2021 Update on MRD in acute myeloid leukemia: a consensus document from the European LeukemiaNet MRD Working Party.

Measurable residual disease (MRD) is an important biomarker in acute myeloid leukemia (AML) that is used for prognostic, predictive, monitoring, and efficacy-response assessments. The European LeukemiaNet (ELN) MRD Working Party evaluated standardization and harmonization of MRD in an ongoing manner and has updated the 2018 ELN MRD recommendations based on significant developments in the field. New and revised recommendations were established during in-person and online meetings, and a 2-stage Delphi poll was conducted to optimize consensus. All recommendations are graded by levels of evidence and agreement. Major changes include technical specifications for next-generation sequencing-based MRD testing and integrative assessments of MRD irrespective of technology. Other topics include use of MRD as a prognostic and surrogate end point for drug testing; selection of the technique, material, and appropriate time points for MRD assessment; and clinical implications of MRD assessment. In addition to technical recommendations for flow- and molecular-MRD analysis, we provide MRD thresholds and define MRD response, and detail how MRD results should be reported and combined if several techniques are used. MRD assessment in AML is complex and clinically relevant, and standardized approaches to application, interpretation, technical conduct, and reporting are of critical importance.

Psychosocial wellbeing among children and adults with arthrogryposis: a scoping review.

BACKGROUND: Arthrogryposis multiplex congenita (AMC) is a group of congenital conditions characterized by joint contractures in two or more body areas. Management of AMC starts early in life and focuses on improving mobility and function through intensive rehabilitation and surgical interventions. Psychosocial wellbeing is an important determinant of health and the psychosocial experience of individuals with AMC should be considered in the management of this condition. The aim of this scoping review was to explore what is known about the psychosocial wellbeing of children and adults with AMC, to identify the outcome measures used and to explore the factors associated with psychosocial outcomes in this population. METHODS: A comprehensive search in four databases was conducted. Articles discussing psychosocial outcomes and outcome measures used with children or adults with AMC were included. Data on the measures used, psychosocial outcomes, and factors associated with psychosocial outcomes, were extracted and analyzed descriptively and synthesized narratively. RESULTS: Seventeen articles were included in this scoping review, ten including the pediatric population, six including adults and one article including both children and adults with AMC. The most commonly used outcome measures were the PODCI in the pediatric studies, and the SF-36 in studies on adults. In the pediatric studies, psychosocial outcomes were often secondary, compared to the studies on adults. Results showed that in both children and adults, psychosocial outcomes are comparable with the levels of the general population. Qualitative studies reflected the affective needs of this population and issues with emotional wellbeing. Factors such as fatigue and pain were associated with poorer psychosocial outcomes in adults with an impact on social relationships, intimacy and family planning. CONCLUSION: Validated outcome measures, qualitative approaches and longitudinal studies are needed to better understand the psychosocial outcomes in AMC over time. Psychosocial support should be part of the multidisciplinary management of AMC throughout the lifespan.

Minimal/measurable residual disease in AML: a consensus document from the European LeukemiaNet MRD Working Party.

Measurable residual disease (MRD; previously termed minimal residual disease) is an independent, postdiagnosis, prognostic indicator in acute myeloid leukemia (AML) that is important for risk stratification and treatment planning, in conjunction with other well-established clinical, cytogenetic, and molecular data assessed at diagnosis. MRD can be evaluated using a variety of multiparameter flow cytometry and molecular protocols, but, to date, these approaches have not been qualitatively or quantitatively standardized, making their use in clinical practice challenging. The objective of this work was to identify key clinical and scientific issues in the measurement and application of MRD in AML, to achieve consensus on these issues, and to provide guidelines for the current and future use of MRD in clinical practice. The work was accomplished over 2 years, during 4 meetings by a specially designated MRD Working Party of the European LeukemiaNet. The group included 24 faculty with expertise in AML hematopathology, molecular diagnostics, clinical trials, and clinical medicine, from 19 institutions in Europe and the United States.

An R-Derived FlowSOM Process to Analyze Unsupervised Clustering of Normal and Malignant Human Bone Marrow Classical Flow Cytometry Data.

