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AimsDetermination of the number of plasma cells in bone marrow biopsies is required for the diagnosis and ongoing evaluation of plasma cell neoplasms. We developed an automated digital enumeration platform to assess plasma cells identified by antigen expression in whole bone marrow sections in multiple myeloma, and compared it with manual assessments.MethodsBone marrow trephine biopsy specimens from 91 patients with multiple myeloma at diagnosis, remission and relapse were stained for CD138 and multiple myeloma oncogene 1 (MUM1). Manual assessment and digital quantification were performed for plasma cells in the entire trephine section. Concordance rates between manual and digital methods were evaluated for each antigen by intraclass correlation analyses (ICC) with associated Spearman’s correlations.ResultsThe digital platform counted 16 484–1 118 868 cells and the per cent CD138 and MUM1-positive plasma cells ranged from 0.05% to 93.5%. Overall concordance between digital and manual methods was 0.63 for CD138 and 0.89 for MUM1. Concordance was highest with diffuse plasma cell infiltrates (MUM1: ICC=0.90) and lowest when in microaggregates (CD138: ICC=0.13). Manual counts exceeded digital quantifications for both antigens (CD138: mean=26.4%; MUM1: mean=9.7%). Diagnostic or relapse threshold counts, as determined by CD138 manual assessments, were not reached with digital counting for 16 cases (18%).ConclusionsAutomated digital enumeration of the entire, immunohistochemically stained bone marrow biopsy section can accurately determine plasma cell burden, irrespective of pattern and extent of disease (as low as 0.05%). This increases precision over manual visual assessments which tend to overestimate plasma burden, especially for CD138, and when plasma cells are in clusters.

No specific translocation is associated with myeloproliferative neoplasms (MPNs). However, an interstitial deletion involving subband 17q11.2 which includes the NF1 gene, although rare, is a recurrent aberration in several myeloid disorders including MPNs. For the first time, we report an acquired novel translocation involving 10p13 and 17q11.2 in a 62-year-old Caucasian female which was referred for investigation of chronic and persistent unexplained thrombocytosis. The patient had no history of hematological sequelae and genomic testing for JAK2, CALR, and MPL mutations were negative. She was subsequently diagnosed with a triple negative essential thrombocythemia. Array-CGH analysis noted that the translocation harbored two cryptic deletions, one of which involved 17q11.2 encompassing the NF1 gene. One of the junction breakpoints involved the SUZ12 gene. Immunohistochemical assessment of the marrow trephine showed increased megakaryocytic expression of the SUZ12 protein, as well as EZH2 and Ki67; biochemical abnormalities suggestive of excess megakaryocytic hyperplasia. This novel translocation may affect the expression of SUZ12 and its downstream targets, and may represent a unique pathogenomic etiology which drives chronic thrombocytosis in essential thrombocythemia.

Simple Summary Approximately 50% of patients with uveal melanoma will develop incurable metastatic disease. This can be predicted, but requires a biopsy of the eye, which outside of centres of excellence, are not routinely performed. Given that uveal melanoma spreads through the blood, utilising circulating tumour cells from the blood might provide an alternative minimally invasive method to avoid the biopsy. However, the clinical application hinges on the detection rate of circulating tumour cells. Herein we assessed markers to improve the capture and detection of uveal melanoma circulating tumour cells and found that they could be detected in 86% of patients. We further found that ≥3 circulating tumour cells was significantly associated with worse survival. Abstract (1) Background: The stratification of uveal melanoma (UM) patients into prognostic groups is critical for patient management and for directing patients towards clinical trials. Current classification is based on clinicopathological and molecular features of the tumour. Analysis of circulating tumour cells (CTCs) has been proposed as a tool to avoid invasive biopsy of the primary tumour. However, the clinical utility of such liquid biopsy depends on the detection rate of CTCs. (2) Methods: The expression of melanoma, melanocyte, and stem cell markers was tested in a primary tissue microarray (TMA) and UM cell lines. Markers found to be highly expressed in primary UM were used to either immunomagnetically isolate or immunostain UM CTCs prior to treatment of the primary lesion. (3) Results: TMA and cell lines had heterogeneous expression of common melanoma, melanocyte, and stem cell markers. A multi-marker panel of immunomagnetic beads enabled isolation of CTCs in 37/43 (86%) patients with UM. Detection of three or more CTCs using the multi-marker panel, but not MCSP alone, was a significant predictor of shorter progression free (p = 0.040) and overall (p = 0.022) survival. (4) Conclusions: The multi-marker immunomagnetic isolation protocol enabled the detection of CTCs in most primary UM patients. Overall, our results suggest that a multi-marker approach could be a powerful tool for CTC separation for non-invasive prognostication of UM.

Background Acute myeloid leukaemia (AML) results from the clonal expansion of blast cells of myeloid origin driven by genomic defects. The advances in next-generation sequencing (NGS) have allowed the identification of many mutated genes important in the pathogenesis of AML. Aims In this study, we aimed to assess the mutation types and frequency in a Chinese cohort presenting with de novo AML cohort using a targeted NGS strategy. Methods In total, we studied samples from 87 adult patients with de novo AML who had no prior history of cytotoxic chemotherapy. Samples were evaluated using a 120-gene targeted NGS panel to assess the mutation profile. Results Of the 87 AML patients, there were 60 (69%) with a normal karyotype. 89.7% of patients had variants, with an average of 1.9 mutations per patient (range: 0-5 mutations per patient). DNMT3A variants were the most common, being detected in 33 patients (37.9%). NPM1 (34.5%), IDH1/2 (24.1%) and FLT3-ITD (20.7%) mutations was the next most common. Of the patients with DNMT3A mutations, 24.2% also had mutations NPM1 and FLT3-ITD and 6.1% NPM1, FLT3-ITD and IDH mutations. Conclusion Both DNMT3A and NPM1 mutations were more common than in other Chinese and Western AML cohorts that have been studied. DNMT3A mutations tended to co-occur with NPM1 and FLT3-ITD mutations and were most commonly seen with a normal karyotype.

Imaging flow cytometry is an automated method that enables cells and fluorescent signals to be visualized and quantified. Here, we describe a new imaging flow cytometry method whereby fluorescence in situ hybridization (FISH) is integrated with cell phenotyping. The method, called "immuno-flowFISH," provides an exciting new dimension for the analysis of genomic changes in cytological samples (e.g., blood, bone marrow). Cells are analyzed in suspension without any requirement for prior cell isolation or separation. Multiple antibodies and FISH probes, each with a unique fluorophore, can be added and many thousands of cells analyzed. Specific cell populations are identified by their antigenic profile and then analyzed for the presence of chromosomal defects. Immuno-flowFISH was applied to the assessment of chronic lymphocytic leukemia (CLL), a mature B-cell neoplasm where chromosomal abnormalities predict prognosis and treatment requirements. This integrated immunophenotyping and multi-probe FISH strategy could detect both structural and numerical chromosomal changes involving chromosomes 12 and 17 in CLL cells. Given that many thousands of cells were analyzed and the leukemic cells were positively identified by their immunophenotype, this multi-probe method adds precision to the cytogenomic analysis of CLL. © 2021 Wiley Periodicals LLC.

