludarabine + cyclophosphamide and could be considered for treatment strategies. [ABSTRACT FROM AUTHOR]

Patients with chronic lymphocytic leukaemia (CLL) treated with a combination of fludarabine, cyclophosphamide and rituximab show a high response rate. However, only a poor response is observed following rituximab monotherapy. The use of chemo-immunotherapy is often associated with haematological and infectious complications. Thus, an antibody with an enhanced ability to kill CLL cells could lead to better clinical responses to antibody monotherapy and the possibility of lowering drug doses during chemo-immunotherapy. We generated a chimeric anti-CD20 monoclonal antibody (mAb), EMAB-6, which has a low fucose content. Apoptosis and complement activities for EMAB-6 were similar to those seen for rituximab. By contrast, EMAB-6 mAb showed improved Fcγ receptor IIIA (FcγRIIIA)/CD16 binding and FcγRIIIA-dependent effector functions. It induced a higher in vitro antibody-dependent cellular cytotoxicity against CLL cells and a higher FcγRIIIA-mediated interleukin-2 production by FcγRIIIA+ Jurkat cells in the presence of CLL cells at both low and maximally saturating concentrations. Comparative studies between CLL and lymphoma cells coated with EMAB-6 or rituximab indicated that the difference of efficacy was more pronounced at low doses and when target cells expressed fewer CD20 molecules. Thus, EMAB-6 mAb represents a promising drug candidate for the treatment of CLL by inducing a strong cytotoxicity against tumour cells that express low CD20 levels. [ABSTRACT FROM AUTHOR]

B-chronic lymphocytic leukemia (B-CLL) is characterized by a highly variable clinical course which has long remained a stumbling block for clinicians. This variability appears to arise from complex molecular alterations identified in malignant cells from patient subsets. Recent studies have focused in particular on identifying new molecular markers to help predict the most effective and adapted treatments. In addition to the mutation status of immunoglobulin variable heavy-chain region (IgV H ) genes, which is a well-established predictive factor in B-CLL, these new markers include defects of cell factors involved in the maintenance of genome stability, such as telomere function, DNA repair, ATM and p53. Other predictive factors, such as tyrosine kinase Zap-70 and soluble factors found in patient sera, may be associated with B-cell receptor signal transduction. Interestingly, an alteration of these factors fits closely, though not strikingly, with the absence of somatic mutations in IgV H genes, suggesting that the latter may be due either to epigenetic events leading to an unstable genome or to an inherited defect in the immune response of malignant B-cells. Recent lessons from Zap-70 expression/phosphorylation suggest that some of these markers may reflect the defective pathways in B-CLL cells rather than being markers of cell malignancy per se . Furthermore, specific subsets of markers are found in patient cells resistant to treatment. Current studies on gene expression profiling and proteomic analyses should soon lead to a better understanding of how these pathways are affected, especially in multi-drug resistant B-CLL. [ABSTRACT FROM AUTHOR]

Abstract: Burkitt-type acute leukemia cells were present in the bone marrow of a patient with B-prolymphocytic leukemia diagnosed from peripheral blood cell morphology. Immunophenotype analysis confirmed morphological patterns. Cytogenetic and fluorescence in situ hybridization (FISH) analysis showed an identical t(8;22)(q24;q21) with MYC locus rearrangement in blood and bone marrow cells, with additional chromosome abnormalities in the bone marrow. In addition, the loss of one copy of the TP53 gene and identical IGH DNA clonal rearrangements were shown with FISH and polymerase chain reaction analysis respectively in the two types of leukemic cells. These data indicated the common origin of the two coexisting leukemias and are the first example of such occurrence in a leukemic patient. [Copyright &y& Elsevier]

Abstract: A case of de novo acute myeloblastic leukemia (AML) M2, with trisomy 4 and double minute (dmin) chromosomes is reported. Amplification of the MYC gene ascertained by FISH was associated with dmin. A review of the literature of trisomy 4-dmin-associated AML shows that this entity preferentially occurs in elderly women and is not always associated with previously identified exposition to mutagens. [Copyright &y& Elsevier]

Ligation of CD47 by its natural ligand thrombospondin (TSP), or cross-linking by CD47 antibodies, triggers caspase-independent cell death in normal and leukemic cells. This kind of cell death is characterised by the cytoplasmic events of apoptosis including externalisation of phosphatidylserines and mitochondria swelling. We report herein selective mitochondrial changes in CD47–dependent cell death of T cells. After T cell stimulation via CD47, a rapid mitochondrial transmembrane potential (ΔΨm) disruption is accompanied by the production of reactive oxygen species (ROS) and phosphatidylserine exposure. Surprisingly, mitochondrial dysfunction does not induce cytochrome c or AIF release. Moreover, the dying cells do not exhibit caspase-3 activation and display intact nuclei without any large-scale, or oligonucleosomal DNA fragmentation. We conclude that ΔΨm loss and ROS production are an early step in CD47–dependent killing and neither cytochrome c, nor AIF are implicated in this new cell death pathway. [Copyright &y& Elsevier]