Multiparameter flow cytometry (MFC) is a powerful and versatile tool to accurately analyze cell subsets, notably to explore normal and pathological hematopoiesis. Yet, mostly supervised subjective strategies are used to identify cell subsets in this complex tissue. In the past few years, the implementation of mass cytometry and the big data generated have led to a blossoming of new software solutions. Their application to classical MFC in hematology is however still seldom reported. Here, we show how one of these new tools, the FlowSOM R solution, can be applied, together with the Kaluza® software, to a new delineation of hematopoietic subsets in normal human bone marrow (BM). We thus combined the unsupervised discrimination of cell subsets provided by FlowSOM and their expert-driven node-by-node assignment to known or new hematopoietic subsets. We also show how this new tool could modify the MFC exploration of hematological malignancies both at diagnosis (Dg) and follow-up (FU). This can be achieved by direct comparison of merged listmodes of reference normal BM, Dg, and FU samples of a representative acute myeloblastic case tested with the same immunophenotyping panel. This provides an immediate unsupervised evaluation of minimal residual disease. © 2019 International Society for Advancement of Cytometry.

Prognostic value of multicenter flow cytometry harmonized assessment of minimal residual disease in acute myeloblastic leukemia.

The assessment of minimal residual disease (MRD) in acute myeloblastic leukemia is of growing interest as a prognostic marker of patients' outcome. Multiparameter flow cytometry (MFC), tracking leukemia-associated immunophenotypic patterns, has been shown in several studies to be a useful tool to investigate MRD. Here, we report a multicenter prospective study which allowed to define a harmonized analysis strategy, as well as the efficacy of MFC MRD to predict outcome. This study included 276 patients, in 10 different MFC centers, of whom 268 had at least 1 MRD check point. The combination of a CD45, CD34, and CD33 backbone, with the addition of CD117, CD13, CD7, and CD15 in 2 five-color tubes allowed to define each patient's multiparameter immunophenotypic characteristics at diagnosis, according to a Boolean combination of gates. The same individual diagnosis gating strategy was then applied at each MRD time point for each patient. MRD levels were stratified according to log by log thresholds, from 5 × 10-2 (the classical morphological threshold to define remission) down to <5 × 10-5 . MRD was found to be constantly negative (<5 × 10-5 ) for 148 patients. Survival analyses significantly associated MRD negativity with a good prognosis and any positive value with poorer outcome. All P values were <0.0001 both for disease-free and overall survival at the earliest time point (post-induction, MRD1) as well as when considering all time points together. Finally, MRD levels were independent of cytogenetics and allowed in fact to further stratify all cytogenetics risk groups. In summary, this multicenter study demonstrates that a simple combination of immunophenotypic markers successfully allows for the detection of MRD in acute myeloblastic leukemia patients, with a strong correlation to outcome.

Circulating immature granulocytes with T-cell killing functions predict sepsis deterioration*.

OBJECTIVES: Primary objective was to identify leukocyte subsets that could predict the early evolution of sepsis at 48 hours (i.e., deterioration or stability/improvement). Secondary objectives were to evaluate the prognostic value of leukocyte subsets on mortality and immunosuppressive properties of immature granulocytes. DESIGN: Twenty-three peripheral blood leukocyte subsets were analyzed using a new-generation 10-color flow cytometry. T-cell killing activity of immature granulocytes was explored using a sorting method specifically developed. SETTING: ICUs and emergency departments. PATIENTS: All patients admitted to emergency department and ICU for sepsis ongoing for less than 24 hours were eligible. Exclusion criteria were pregnancy, age less than 18 years, solid tumors, HIV infection, hematological or inflammatory conditions, and immunosuppressive drugs. Finally, 177 patients were included. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The two most salient features of sepsis were decreased CD10 (CD10) and CD16 (CD16) expressions on granulocytes. With a threshold of 90% of CD10 and 15% of CD16 granulocytes, these immunophenotypic features, which are those of immature granulocytes, predicted sepsis deterioration at 48 hours with a sensitivity of 57% and 70% and a specificity of 78% and 82%, respectively. Survival rate at day 30 was 99% for patients without CD10 and CD16, 85% for patients with increased CD16 only, and 63% for patients with increased CD16 and CD10 granulocytes (p < 0.001). Among CD16 immature granulocytes, we identified a CD14/CD24 myeloid-derived suppressor cell subset with the capability of killing activated T cells. Consistently, an excess of CD16 immature granulocytes was associated with both CD3 and CD4 T-cell lymphopenia in deteriorating patients. CONCLUSIONS: Circulating immature granulocytes predicted early sepsis deterioration and were enriched in myeloid-derived suppressor cells which could be responsible for immunosuppression through the induction of T-cell lymphopenia.