Myeloproliferative neoplasms are characterised by somatic mutations in pathways that regulate cell proliferation, epigenetic modifications, RNA splicing or DNA repair. Assessment of the mutational profile assists diagnosis and classification, but also aids assessment of prognosis, and may guide the use of emerging targeted therapies. The most practical way to provide information on numerous genetic variants is by using massively parallel sequencing, commonly in the form of disease specific next generation sequencing (NGS) panels. This review summarises the diagnostic and prognostic value of somatic mutation testing in Philadelphia-negative myeloproliferative neoplasms: polycythaemia vera, essential thrombocythaemia, primary myelofibrosis, chronic neutrophilic leukaemia, systemic mastocytosis, and chronic eosinophilic leukaemia. NGS panel testing is increasing in routine practice and promises to improve the accuracy and efficiency of pathological diagnosis and prognosis. Refereed/Peer-reviewed

Gray platelet syndrome (GPS) is a rare recessive disorder caused by variants in NBEAL2 and characterized by bleeding symptoms, the absence of platelet ɑ-granules, splenomegaly and bone marrow (BM) fibrosis. Due to its rarity, it has been difficult to fully understand the pathogenic processes that lead to these clinical sequelae. To discern the spectrum of pathological features, we performed a detailed clinical genotypic and phenotypic study of 47 GPS patients. We identified 33 new causal variants in NBEAL2. Our GPS patient cohort exhibited known phenotypes, including macro-thrombocytopenia, BM fibrosis, megakaryocyte emperipolesis of neutrophils, splenomegaly, and elevated serum vitamin B12 levels. We also observed novel clinical phenotypes; these include reduced leukocyte counts and increased presence of autoimmune disease and positive autoantibodies. There were widespread differences in the transcriptome and proteome of GPS platelets, neutrophils, monocytes, and CD4-lymphocytes. Proteins less abundant in these cells were enriched for constituents of granules, supporting a role for Nbeal2 in the function of these organelles across a wide range of blood cells. Proteomic analysis of GPS plasma showed increased levels of proteins associated with inflammation and immune response. One quarter of plasma proteins increased in GPS are known to be synthesized outside of hematopoietic cells, predominantly in the liver. In summary, our data demonstrate that, in addition to the well-described platelet defects in GPS, there are also immune defects. The abnormal immune cells may be the drivers of systemic abnormalities, such as autoimmune disease.

Gray platelet syndrome (GPS) is a rare recessive disorder caused by biallelic variants in NBEAL2 and characterized by bleeding symptoms, the absence of platelet α-granules, splenomegaly, and bone marrow (BM) fibrosis. Due to the rarity of GPS, it has been difficult to fully understand the pathogenic processes that lead to these clinical sequelae. To discern the spectrum of pathologic features, we performed a detailed clinical genotypic and phenotypic study of 47 patients with GPS and identified 32 new etiologic variants in NBEAL2. The GPS patient cohort exhibited known phenotypes, including macrothrombocytopenia, BM fibrosis, megakaryocyte emperipolesis of neutrophils, splenomegaly, and elevated serum vitamin B12 levels. Novel clinical phenotypes were also observed, including reduced leukocyte counts and increased presence of autoimmune disease and positive autoantibodies. There were widespread differences in the transcriptome and proteome of GPS platelets, neutrophils, monocytes, and CD4 lymphocytes. Proteins less abundant in these cells were enriched for constituents of granules, supporting a role for Nbeal2 in the function of these organelles across a wide range of blood cells. Proteomic analysis of GPS plasma showed increased levels of proteins associated with inflammation and immune response. One-quarter of plasma proteins increased in GPS are known to be synthesized outside of hematopoietic cells, predominantly in the liver. In summary, our data show that, in addition to the well-described platelet defects in GPS, there are immune defects. The abnormal immune cells may be the drivers of systemic abnormalities such as autoimmune disease. ispartof: BLOOD vol:136 issue:17 pages:1956-1967 ispartof: location:United States status: published

The heritable thrombocytopenias (HTs) are genetically heterogeneous rare disorders in whichreduced circulating platelet levels may be associated with nonhematological features. Amongrecently discovered HTs, DIAPH1-related disorder (D-RD; OMIM #124900) was initially reported in pedigrees with macrothrombocytopenia and hearing loss. This phenotype segregated with aheterozygous p.R1213* variant in DIAPH1, which encodes the cytoskeletal regulator diaphanoushomolog 1 (DIAPH1). This predicted truncation of the DIAPH1 C terminus diaphanous autoregulatory domain (DAD) and was proposed to confer gain-of-function, resulting in megakaryocyte (MK) cytoskeletal dysregulation and impaired proplatelet formation. Macrothrombocytopenia and hearing loss have subsequently been reported in further isolated pedigrees with DAD DIAPH1 variants,4-6 suggesting that D-RD is a distinct syndromic HT. However, other descriptions of similar DIAPH1 variants include hearing loss but not hematological findings. To provide a full phenotypic description of D-RD and the relationship with different DIAPH1 variants, we report detailed hematological findings from 5 D-RD pedigrees, including the in vitro response and clinical outcome of treatment with the thrombopoietin (TPO) receptor agonisteltrombopag.

Chronic Lymphocytic Leukaemia (CLL), the most common leukaemia in the Western world, has a characteristic phenotype and prognosis largely defined by the presence of cytogenetic aberrations. The gold standard for detecting these cytogenetic abnormalities is interphase fluorescence in situ hybridisation (FISH) performed on cell smears or tissue sections on glass slides. Fluorescently labelled DNA probes bind to specific chromosomal regions and the signal detected by fluorescent microscopy. Generally only 200 cells are assessed and the limit of sensitivity is 3% positive cells. Here we report the development and use of imaging flow cytometry to assess chromosomes by FISH in phenotyped CLL cells in suspension. Thousands of CLL cells, identified by their phenotype, are assessed for specific FISH probe signals using an automated, high throughput imaging flow cytometer. The "extended depth of field" capability of the imaging flow cytometer enables FISH probe signals ("spots") to be resolved and localised within the (stained) nucleus of the immunophenotyped cells. We report the development of the automated "immuno-flowFISH" on normal blood using the Amnis ImageStreamX mark II platform and illustrate the clinical application of the method for the assessment of chromosome 12 in CLL. It is a powerful new method which has potential to be applied at diagnosis for disease stratification, and following treatment to assess residual disease. These applications will assist clinicians in optimising therapeutic decision making and thereby improve patient outcome.

Platelets are subcellular blood elements with a well-established role in haemostasis. Upon activation platelets undergo granule exocytosis, resulting in α-granule P-Selectin being expressed on the cell membrane. This allows binding of activated platelets to P-Selectin glycoprotein ligand 1 (PSGL-1) expressing leukocytes, forming leukocyte-platelet aggregates (LPAs). Whole blood flow cytometry (FCM) has demonstrated that elevated circulating LPAs (especially monocyte LPAs) are linked to atherothrombosis in high risk patients, and that activated platelet binding influences monocytes towards a pro-adhesive and pro-atherogenic phenotype. However, a limitation of conventional FCM is the potential for coincident events to resemble LPAs despite no tethering. Imaging cytometry can be used to characterize LPA formation and distinguish circulating MPAs from coincidental events. Platelets and leukocyte subsets are identified by expression of surface markers (e.g. the lipopolysachharide receptor CD14 on monocytes, glycoprotein Ib CD42b on platelets). In conventional FCM, all events with both leukocyte and platelet characteristics are designated as LPAs. However, by using an 'internal' mask based on the brightfield image and the fluorescent platelet identifier, imaging flow cytometry is able to distinguish leukocytes with tethered platelets (genuine LPAs) from leukocyte with coincidental, untethered platelets nearby. Mechanisms (e.g. adhesion molecules) or consequences (e.g. signal transduction) can then be separately analysed in platelet tethered and untethered leukocytes. Imaging flow cytometry therefore provides a more accurate approach for both enumeration and analysis of LPAs than conventional FCM.