Human cancer is characterised by complex molecular aberrations which result in a wide variety of clinical manifestations. B-cell chronic lymphocytic leukaemia (B-CLL) is particularly diverse, both in terms of molecular changes and clinical course, and consequently our understanding of the pathology of this disease is generally poor. Furthermore, the heterogeneity of this tumour type coupled with the absence of an obvious genetic "hallmark", such as gain of oncogene function or loss of suppressor-gene function, has led many investigators to question whether B-CLL is a single disease entity. In most cases, B-CLL does not show specific reciprocal chromosomal translocations as found in other haemopoietic malignant diseases. The genomic instability of B-CLL results in numerous different types of chromosomal losses and gains, giving rise to unsettled karyotypes among individuals with this disease. Nevertheless, genetic data imply that B-CLL is a single disease characterised by a common gene-expression profile and by the existence of specific subtypes that may have clinical correlates in patients. [ABSTRACT FROM AUTHOR]

Human cancer is characterised by complex molecular aberrations which result in a wide variety of clinical manifestations. B-cell chronic lymphocytic leukaemia (B-CLL) is particularly diverse, both in terms of molecular changes and clinical course, and consequently our understanding of the pathology of this disease is generally poor. Furthermore, the heterogeneity of this tumour type coupled with the absence of an obvious genetic “hallmark”, such as gain of oncogene function or loss of supressor-gene function, has led many investigators to question whether B-CLL is a single disease entity. In most cases, B-CLL does not show specific reciprocal chromosomal translocations as found in other haemopoietic malignant diseases. The genomic instability of B-CLL results in numerous different types of chromosomal losses and gains, giving rise to unsettled karyotypes among individuals with this disease. Nevertheless, genetic data imply that B-CLL is a single disease characterised by a common gene-expression profile and by the existence of specific subtypes that may have clinical correlates in patients. [Copyright &y& Elsevier]

Summary. We describe a new flow-cytometric analysis using quadruple labelling with anti-CD19, CD20, CD5, CD79b monoclonal antibodies and sequential gating. We determined a novel criteria defined by BCD5+ CD79b–/low /total BCD5+ cells ratio (BCD5+ R), and compared it with the previous definition of phenotypic remission, based on CD19+ CD5+ coexpression, and with complementarity-determining region 3 polymerase chain reaction (CDR3 PCR) and clonotypic PCR (cPCR). A series of 54 peripheral blood samples from 21 chronic lymphocytic leukaemia (CLL) patients in complete haematological remission and a series of 16 from normal volunteers were analysed. In normal controls, the BCD5+ R was always < 0·2. The sensitivity of the BCD5+ R was 1 × 10-4 vs 5 × 10-2 for CDR3 PCR and 1 × 10-5 for cPCR. Among the 54 CLL samples, 35 had a BCD5+ R < 0·2 and showed polyclonal CDR3 PCR, whereas the cPCR was positive in 12 out of 20 tested. In the remaining 19 samples, BCD5+ R was > 0·2, CDR3 PCR was monoclonal in 16 out of 19 and cPCR positive in 14 out 14 tested, including one out of three samples with polyclonal CDR3 amplification. Even though cPCR remains the most sensitive method to evaluate MRD, this new, sensitive and specific flow cytometric parameter, the BCD5+ R, is more suitable than CDR3 PCR for routine clinical MRD assessment in CLL. [ABSTRACT FROM AUTHOR]

Two patients with Ph-positive chronic myelocytic leukemia in erythroblastic transformation and rearrangement of the short arm of chromosome 18 are reported. Fluorescence in situ hybridization studies showed that the 18p rearrangement resulted from translocation of the main part of chromosome 22 long arm to 18p, including BCR-ABL1 fusion. The 18p abnormality resulted, thus, in loss of 18p and duplication of BCR-ABL1 in both patients. The possible relation to the erythroblastic type of blastic phase is briefly discussed. In addition an apparently intact germline ABL1 gene was duplicated and inserted into chromosome 6 at band p21 in one of these patients. [Copyright &y& Elsevier]

Ligation of CD47 triggers caspase-independent programmed cell death (PCD) in normal and leukemic cells. Here, we characterize the morphological and biochemical features of this type of death and show that it displays the hallmarks of type III PCD. A molecular and biochemical approach has led us to identify a key mediator of this type of death, dynamin-related protein 1 (Drp1). CD47 ligation induces Drp1 translocation from cytosol to mitochondria, a process controlled by chymotrypsin-like serine proteases. Once in mitochondria, Drp1 provokes an impairment of the mitochondrial electron transport chain, which results in dissipation of mitochondrial transmembrane potential, reactive oxygen species generation, and a drop in ATP levels. Surprisingly, neither the activation of the most representative proapoptotic members of the Bcl-2 family, such as Bax or Bak, nor the release of apoptogenic proteins AIF (apoptosis-inducing factor), cytochrome c, endonuclease G (EndoG), Omi/HtrA2, or Smac/DIABLO from mitochondria to cytosol is observed. Responsiveness of cells to CD47 ligation increases following Drp1 overexpression, while Drp1 downregulation confers resistance to CD47-mediated death. Importantly, in B-cell chronic lymphocytic leukemia cells, mRNA levels of Drp1 strongly correlate with death sensitivity. Thus, this previously unknown mechanism controlling caspase-independent type III PCD may provide the basis for novel therapeutic approaches to overcome apoptotic avoidance in malignant cells. [ABSTRACT FROM AUTHOR]