Flow cytometry thresholds of myeloperoxidase detection to discriminate between acute lymphoblastic or myeloblastic leukaemia.

The World Health Organization 2008 Classification emphasizes myeloperoxidase (MPO) detection as sufficient for assigning a blast population to the myeloid lineage. Published MPO positivity thresholds are 10% for flow cytometry (FCM) but 3% for cytochemistry. Here we re-evaluated the FCM-MPO threshold by comparing retrospectively 128 acute lymphoblastic leukaemias and 75 acute myeloid leukaemias without maturation, all assessed by benzidine-based cytochemistry. A 13% threshold was found to be relevant using an isotype control as background-reference (sensitivity 95·1%, specificity 91·7%). Residual normal lymphocytes proved to be an advantageous alternative reference, a threshold of 28% yielding improved 97·4% sensitivity and 96·1% specificity.

Comparable flow cytometry data can be obtained with two types of instruments, Canto II, and Navios. A GEIL study.

Flow cytometry (FC) instruments settings classically rely on local establishment of photomultipliers (PMT) voltages adapted to the measurements expected to be performed. In the era of multiparameter FC (MFC), it appears more and more desirable that comparable patterns of fluorescence are obtained in different settings. This relies on a harmonization of settings between instruments. Although this has been shown to be feasible within a given brand of flow cytometers, little information is available about broader comparisons in a given center or in a multicenter fashion. Here, we report a two-phase series of experiments first performed between a Canto II (BD Biosciences) and a Navios (Beckman Coulter) instruments in the same center. PMT values adjusted on the reference instrument (RI) Canto II were used to establish target values for PMT settings on the paired Navios practice instrument (PI). This allowed to show the good correlation of all but peaks 1 and 2 of Rainbow(®) beads between RI and PI. Using 4- or 8-color stained leukocytes, the similitude of the settings was further confirmed. A complex set of matrices was then established between five centers all equipped with both instruments. Using Bland & Altman difference comparisons for median fluorescence values, it was shown that using either Rainbow beads or CD16 stained polymorphonuclears to set-up target values on the RI CantoII, highly superimposable results could be obtained on all 9 PI. The latter were obtained using Rainbow beads or Compbeads(®) for comparisons. In summary, this two-phase study demonstrates the feasibility of different methods allowing for a robust harmonization of settings for MFC.

Current rehabilitation practice for the evaluation and treatment of children with arthrogryposis: an international survey.

PURPOSE: To describe the current practices in rehabilitation for the evaluation and treatment of children with arthrogryposis multiplex congenita (AMC). MATERIALS AND METHODS: Rehabilitation practitioners worldwide with at least 2 years of experience with AMC were invited to complete an electronic survey on the evaluations and treatments used with children with AMC within five areas: muscle and joint function, self-care, mobility, pain, participation and psychosocial wellbeing. RESULTS: Sixty five participants from nine countries completed the survey. Participants completed the sections applicable to their practice. Number of participants within each area varied between 24 and 53. Over 80% of participants used non-standardized evaluations across areas while <50% used patient-reported or standardized measures. Stretching of upper and lower limbs was reported by >80% across ages and clinical presentation severity. Strengthening reported by >70% was mainly used among children >3 years old with less severe contractures. Other interventions used across areas included orthotics (>70%), positioning (>80%), activity-based training (>80%), assistive devices for self-care (>50%) and mobility (>80%), and energy conservation (>70%). Over 70% of participants were involved in perioperative rehabilitation. CONCLUSION: Knowledge of current pediatric rehabilitation practice in AMC, together with empirical evidence, may guide clinical decision-making and identify avenues for future research.

Arthrogryposis multiplex congenita (AMC) is a group of rare conditions and there is currently little empirical evidence on rehabilitation, therefore expert opinion is important to guide best practice.Rehabilitation practitioners should consider the areas of muscle and joint function, self-care and mobility, pain, participation, and psychosocial wellbeing when evaluating and developing a treatment plan for children with AMC.Considering the heterogeneity of AMC, different assessment tools may be selected depending on the clinical presentation of each child.In addition to stretching, orthotic use, and strengthening, the use of activity based training and assistive equipment is important to promote self-care, mobility and participation.