Del(17p) in chronic lymphocytic leukemia (CLL) and plasma cell myeloma has a unique genomic profile leading to refractoriness to conventional therapies and poor overall survival. Detection is generally by fluorescence in situ hybridization (FISH) on a slide with analysis of up to 200 nuclei, not necessarily all of being neoplastic cells. The small cell sample analyzed, and high threshold for a positive result (>5% positive cells) makes FISH a low precision test. This means false negative results are inevitable, especially if del(17p) is only in a minor clone, potentially leading to suboptimal treatment. To address this, we developed an automated FISH method with analysis on an imaging flow cytometer, an instrument with the functionality of a standard flow cytometer which generates high-resolution digital images of each cell. By combining immunophenotyping with FISH, on whole cells in a single test, we can detect chromosomal defects in cells with a specific phenotype. Aims: Our aim was to determine the capability of this automated integrated immunophenotyping-FISH imaging flow cytometry method to detect del(17p) in CLL and myeloma, the two commonest hematological malignancies, and in which this genetic defect encodes poor prognosis. We hypothesized that it would be more sensitive and specific than standard FISH. Methods: Bone marrow and/or blood samples in EDTA anticoagulant from 19 cases of CLL or myeloma, at diagnosis or on therapy, were studied. After red cell lysis, cells were incubated with fluorochrome-conjugated antibodies to CD3, CD5, CD19, CD38, and CD138 antigens (fluorochromes: BV480, BV605, AF647). Following fixation, cell membranes were permeabilized and double-stranded DNA denatured (78oC for 5 mins). FISH probes to the centromere of chromosome 17 (CEP17, Spectrum Green) and 17p12 locus (Orange-Red) were added and hybridized for 24 hours at 37oC. Nuclei were stained with SYTOX AADvanced. Data for up to 200,000 cells was collected on the Amnis® ImageStream®XMk II imaging flow cytometer. Digital images (x60) and quantitative data derived from computational algorithms (IDEAS software) were used to assess FISH signals overlying the nuclei of CD5/CD19-positive CLL cells or CD38/CD138-positive plasma cells for each probe. Digital images and quantitative data were assessed for FISH signals within immunophenotyped cells. Results: Between 10,000 and 200,000 (mean 60,000) cells were analyzed per sample. The FISH signals were seen on the digital images and confirmed by quantitative mean channel fluorescence intensity of the probes. There were 12 CLL cases with one 17p FISH signal in the CD5/CD19-positive population, with the number of del(17p) CLL cells ranging from 2 - 35% (or 0.4 - 23% of all cells analyzed) (Fig 1). This amounted to between 270 and 35,441 cells in the analysed sample with del(17p). The lowest del(17p) burden was in a patient on cytoreductive therapy. All CLL cells had normal diploid spots for the control CEP17 probe, and the CD3/CD5-positive T cells had dual signals for both CEP17 and 17p12 probes. There were 5 myeloma cases with 1 FISH signal for 17p overlying the nucleus of the CD38/CD138-positive plasma cells (Fig 2). In these cases, 52-90% of cells (15,600-18,000 cells) had a plasma cell phenotype and 13-19% of these (or 2,340-2,964 CD38/CD138-positive cells) showed del(17p). This represented 1-5% of all cells in the sample. All gated plasma cells had 2 FISH spots for CEP17. Conclusion: This imaging flow cytometry method that integrates FISH with immunophenotyping could detect del(17p) in CLL and myeloma with a lowest limit of detection of 0.4% and 1% respectively. The high sensitivity was achieved as many thousands of cells were analyzed, and 17p was only assessed in gated cells with the phenotype of interest (i.e. CD5/CD19 or CD38/CD138). This method, that includes positive cell identification by phenotype, precludes the need for prior cell sorting or purification. Imaging flow cytometry for del(17p) by "immuno-flowFISH" brings a new dimension to FISH analysis at diagnosis and for disease monitoring. Its high precision and specificity will enable detection of del(17p), even when only present in minor sub-clones, for therapeutic decision making and prognostic stratification. This technique has a real place in clinical assessment of del(17p) in CLL and myeloma and could be applied for other significant chromosomal defects of therapeutic and prognostic significance. Figure 1 Disclosures Augustson: Roche: Other: Support of parent study and funding of editorial support. Cheah:Celgene, F. Hoffmann-La Roche, Abbvie, MSD: Research Funding; Celgene, F. Hoffmann-La Roche, MSD, Janssen, Gilead, Ascentage Pharma, Acerta, Loxo Oncology, TG therapeutics: Honoraria.

Aims Megakaryocyte expansion in myeloproliferative neoplasms (MPNs) is due to uncontrolled proliferation accompanied by dysregulation of proapoptotic and antiapoptotic mechanisms. Here we have investigated the intrinsic and extrinsic apoptotic pathways of megakaryocytes in human MPNs to further define the mechanisms involved. Methods The megakaryocytic expression of proapoptotic caspase-8, caspase-9, Diablo, p53 and antiapoptotic survivin proteins was investigated in bone marrow specimens of the MPNs (n=145) and controls (n=15) using immunohistochemistry. The megakaryocyte percentage positivity was assessed by light microscopy and correlated with the MPN entity, JAK2 V617F / CALR mutation status and platelet count. Results The proportion of megakaryocytes in the MPNs expressing caspase-8, caspase-9, Diablo, survivin and p53 was significantly greater than controls. A greater proportion of myeloproliferative megakaryocytes expressed survivin relative to its reciprocal inhibitor, Diablo. Differences were seen between myelofibrosis, polycythaemia vera and essential thrombocythaemia for caspase-9 and p53. CALR -mutated cases had greater megakaryocyte p53 positivity compared to those with the JAK2 V617F mutation. Proapoptotic caspase-9 expression showed a positive correlation with platelet count, which was most marked in myelofibrosis and CALR -mutated cases. Conclusions Disruptions targeting the intrinsic apoptotic cascade promote megakaryocyte hyperplasia and thrombocytosis in the MPNs. There is progressive dysfunction of apoptosis as evidenced by the marked reduction in proapoptotic caspase-9 and accumulation of p53 in myelofibrosis. The dysfunction of caspase-9, which is necessary for proplatelet formation, may be the mechanism for the excess thrombocytosis associated with CALR mutations. Survivin seems to be the key protein mediating the megakaryocyte survival signature in the MPNs and is a potential therapeutic target.

BackgroundTransforming growth factor α (TGFα) is a peptide growth factor known to be expressed in normal haemopoiesis. It is also expressed in a range of epithelial neoplasms but has not been assessed in haemopoietic malignancies. We have performed an immunohistochemical evaluation of TGFα in acute and chronic myeloid malignancies.MethodsTGFα expression was semiquantitatively assessed in 69 normal bone marrow trephines and 157 cases of myeloid malignancy using an immunohistochemical approach.ResultsBlast cells of myeloid origin in acute myeloid leukaemia (AML), myelodysplasia and accelerated and blast phases of chronic myeloid leukaemia (CML) were TGFα positive. In acute promyelocytic leukaemia the neoplastic cells had significantly weaker TGFα expression than seen in other forms of AML. The blast cells in CML-accelerated and blast phases were positive with similar expression to AML.ConclusionsTGFα is expressed in neoplastic myeloblasts and could, therefore, be used as blast cell biomarker in diagnostic haematopathology. In addition, TGFα immunohistochemistry may be of use in identifying a therapeutic target.

Without effective therapy, chronic-phase chronic myeloid leukemia (CP-CML) evolves into an acute leukemia (blast crisis [BC]) that displays either myeloid or B-lymphoid characteristics. This transition is often preceded by a clinically recognized, but biologically poorly characterized, accelerated phase (AP). Here, we report that IKAROS protein is absent or reduced in bone marrow blasts from most CML patients with advanced myeloid disease (AP or BC). This contrasts with primitive CP-CML cells and BCR-ABL1-negative acute myeloid leukemia blasts, which express readily detectable IKAROS. To investigate whether loss of IKAROS contributes to myeloid disease progression in CP-CML, we examined the effects of forced expression of a dominant-negative isoform of IKAROS (IK6) in CP-CML patients' CD34(+) cells. We confirmed that IK6 disrupts IKAROS activity in transduced CP-CML cells and showed that it confers on them features of AP-CML, including a prolonged increased output in vitro and in xenografted mice of primitive cells with an enhanced ability to differentiate into basophils. Expression of IK6 in CD34(+) CP-CML cells also led to activation of signal transducer and activator of transcription 5 and transcriptional repression of its negative regulators. These findings implicate loss of IKAROS as a frequent step and potential diagnostic harbinger of progressive myeloid disease in CML patients.

Platelets are subcellular blood elements with a well-established role in haemostasis. Upon activation platelets express P-Selectin (CD62P) on the cell membrane and bind to P-Selectin glycoprotein ligand 1 expressing monocytes, influencing them toward a pro-adhesive and inflammatory phenotype. It is well established that elevated circulating monocyte-platelet aggregates (MPAs) are linked to atherothrombosis in high risk patients. However, whole blood flow cytometry (FCM) has recently shown that circulating MPAs may also occur in the absence of platelet activation, particularly in healthy children. A potential limitation of conventional FCM is the potential for coincident events to resemble monocyte platelet aggregates. Here we report a novel imaging cytometry approach to further characterize monocyte-platelet aggregate formation by P-Selectin dependent and P-Selectin independent mechanisms and distinguish circulating MPAs from coincidental events. Monocytes were identified by expression of the lipopolysachharide receptor (CD14 BV421), while platelets were identified by expression of the glycoprotein Ib (CD42b APC). Differentiation of P-Selectin dependent and P-Selectin independent binding was achieved with AF488 labeled CD62P. Overall analysis of circulating and in vitro generated MPAs by conventional and imaging cytometry methods showed very strong correlation (r2 = >0.99, P

B-cell chronic lymphoproliferative disorders (B-CLPD) encompass a group of hematologic tumors that often present with leukemic involvement.1 Their heterogeneity and the lack of relatively specific diagnostic markers for most of these diseases make their diagnosis challenging, especially in cases that only have blood involvement or when histology is not available. With the currently used immunophenotypic and molecular markers, around 10% of B-CLPD cases remain unclassifiable and are categorized as B-CLPD, not otherwise specified (B-CLPD, NOS).

Myeloproliferative neoplasms (MPNs) are a group of related clonal hemopoietic stem cell disorders associated with hyperproliferation of myeloid cells. They are driven by mutations in the hemopoietic stem cell, most notably JAK2V617F, CALR, and MPL. Clinically, they have the propensity to progress to myelofibrosis and transform to acute myeloid leukemia. Megakaryocytic hyperplasia with abnormal features are characteristic, and it is thought that these cells stimulate and drive fibrotic progression. The biological defects underpinning this remain to be explained. In this study we examined the megakaryocyte genome in 12 patients with MPNs to determine whether there are somatic variants and whether there is any association with marrow fibrosis. We performed targeted next-generation sequencing for 120 genes associated with myeloid neoplasms on megakaryocytes isolated from aspirated bone marrow. Ten of the 12 patients had genomic defects in megakaryocytes that were not present in nonmegakaryocytic hemopoietic marrow cells from the same patient. The greatest allelic burden was in patients with increased reticulin deposition. The megakaryocyte-unique mutations were predominantly in genes that regulate chromatin remodeling, chromosome alignment, and stability. These findings show that genomic abnormalities are present in megakaryocytes in MPNs and that these appear to be associated with progression to bone marrow fibrosis.

Angiogenesis plays a pivotal role in bone formation, remodeling, and fracture healing. The regulation of angiogenesis in the bone microenvironment is highly complex and orchestrated by intercellular communication between bone cells and endothelial cells. Here, we report that EGF-like domain 7 (EGFL7), a member of the epidermal growth factor (EGF) repeat protein superfamily is expressed in both the osteoclast and osteoblast lineages, and promotes endothelial cell activities. Addition of exogenous recombinant EGFL7 potentiates SVEC (simian virus 40-transformed mouse microvascular endothelial cell line) cell migration and tube-like structure formation in vitro. Moreover, recombinant EGFL7 promotes angiogenesis featuring web-like structures in ex vivo fetal mouse metatarsal angiogenesis assay. We show that recombinant EGFL7 induces phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), signal transducer and activator of transcription 3 (STAT3), and focal adhesion kinase (FAK) in SVEC cells. Inhibition of ERK1/2 and STAT3 signaling impairs EGFL7-induced endothelial cell migration, and angiogenesis in fetal mouse metatarsal explants. Bioinformatic analyses indicate that EGFL7 contains a conserved RGD/QGD motif and EGFL7-induced endothelial cell migration is significantly reduced in the presence of RGD peptides. Moreover, EGFL7 gene expression is significantly upregulated during growth plate injury repair. Together, these results demonstrate that EGFL7 expressed by bone cells regulates endothelial cell activities through integrin-mediated signaling. This study highlights the important role that EGFL7, like EGFL6, expressed in bone microenvironment plays in the regulation of angiogenesis in bone.

Mutations in the C-terminal region of nucleophosmin in acute myeloid leukemia (AML) result in aberrant cytoplasmic nucleophosmin (cNPM) in leukemic blast cells which is detectable by immunocytochemistry in bone marrow trephine (BMT) biopsy sections. We tested whether cNPM is detectable by immunocytochemistry in air-dried smears of AML with nucleophosmin1 (NPM1) mutations. An immunoalkaline phosphatase method was developed using the OCI-AML3 cell line, known to have mutated NPM1, and assessed on blood and marrow smears of 60 AML cases. NPM was detectable in all blast cell nucleoli and cNPM in 21 of 31 of NPM1 mutated and 15 of 29 wild-type cases. Paired air-dried smears and BMT biopsies from the same case (mutated and wild-type) gave discrepancies in cNPM expression and there was no correlation in 10 of 22 cases. Due to the high false positive and negative rates for cNPM in cell smears, this method should not be used as a surrogate for NPM1 mutations in AML.

The Src family kinase (SFK) member SRC is a major target in drug development because it is activated in many human cancers, yet deleterious SRC germline mutations have not been reported. We used genome sequencing and Human Phenotype Ontology patient coding to identify a gain-of-function mutation in SRC causing thrombocytopenia, myelofibrosis, bleeding, and bone pathologies in nine cases. Modeling of the E527K substitution predicts loss of SRC's self-inhibitory capacity, which we confirmed with in vitro studies showing increased SRC kinase activity and enhanced Tyr(419) phosphorylation in COS-7 cells overexpressing E527K SRC. The active form of SRC predominates in patients' platelets, resulting in enhanced overall tyrosine phosphorylation. Patients with myelofibrosis have hypercellular bone marrow with trilineage dysplasia, and their stem cells grown in vitro form more myeloid and megakaryocyte (MK) colonies than control cells. These MKs generate platelets that are dysmorphic, low in number, highly variable in size, and have a paucity of α-granules. Overactive SRC in patient-derived MKs causes a reduction in proplatelet formation, which can be rescued by SRC kinase inhibition. Stem cells transduced with lentiviral E527K SRC form MKs with a similar defect and enhanced tyrosine phosphorylation levels. Patient-derived and E527K-transduced MKs show Y419 SRC-positive stained podosomes that induce altered actin organization. Expression of mutated src in zebrafish recapitulates patients' blood and bone phenotypes. Similar studies of platelets and MKs may reveal the mechanism underlying the severe bleeding frequently observed in cancer patients treated with next-generation SFK inhibitors. ispartof: Science Translational Medicine vol:8 issue:328 pages:328- ispartof: location:United States status: published

Mutations within the nucleophosmin NPM1 gene occur in approximately one-third of cases of acute myeloid leukemia (AML). These mutations result in cytoplasmic accumulation of the mutant NPM protein. NPM1 mutations are currently detected by molecular methods. Using samples from 37 AML patients, we investigated whether imaging flow cytometry could be a viable alternative to this current technique. Bone marrow/peripheral blood cells were stained with anti-NPM antibody and DRAQ5 nuclear stain, and data were acquired on an ImageStream imaging flow cytometer (Amnis Corp., Seattle, USA). Using the similarity feature for data analysis, we demonstrated that this technique could successfully identify cases of AML with a NPM1 mutation based on cytoplasmic NPM protein staining (at similarity threshold of 1.1 sensitivity 88% and specificity 90%). Combining data of mean fluorescence intensity and % dissimilar staining in a 0-2 scoring system further improved the sensitivity (100%). Imaging flow cytometry has the potential to be included as part of a standard flow cytometry antibody panel to identify potential NPM1 mutations as part of diagnosis and minimal residual disease monitoring. Imaging flow cytometry is an exciting technology that has many possible applications in the diagnosis of hematological malignancies, including the potential to integrate modalities.

The JAK2 V617F mutation is present in the majority of patients with a myeloproliferative neoplasm (MPN) and is sufficient to recapitulate an MPN in murine models. However, the consequences of JAK2 mutations for myeloid differentiation are poorly understood. After systematic analyses of a large cohort of JAK2-mutated MPN patients, we demonstrate in vivo that JAK2 mutations do not alter hematopoietic stem and progenitor cell com-partment size or in vitro behavior but generate expansion of later myeloid differentiation compartments, where homozygous expression of the mutation confers an added proliferative advantage at the single-cell level. In addition, we demonstrate that these findings may be partially explained by the expression pattern of JAK2, which markedly increases on myeloid differentiation. Our findings have potential clinical relevance, as they predict that JAK2 inhibitors may control myeloproliferation, but may have limited efficacy in eradicating the leukemic stem cells that sustain the human MPN.