Unsupervised cluster analysis and subset characterization of abnormal erythropoiesis using the bioinformatic Flow-Self Organizing Maps algorithm.

BACKGROUND: The Flow-Self Organizing Maps (FlowSOM) artificial intelligence (AI) program, available within the Bioconductor open-source R-project, allows for an unsupervised visualization and interpretation of multiparameter flow cytometry (MFC) data. METHODS: Applied to a reference merged file from 11 normal bone marrows (BM) analyzed with an MFC panel targeting erythropoiesis, FlowSOM allowed to identify six subpopulations of erythropoietic precursors (EPs). In order to find out how this program would help in the characterization of abnormalities in erythropoiesis, MFC data from list-mode files of 16 patients (5 with non-clonal anemia and 11 with myelodysplastic syndrome [MDS] at diagnosis) were analyzed. RESULTS: Unsupervised FlowSOM analysis identified 18 additional subsets of EPs not present in the merged normal BM samples. Most of them involved subtle unexpected and previously unreported modifications in CD36 and/or CD71 antigen expression and in side scatter characteristics. Three patterns were observed in MDS patient samples: i) EPs with decreased proliferation and abnormal proliferating precursors, ii) EPs with a normal proliferating fraction and maturation defects in late precursors, and iii) EPs with a reduced erythropoietic fraction but mostly normal patterns suggesting that erythropoiesis was less affected. Additionally, analysis of sequential samples from an MDS patient under treatment showed a decrease of abnormal subsets after azacytidine treatment and near normalization after allogeneic hematopoietic stem-cell transplantation. CONCLUSION: Unsupervised clustering analysis of MFC data discloses subtle alterations in erythropoiesis not detectable by cytology nor FCM supervised analysis. This novel AI analytical approach sheds some new light on the pathophysiology of these conditions.

Expert guidance for the rehabilitation of children with arthrogryposis: protocol using an integrated knowledge translation approach.

BACKGROUND: Arthrogryposis multiplex congenita (AMC) is a group of rare congenital disorders characterized by multiple joint contractures present at birth. Contractures can affect different body areas and impact activities of daily living, mobility and participation. Although early rehabilitation is crucial to promote autonomy and participation in children with AMC, empirical evidence to inform best practice is scarce and clinical expertise hard to develop due to the rarity of AMC. Preliminary research involving stakeholders in AMC (youth with AMC, parents, and clinicians) identified priorities in pediatric rehabilitation. Scoping reviews on these priorities showed a lack of high quality evidence related to rehabilitation in AMC. The objective of this project is to provide rehabilitation expert guidance on the assessment and treatment of children with AMC in the areas of muscle and joint function, pain, mobility and self-care, participation and psychosocial wellbeing. METHODS: An integrated knowledge translation approach will be used throughout the project. Current rehabilitation practices in AMC will be identified using a clinician survey. Using the Grading of Recommendations, Assessment, Development and Evaluations framework (GRADE) approach, a panel of interdisciplinary expert clinicians, patient and family representatives, and researchers will develop expert guidance on the assessment and treatment for pediatric AMC rehabilitation based on findings from the scoping reviews and survey results. Consensus on the guidance statements will be sought using a modified Delphi process with a wider panel of international AMC experts, and statements appraised using the Appraisal of Guidelines for Research and Evaluation II (AGREE II) tool. Theoretical facilitators and barriers toward implementing clinical guidance into practice will be identified among rehabilitation clinicians and managers to inform the design of dissemination and implementation strategies. DISCUSSION: This multi-phase project will provide healthcare users and providers with research-based, expert guidance for the rehabilitation of children with AMC and will contribute to family-centered practice.

Arthrogryposis multiplex congenita (AMC) is a group of rare disorders where a child is born with stiff joints. Joint stiffness can be present in different parts of the body, making it difficult for the child to move, to walk and to participate in activities. Rehabilitation interventions starting early in life are very important to maximize autonomy. AMC being rare, it is difficult for clinicians to develop experience with this population and there is little research specific to rehabilitation interventions in AMC. In a previous research project, a group of youth with AMC and their families identified five areas of priority for rehabilitation: muscle and joint function, pain, mobility and self-care, participation and psychosocial wellbeing. The purpose of this project is to provide guidance for the evaluation and treatment of children with AMC, in these priority areas. The project involves multiple steps. First, we will perform an online survey with international rehabilitation practitioners to learn about current evaluation and treatment approaches used with children with AMC. We will then bring together expert clinicians, patient and family representatives, and researchers to develop the guidance statements. Then, we will perform an online survey with a larger group of international experts to validate and finalize the guidance statements. Finally, we will interview rehabilitation clinicians and managers to find out about what could help them or limit them in integrating this guidance into their practice. This project will provide healthcare users and providers with research and expert-based guidance for the rehabilitation of children with AMC.