Acute promyelocytic leukaemia (APML) can be promptly diagnosed by detecting abnormal diffuse staining patterns of PML bodies in abnormal promyelocytes using immunofluorescence microscopy. However, this technique is subjective, with low sensitivity. Using samples from 18 patients with acute myeloid leukaemia (AML) (including four with APML), the authors investigated whether imaging flow cytometry could be a viable alternative to this current technique and improve sensitivity levels. Bone marrow/peripheral blood cells were stained with an antibody to PML, and data were acquired on an ImageStream (Amnis Corporation, Seattle, Washington, USA). Using the modulation feature for data analysis, the authors demonstrated that this technique could successfully identify cases of APML. Imaging flow cytometry, by analysing greater numbers of cells and with the potential to include disease-specific antigens, increases the sensitivity of the current immunofluorescence technique. Imaging flow cytometry is an exciting technology that has many possible applications in the diagnosis of haematological malignancies, including the potential to integrate modalities.

Myelodysplastic Syndromes (MDS) are a heterogeneous group of acquired clonal bone marrow disorders, characterised by ineffective hematopoiesis. The mechanisms underlying many of these blood disorders have remained elusive due to the difficulty in pinpointing specific gene mutations or haplo-insufficencies, which can occur within large deleted regions. However, there is an increasing interest in the classification of some of these diseases as ribosomopathies. Indeed, studies have implicated Ribosomal Protein (RP) S14 as a strong candidate for haploinsufficiency in 5q- syndrome, a particular form of MDS. Recently, two novel mouse models have provided evidence for the involvement of both RPS14 and the p53 pathway, and specific miRNAs in 5q- syndrome. In this review we will discuss: 5q- syndrome mouse models, the possible mechanisms underlying this blood disorder with respect to the candidate genes and comparisons with other ribosomopathies and the involvement of the p53 pathway in these diseases.

A 9-yr-old boy with a 2-yr history of Fanconi anaemia developed worsening pancytopenia that was unresponsive to oxymetholone therapy. Bone marrow was difficult to aspirate but showed the presence of megakaryoblasts. Bone marrow trephine was hypercellular with large clusters of abnormal megakaryocytes and a small population of megakaryoblasts, giving a diagnosis of megakaryoblastic leukaemia.

Background and Objectives Idiopathic erythrocytosis (IE) is characterized by erythrocytosis in the absence of megakaryocytic or granulocytic hyperplasia, and is associated with variable serum erythropoietin (Epo) levels. Most patients with IE lack the JAK2 V617F mutation that occurs in the majority of polycythemia vera patients. Four novel JAK2 mutant alleles have recently been described in patients with V617F-negative myeloproliferative disorders presenting with erythrocytosis. The aims of this study were to assess the prevalence of JAK2 exon 12 mutations in IE patients, and to determine the associated clinicopathological features. Design and Methods A cohort of 58 IE patients with low to normal serum Epo levels and no known causative mutation were identified from 181 individuals diagnosed with IE. Patients’ DNA samples were screened for the presence of a JAK2 exon 12 mutation by allele-specific polymerase chain reaction and sequencing. Bone marrow trephines were examined for morphological abnormalities and the erythroid activity assessed immunohistochemically. Results Eight mutation-positive cases were identified, including one with a previously undescribed mutant JAK2 exon 12 allele and another with biallelic involvement. The hematologic features of mutation-positive and mutation-negative patients were similar, although Epo-hypersensitive erythroid progenitors occurred exclusively in patients with an exon 12 mutation ( p =0.0002; n=15). Patients’ bone marrows were moderately hypercellular, as the result of erythroid hyperplasia, and several had mild megakaryocyte atypia. Interpretation and Conclusions JAK2 exon 12 mutations were detected in 27% of patients with low serum Epo levels, all of whom had Epo-independent erythroid progenitors. Consequently, IE patients presenting with either of these features should be tested for the presence of a JAK2 mutation.

BIOMED-2 polymerase chain reaction (PCR) assays for clonality analysis of immunoglobulin (IG) and T-cell receptor (TCR) gene rearrangements were evaluated in routine haematopathological practice where paraffin-embedded tissues constitute the majority of specimens. One hundred and twenty-five fresh/frozen and 316 paraffin specimens were analysed for DNA quality and clonality. Seventy-nine per cent of paraffin specimens yielded PCR products of over 300 bp. These specimens and all fresh/frozen specimens were analysed with the complete set of BIOMED-2 reactions for IG (8 reactions) and/or TCR (6 reactions) gene rearrangements. The rate of detection of clonality was 96% in mature B-cell neoplasms and 98% in mature T-cell neoplasms and there were no significant differences in these rates between paraffin and fresh/frozen specimens. As the value of sole use of any individual BIOMED-2 reaction in clonality detection was limited, we assessed combinations of reactions that gave the greatest sensitivity with fewest reactions and were applicable for both fresh/frozen and paraffin specimens. For IG gene rearrangements, three reactions combining one targeting the IG heavy chain framework-2 region and two targeting the IG kappa locus achieved a 91% detection rate. For TCR gene rearrangements, the two TCR gamma reactions gave a 94% detection rate. We therefore recommend this strategy as the first-line assays for routine B- and T-cell clonality analysis in diagnostic haematopathology.

Aims Myeloproliferative neoplasms (MPN) are a heterogeneous group of clonal proliferative bone marrow diseases characterised by extensive megakaryocytic hyperplasia and morphological atypia. Despite knowledge of genomic defects, the pathobiological processes driving these megakaryocytic abnormalities in MPN remain poorly explained. We have explored the proliferative, apoptotic and epigenetic profiles of megakaryocytes in human MPN. Methods Immunohistochemical staining was performed on bone marrow trephine biopsies of 81 MPN (with and without JAK2 V617F and CALR mutations) and 15 normal controls to assess the megakaryocytic expression of biomarkers associated with proliferation (Ki67), apoptosis (Bcl-XL, BNIP-3) and epigenetic regulation (EZH2, SUZ12). Results Myeloproliferative megakaryocytes showed significantly greater expression of proliferative Ki67 and anti-apoptotic Bcl-XL, reduced pro-apoptotic BNIP-3 and increased SUZ12 compared with controls. In essential thrombocythaemia, large-giant megakaryocytes with hyperlobated nuclei showed a trend towards a proliferative signature. In contrast, myelofibrotic megakaryocytes with condensed nuclear chromatin, and cases with CALR mutations, had significant reductions in pro-apoptotic BNIP-3. Conclusions Uncontrolled megakaryocytic expansion in MPN results from a combination of increased proliferation, attenuated apoptosis and defective epigenetic regulation with CALR mutations favouring apoptotic failure. The higher platelet counts reported to be seen in MPN with CALR mutations may be due to greater dysregulation of megakaryocyte apoptosis.

Blood cells derive from hematopoietic stem cells through stepwise fating events. To characterize gene expression programs driving lineage choice, we sequenced RNA from eight primary human hematopoietic progenitor populations representing the major myeloid commitment stages and the main lymphoid stage. We identified extensive cell type-specific expression changes: 6711 genes and 10,724 transcripts, enriched in non-protein-coding elements at early stages of differentiation. In addition, we found 7881 novel splice junctions and 2301 differentially used alternative splicing events, enriched in genes involved in regulatory processes. We demonstrated experimentally cell-specific isoform usage, identifying nuclear factor I/B (NFIB) as a regulator of megakaryocyte maturation-the platelet precursor. Our data highlight the complexity of fating events in closely related progenitor populations, the understanding of which is essential for the advancement of transplantation and regenerative medicine. The work described in this manuscript was primarily supported by the European Commission Seventh Framework Program through the BLUEPRINT grant with code HEALTH-F5-2011-282510 (DH, FB, GC, JHAM, KD, LC, MF, SC, SF and SPG). Research in the Ouwehand laboratory is further supported by program grants from the National Institute for Health Research (NIHR, http://www.nihr.ac.uk; to AA, MK, PP, SBGJ, SN, and WHO); and the British Heart Foundation under numbers RP-PG-0310-1002 and RG/09/12/28096 (http://www.bhf.org.uk; to AR and WJA). KF and MK were supported by Marie Curie funding from the NETSIM FP7 program funded by the European Commission. The Cambridge BioResource (http://www.cambridgebioresource.org.uk), the Cell Phenotyping Hub, and the Cambridge Translational GenOmics laboratory (http://www.catgo.org.uk) are supported by an NIHR grant to the Cambridge NIHR Biomedical Research Centre (BRC). Research in the Soranzo laboratory (LV, NS and SW) is further supported by the Wellcome Trust (Grant Codes WT098051 and WT091310) and the EU FP7 EPIGENESYS initiative (Grant Code 257082). Research in the Cvejic laboratory (AC and CL) is funded by the Cancer Research UK under grant number C45041/A14953. SJS is funded by NIHR. MEF is supported by a British Heart Foundation Clinical Research Training Fellowship, number FS/12/27/29405. EBM is supported by a Wellcome Trust grant, number 084183/Z/07/Z. FAC, CL and SW are supported by MRC Clinical Training Fellowships and TB by a British Society of Haematology/NHS Blood and Transplant grant. RJR is a Principal Research Fellow of the Wellcome Trust, grant No. 082961/Z/07/Z. Research in the Flicek laboratory is also supported by the Wellcome Trust (grant number 095908) and EMBL. Research in the Bertone laboratory is supported by EMBL. KF and CvG are supported by FWO-Vlaanderen through grant G.0B17.13N

Many catabolic patients can only consume small volumes of enteral nutrients. The aim of this study was to evaluate markers of cellularity and immunity in the small intestine of rats randomized to receive 6 days of parenteral nutrition, 25% enteral and 75% parenteral nutrition (i.e. minimum luminal nutrition) or enteral nutrition. The same glutamine-enriched solution was used for both parenteral and enteral nutrition. Enteral nutrition was associated with the least amount of jejunal atrophy (P

AIMS: The detection of cellular antigens in fixed decalcified bone marrow trephine (BMT) sections depends on the method of processing, the nature of the antigen and antibody, antigen retrieval techniques, and the sensitivity of the immunocytochemical method. This study evaluated a tyramide enhanced avidin-biotin immunostaining method on formalin fixed decalcified BMT sections to determine whether the method could detect previously undetectable antigens. METHODS: Nineteen BMT biopsies from a range of haematological disorders were evaluated with 43 antibodies to haemopoietic antigens using horseradish peroxidase and alkaline phosphatase detection methods, using the tyramide enhanced avidin-biotin immunostaining method. RESULTS: Compared with standard avidin-biotin immunostaining methods the tyramide enhanced immunostaining method showed enhanced signal intensity, gave positive labelling for antigens that require pretreatment by other methods, and previously unreactive antigens were detected. Primary antibodies could be used at up to 200 times higher dilutions. CONCLUSION: The tyramide enhanced immunostaining method, while retaining specificity, is highly sensitive and enables an increased number and range of antigens to be detected than previously possible. The method could be applied to BMT sections for the routine diagnosis and classification of haematological disorders.

FFP has occasionally been reported to generate an immune response to RBC antigens (e.g., anti-D and anti-Fya). The Council of Europe requires that each unit of FFP have less than 6 × 109/L RBCs. However, there is considerable variation internationally in the method of production and the level and assessment of RBC contamination of FFP. This study reports the case of a 63-year-old group B, D– man who received multiple transfusions of D– blood products over a 4-month period. Seven months later the patient’s antibody screen remained negative and he was transfused with seven units of D– RBCs and six units of FFP, four of which were D+. Two months later anti-D, -E, and -K were detected in his plasma. Although the anti-E and anti-K could have resulted from transfusion of antigen-positive RBCs, the anti-D could have resulted only from transfusion of the D+ FFP. The D status of FFP is currently not considered when selecting products for transfusion even though the D antigen is highly immunogenic and the level of RBC contamination of FFP is not always known. This case highlights that transfusion of FFP is a stimulus for RBC antibodies and that when a patient has had a recent transfusion of FFP, consideration should be given to obtaining a sample for pretransfusion testing within 3 days before a scheduled RBC transfusion. In addition, the D status of FFP should be considered before administering FFP to premenopausal D– women. Immunohematology 2005;21:149–51.

Anaplastic large cell lymphoma (ALCL) is a T-cell lymphoma in which the majority of patients present with advanced stage III or IV disease. Here we report a case of ALCL where bone marrow was the only site of disease, in a 60-year-old man with pyrexia and pancytopenia. The diagnosis of ALCL was made on detection of CD30-positive anaplastic cells in the bone marrow, together with prominent hemophagocytosis. Genetics confirmed the clonal nature of the disease and showed it to be anaplastic lymphoma kinase (ALK) negative. Primary isolated bone marrow ALCL should be considered in the diagnosis of pancytopenia associated with hemophagocytosis.

Immunophenotyping is the method by which antibodies are used to detect cellular antigens in clinical samples. Although the major role is in the diagnosis and classification of haematological malignancies, applications have expanded over the past decade. Immunophenotyping is now used extensively for disease staging and monitoring, to detect surrogate markers of genetic aberrations, to identify potential immuno-therapeutic targets and to aid prognostic prediction. This expansion in applications has resulted from developments in antibodies, methodology, automation and data handling. In this review we describe recent advances in both the technology and applications for the analysis of haematological malignancies. We highlight the importance of the expanding repertoire of testing capability for diagnostic, prognostic and therapeutic applications. The impact and significance of immunophenotyping in the assessment of haematological neoplasms are evident.

Although many cell models of multidrug resistance (MDR) have been developed, most have been high-resistance models which generate up to 100-fold increases in drug resistance. However, the drug concentrations required to achieve these levels of resistance are much higher than those found in vivo. In this paper we describe the development of a cell model that reflects the resistance levels that are likely to be found clinically. We then investigated the methods used to detect MDR1 expression at these low levels of drug resistance. We demonstrated that the immunological and PCR-based methods are unable to detect increased MDR1 expression in cells with a < 5.2- and 6.5-fold increase in vinblastine resistance, respectively, in our drug-resistant sublines. The rhodamine 123 (Rh 123) efflux assay was able to discriminate the vinblastine-sensitive parent cells from all the vinblastine-resistant sublines, including cells with a 1.7-fold increase in resistance. However, this assay is non-specific to the MDR1 gene and may detect the activity of other drug efflux proteins such as the MDR-associated protein (MRP). Our results show that the Rh 123 efflux assay is able to detect the activity of drug efflux proteins such as the P-glycoprotein, MRP or other efflux systems at the low levels of drug resistance that are likely to be attained in vivo.

Summary Previous studies have demonstrated upregulation of intestinal mucosal macrophage CD16 (an Fc receptor for IgG) in bone marrow transplant (BMT) recipients with graft-versus-host disease (GVHD). We sought to determine whether there was ultrastructural evidence of mucosat macrophage activation in allogeneic BMT recipients and relate appearances to those seen in autologous BMT patients and to immunohistological findings. Sigmoid colonic mucosal biopsies from five allogeneic and three autologous BMT patients were taken prior to, 30 days after transplant and, in three of the allogeneic patients, 120 days after transplant. These were examined by immunohisto-chemistry and electron microscopy. Immunohistological analysis revealed upregulation of lamina propria macrophage CD16 after transplant in all patients except one autologous BMT recipient; there were no such changes in total macrophage numbers. Ultrastructural evidence of lamina propria macrophage activation was prominent after both allogeneic and autologous BMT. There was an increase in nuclear size accompanied by increased euchromatin and larger nucleoli. In the cytoplasm there were increased numbers of lysosomes, many of which were small and cylindrical, and cytoplasmic flaps were prominent. Phagosomes were less numerous after transplant. These data confirm that after BMT intestinal mucosal macrophages become activated. However changes in macrophage uttrastructure specific to patients at risk of developing clinical GVHD are lacking.

Angiogenesis plays an important role in physiological bone growth and remodeling, as well as in pathological bone disorders such as fracture repair, osteonecrosis, and tumor metastasis to bone. Vascularization is required for bone remodeling along the endosteal surface of trabecular bone or Haversian canals within the cortical bone, as well as the homeostasis of the cartilage-subchondral bone interface. Angiogenic factors, produced by cells from a basic multicellular unit (BMU) within the bone remodeling compartment (BRC) regulate local endothelial cells and pericytes. In this review, we discuss the expression and function of angiogenic factors produced by osteoclasts, osteoblasts and osteocytes in the BMU and in the cartilage-subchondral bone interface. These include vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), BMP7, receptor activator of NF-κB ligand (RANKL) and epidermal growth factor (EGF)-like family members. In addition, the expression of EGFL2, EGFL3, EGFL5, EGFL6, EGFL7, EGFL8 and EGFL9 has been recently identified in the bone local environment, giving important clues to their possible roles in angiogenesis. Understanding the role of angiogenic factors in the bone microenvironment may help to develop novel therapeutic targets and diagnostic biomarkers for bone and joint diseases, such as osteoporosis, osteonecrosis, osteoarthritis, and delayed fracture healing.

Leukemic B-cell chronic lymphoproliferative disorders (B-CLPD) encompass a heterogeneous group of defined disease entities. However, around 10% of the cases cannot be reliably classified based on the current criteria and are considered B-CLPD not otherwise specified (B-CLPD NOS). Few recurrent mutations and genetic alterations have been reported in some entities, but none is specific. We performed gene expression profiling (GEP) to develop a robust GEP-molecular classifier for leukemic B-CLPD. We analyzed purified blood of 189 B-CLPD, including 54 chronic lymphocytic leukemia (CLL), 54 mantle cell lymphoma (MCL), 12 follicular lymphoma (FL), 23 splenic marginal zone lymphoma (SMZL), 4 splenic diffuse red pulp lymphoma (SDRPL), 4 hairy cell leukemia (HCL), 4 HCL-variant (HCL-v), 6 lymphoplasmacytic lymphoma (LPL) and 28 B-CLPD NOS. We used a multiple step approach to build a GEP-array classifier and then analyzed an additional series as a validation cohort by quantitative PCR (qPCR). Mutational analysis of BRAF, MAP2K1, MYD88, NOTCH1, NOTCH2, SF3B1 and TP53 and copy number alterations were studied. In the training set, a supervised analysis clustering revealed that each B-CLPD entity has a specific expression profile. By a multi-step GEP classifier using 43 genes ( Table 1 ) we could classify CLL, SOX11-positive MCL (MCLc), HCL, FL, SOX11-negative MCL (MCLi) and HCL-v cases in six successive stages. However, we were not able to clearly identify distinct signatures for LPL, SMZL and SDRPL. Furthermore, we could classify 36% of B-CLPD NOS cases. Interestingly, the 43-gene signature identified in leukemic samples could also classify the 28 tumor splenic biopsies. Finally, we built a simple 8-gene predictive model using qPCR data ( including: FMOD, KSR2, SOX11, MYOF, MME, CCND1, CXCR4, and CAMSAP2 ) that was used in an independent validation cohort and classified 14% B-CLPD NOS cases. The classification yield increased to 61% and 50%, for GEP-array and qPCR, respectively, when additional morphological, molecular and genetic features were considered. Our findings support the use in a routine base of a simple test as a diagnostic tool that can be applied to help multiparameter interpretation in the classification of leukemic B-CLPD and specially B-CLPD NOS. | Step model | B-CLPD | Specific signatures | | ---------- | ----------------------------------- | ------------------------------------------------------------------------------------------------------------------ | | 1 | CLL | FMOD, KSR2 , ADTRP, CLNK, LEF1, FILIP1L, CTLA4, IGSF3, EBF1 | | 2 | MCLc | SOX11 , PLEKHG4B, HDGFRP3, CNN3, PON2, SH3BP4, FCGBP, STMN1, FARP1, DBN1, NREP, NINL, MARCKSL1, MEX3D, CRIM1, KAZN | | 3 | HCL | HPGDS, IL1R2, TJP1, PLOD2, EMP1, NOVA1 | | 4 | FL | MME , SLC2A5, SMAD1, PRDM15 | | 5 | MCLi | CCND1 | | 6 | HCL-v | TUSC1, LRP1B, KCNJ3, NRCAM, MS4A14, FAM129C, CXCR4 | | 7 | Miscellaneous LPL-SDRPL-SMZL | No specific genes | Table 1. Gene signatures (43 genes) and steps used for the GEP-array model. CLL: chronic lymphocytic leukemia; FL: follicular lymphoma, HCL: hairy cell leukemia; HCL-v: hairy cell leukemia variant; LPL, lymphoplasmacytic lymphoma; MCLc: conventional SOX11-positive mantle cell lymphoma; MCLi: indolent SOX11-negative mantle cell lymphoma; SDRPL, splenic diffuse red pulp lymphoma; SMZL, splenic marginal zone lymphoma. Bold letters indicate some of the genes included in the simple qPCR model. Disclosures Lopez-Guillermo: Roche, Celgene, Mundipharma, Gilead, Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Twenty-one cases of acute promyelocytic leukaemia (FAB M3) demonstrating t(15,17) chromosomal translocation were studied in detail by immunocytochemical techniques using a panel of monoclonal antibodies. A characteristic myeloid phenotype of the leukaemic cells, co-expression of CD9 and CD68 antigens and absence of HLA-DR, was noted in all cases. Although the cellular morphology of acute promyelocytic leukaemia provides the most rapid means for diagnosis, this unique leukaemic cell phenotype provides confirmatory diagnostic evidence. In view of the new therapeutic options and prognosis in acute promyelocytic leukaemia, the detection of cases with atypical morphology based on this unique phenotype would be of value. In addition, the phenotype of acute promyelocytic leukaemia is similar to that of basophils and mast cells and raises the possibility that the leukaemic cells may have undergone a degree of basophilic differentiation.

The causes of eosinophilia fall into three categories (reactive disorders, clonal disorders of the bone marrow, and hypereosinophilic syndrome). This article outlines the appropriate use of investigations to establish the cause of eosinophilia

A non-radioactive in situ hybridization method has been established for the detection of mRNA for the constant region of light chain immunoglobulin genes in routinely processed bone marrow trephines. The method utilizes a cocktail of biotinylated synthetic oligonucleotide probes to kappa or lambda mRNA. The method entails dewaxing of the paraffin-embedded sections, proteinase K treatment and overnight hybridization with the biotinylated probe. Detection of probe hybridization was performed by 2 immunocytochemical detection methods, utilizing either streptavidin-alkaline phosphatase or monoclonal anti-biotin followed by the alkaline phosphatase: anti-alkaline phosphatase (APAAP) labelling system. The new fuchsin/naphthol phosphate substrate yielded the strongest signal with specific localization of the hybridization signal to positive cells. Morphological preservation was excellent enabling both polyclonal and monoclonal plasma cells to be detected in bone marrow trephines. We conclude that this in situ hybridization method is no more difficult than standard immunohistochemical techniques and can be used in routine diagnostic laboratories.

The JAK2 V617F mutation is found in most patients with a myeloproliferative neoplasm and is sufficient to produce a myeloproliferative phenotype in murine retroviral transplantation or transgenic models. However, several lines of evidence suggest that disease phenotype is influenced by the level of mutant JAK2 signaling, and we have therefore generated a conditional knock-in mouse in which a human JAK2 V617F is expressed under the control of the mouse Jak2 locus. Human and murine Jak2 transcripts are expressed at similar levels, and mice develop modest increases in hemoglobin and platelet levels reminiscent of human JAK2 V617F–positive essential thrombocythemia. The phenotype is transplantable and accompanied by increased terminal erythroid and megakaryocyte differentiation together with increased numbers of clonogenic progenitors, including erythropoietin-independent erythroid colonies. Unexpectedly, JAK2V617F mice develop reduced numbers of lineage−Sca-1+c-Kit+ cells, which exhibit increased DNA damage, reduced apoptosis, and reduced cell cycling. Moreover, competitive bone marrow transplantation studies demonstrated impaired hematopoietic stem cell function in JAK2V617F mice. These results suggest that the chronicity of human myeloproliferative neoplasms may reflect a balance between impaired hematopoietic stem cell function and the accumulation of additional mutations.

The number and volume of cells in the blood affect a wide range of disorders including cancer and cardiovascular, metabolic, infectious and immune conditions. We consider here the genetic variation in eight clinically relevant hematological parameters, including hemoglobin levels, red and white blood cell counts and platelet counts and volume. We describe common variants within 22 genetic loci reproducibly associated with these hematological parameters in 13,943 samples from six European population-based studies, including 6 associated with red blood cell parameters, 15 associated with platelet parameters and 1 associated with total white blood cell count. We further identified a long-range haplotype at 12q24 associated with coronary artery disease and myocardial infarction in 9,479 cases and 10,527 controls. We show that this haplotype demonstrates extensive disease pleiotropy, as it contains known risk loci for type 1 diabetes, hypertension and celiac disease and has been spread by a selective sweep specific to European and geographically nearby populations.

Purpose Essential thrombocythemia (ET) manifests substantial interpatient heterogeneity in rates of thrombosis, hemorrhage, and disease transformation. Bone marrow histology reflects underlying disease activity in ET but many morphological features show poor reproducibility. Patients and Methods We evaluated the clinical significance of bone marrow reticulin, a measure previously shown to have relatively high interobserver reliability, in a large, prospectively-studied cohort of ET patients. Results Reticulin grade positively correlated with white blood cell (P = .05) and platelet counts (P = .0001) at diagnosis. Elevated reticulin levels at presentation predicted higher rates of arterial thrombosis (hazard ratio [HR], 1.8; 95% CI, 1.1 to 2.9; P = .01), major hemorrhage (HR, 2.0; 95% CI, 1.0 to 3.9; P = .05), and myelofibrotic transformation (HR, 5.5; 95% CI, 1.7 to 18.4; P = .0007) independently of known risk factors. Higher reticulin levels at diagnosis were associated with greater subsequent falls in hemoglobin levels in patients treated with anagrelide (P < .0001), but not in those receiving hydroxyurea (P = .9). Moreover, serial trephine specimens in patients randomly assigned to anagrelide showed significantly greater increases in reticulin grade compared with those allocated to hydroxyurea (P = .0003), and four patients who developed increased bone marrow reticulin on anagrelide showed regression of fibrosis when switched to hydroxyurea. These data suggest that patients receiving anagrelide therapy should undergo surveillance bone marrow biopsy every 2 to 3 years and that those who show substantially increasing reticulin levels are at risk of myelofibrotic transformation and may benefit from changing therapy before adverse clinical features develop. Conclusion Our results demonstrate that bone marrow reticulin grade at diagnosis represents an independent prognostic marker in ET, reflecting activity and/or duration of disease, with implications for the monitoring of patients receiving anagrelide.

Activating mutations of MPL exon 10 have been described in a minority of patients with idiopathic myelofibrosis (IMF) or essential thrombocythemia (ET), but their prevalence and clinical significance are unclear. Here we demonstrate that MPL mutations outside exon 10 are uncommon in platelet cDNA and identify 4 different exon 10 mutations in granulocyte DNA from a retrospective cohort of 200 patients with ET or IMF. Allele-specific polymerase chain reaction was then used to genotype 776 samples from patients with ET entered into the PT-1 studies. MPL mutations were identified in 8.5% of JAK2 V617F− patients and a single V617F+ patient. Patients carrying the W515K allele had a significantly higher allele burden than did those with the W515L allele, suggesting a functional difference between the 2 variants. Compared with V617F+ ET patients, those with MPL mutations displayed lower hemoglobin and higher platelet levels at diagnosis, higher serum erythropoietin levels, endogenous megakaryocytic but not erythroid colony growth, and reduced bone marrow erythroid and overall cellularity. Compared with V617F− patients, those with MPL mutations were older with reduced bone marrow cellularity but could not be identified as a discrete clinicopathologic subgroup. MPL mutations lacked prognostic significance with respect to thrombosis, major hemorrhage, myelofibrotic transformation or survival.

Aims: To assess the applicability of an automated tissue immunostainer machine for the phenotypic analysis of peripheral blood and bone marrow aspirate smears. Methods: Air-dried smears of peripheral blood and bone marrow from normal individuals and 14 patients with haematological malignancies were stained, following fixation, with a range of antibodies to haemopoietic antigens using both immunoperoxidase and immuno-alkaline phosphatase methods on the Bond-maX (Leica Microsystems) automated immunostaining machine. Results: Automated protocols used for staining formalin-fixed paraffin-embedded tissue could be applied to cell smears, giving high quality staining with excellent cytological detail and antigenic preservation for an extensive antibody panel. Optimal quality (morphological preservation and antigen detection without background staining) was obtained with an alkaline phosphatase method and Fast Red chromogenic substrate. Both cell surface and intracellular (cytoplasmic and nuclear) antigens could be detected and gave the expected reactivity. Conclusions: Automated immunostaining is possible for haematological smears. It generates consistent high quality staining, with the exception of surface immunoglobulin, and is applicable to haematological and, potentially, cytological smears. It provides a practical alternative to flow cytometry and will have particular application when smears are available and there is no suitable sample for flow cytometry.

The role of histopathology in the diagnosis of essential thrombocythemia (ET) is controversial, and there has been little attempt to quantitate interobserver variability. Diagnostic bone marrow trephine biopsy specimens from 370 patients with ET by Polycythemia Vera Study Group (PVSG) criteria were assessed by 3 experienced hematopathologists for 16 different morphologic features and overall diagnosis according to the World Health Organization (WHO) classification. Our results show substantial interobserver variability, particularly for overall diagnosis and individual cellular characteristics such as megakaryocyte morphology. Reticulin grade was the dominant independent predictor of WHO diagnostic category for all 3 hematopathologists. Factor analysis identified 3 independent factors likely to reflect underlying biologic processes. One factor related to overall and lineage-specific cellularity and was significantly associated with JAK2 V617F status (P < .001), a second factor related to megakaryocyte clustering, and a third was associated with the fibrotic process. No differences could be discerned between patients labeled as having “prefibrotic myelofibrosis” or “true ET” in clinical and laboratory features at presentation, JAK2 status, survival, thrombosis, major hemorrhage, or myelofibrotic transformation. These results show that histologic criteria described in the WHO classification are difficult to apply reproducibly and question the validity of distinguishing true ET from prefibrotic myelofibrosis on the basis of subjective morphologic criteria. This study was registered at http://isrctn.org as #72251782 and at http://eudract.emea.europa.eu/ as #2004-000245-38.

Cluster of differentiation (CD) antigens are expressed on cells of myeloid and lymphoid lineages. As most disease processes involve immune system activation or suppression, these antigens offer unique opportunities for monitoring host responses. Immunophenotyping using limited numbers of CD antigens enables differentiation states of immune system cells to be determined. Extended phenotyping involving parallel measurement of multiple CD antigens may help identify expression pattern signatures associated with specific disease states. To explore this possibility we have made a CD monoclonal antibody array and scanner, enabling the parallel immunophenotyping of leukocyte cell suspensions in a single and rapid analysis. To demonstrate this approach, we used the specific example of patients infected with human immunodeficiency virus type-1 (HIV-1). An invariant HIV-induced CD antigen signature has been defined that is both robust and independent of clinical outcome, composed of a unique profile of CD antigen expression levels that are both increased and decreased relative to internal controls. The results indicate that HIV-induced changes in CD antigen expression are disease specific and independent of outcome. Their invariant nature indicates an irreversible component to retroviral infection and suggests the utility of CD antigen expression patterns in other disease settings.

In vitro studies have implicated the Lyn tyrosine kinase in erythropoietin signaling. In this study, we show that J2E erythroid cells lacking Lyn have impaired signaling and reduced levels of transcription factors STAT5a, EKLF and GATA-1. Since mice lacking STAT5, EKLF or GATA-1 have red cell abnormalities, this study also examined the erythroid compartment of Lyn(-/-) mice. Significantly, STAT5, EKLF and GATA-1 levels were appreciably lower in Lyn(-/-) erythroblasts, and the phenotype of Lyn(-/-) animals was remarkably similar to GATA-1(low) animals. Although young adult Lyn-deficient mice had normal hematocrits, older mice developed anemia. Grossly enlarged erythroblasts and florid erythrophagocytosis were detected in the bone marrow of mice lacking Lyn. Markedly elevated erythroid progenitors and precursor levels were observed in the spleens, but not bone marrow, of Lyn(-/-) animals indicating that extramedullary erythropoiesis was occurring. These data indicate that Lyn(-/-) mice display extramedullary stress erythropoiesis to compensate for intrinsic and extrinsic erythroid defects.