Technical Aspects of Flow Cytometry-based Measurable Residual Disease Quantification in Acute Myeloid Leukemia: Experience of the European LeukemiaNet MRD Working Party.

Measurable residual disease (MRD) quantified by multiparameter flow cytometry (MFC) is a strong and independent prognostic factor in acute myeloid leukemia (AML). However, several technical factors may affect the final read-out of the assay. Experts from the MRD Working Party of the European LeukemiaNet evaluated which aspects are crucial for accurate MFC-MRD measurement. Here, we report on the agreement, obtained via a combination of a cross-sectional questionnaire, live discussions, and a Delphi poll. The recommendations consist of several key issues from bone marrow sampling to final laboratory reporting to ensure quality and reproducibility of results. Furthermore, the experiences were tested by comparing two 8-color MRD panels in multiple laboratories. The results presented here underscore the feasibility and the utility of a harmonized theoretical and practical MFC-MRD assessment and are a next step toward further harmonization.

Unsupervised flow cytometry analysis in hematological malignancies: A new paradigm.

Ever since hematopoietic cells became "events" enumerated and characterized in suspension by cell counters or flow cytometers, researchers and engineers have strived to refine the acquisition and display of the electronic signals generated. A large array of solutions was then developed to identify at best the numerous cell subsets that can be delineated, notably among hematopoietic cells. As instruments became more and more stable and robust, the focus moved to analytic software. Almost concomitantly, the capacity increased to use large panels (both with mass and classical cytometry) and to apply artificial intelligence/machine learning for their analysis. The combination of these concepts raised new analytical possibilities, opening an unprecedented field of subtle exploration for many conditions, including hematopoiesis and hematological disorders. In this review, the general concepts and progress achieved in the development of new analytical approaches for exploring high-dimensional data sets at the single-cell level will be described as they appeared over the past few years. A larger and more practical part will detail the various steps that need to be mastered, both in data acquisition and in the preanalytical check of data files. Finally, a step-by-step explanation of the solution in development to combine the Bioconductor clustering algorithm FlowSOM and the popular and widely used software Kaluza® (Beckman Coulter) will be presented. The aim of this review was to point out that the day when these progresses will reach routine hematology laboratories does not seem so far away.

Unsupervised Flow Cytometry Analysis Allows for an Accurate Identification of Minimal Residual Disease Assessment in Acute Myeloid Leukemia.

The assessment of minimal residual disease (MRD) is increasingly considered to monitor response to therapy in hematological malignancies. In acute myeloblastic leukemia (AML), molecular MRD (mMRD) is possible for about half the patients while multiparameter flow cytometry (MFC) is more broadly available. However, MFC analysis strategies are highly operator-dependent. Recently, new tools have been designed for unsupervised MFC analysis, segregating cell-clusters with the same immunophenotypic characteristics. Here, the Flow-Self-Organizing-Maps (FlowSOM) tool was applied to assess MFC-MRD in 96 bone marrow (BM) follow-up (FU) time-points from 40 AML patients with available mMRD. A reference FlowSOM display was built from 19 healthy/normal BM samples (NBM), then simultaneously compared to the patient's diagnosis and FU samples at each time-point. MRD clusters were characterized individually in terms of cell numbers and immunophenotype. This strategy disclosed subclones with varying immunophenotype within single diagnosis and FU samples including populations absent from NBM. Detectable MRD was as low as 0.09% in MFC and 0.051% for mMRD. The concordance between mMRD and MFC-MRD was 80.2%. MFC yielded 85% specificity and 69% sensitivity compared to mMRD. Unsupervised MFC is shown here to allow for an easy and robust assessment of MRD, applicable also to AML patients without molecular markers.

Adverse prognostic significance of CD20 expression in adults with Philadelphia chromosome-negative B-cell precursor acute lymphoblastic leukemia.

The prognostic significance of CD20 expression in B-cell precursor acute lymphoblastic leukemia (BCP-ALL) has been mostly studied in children and yielded conflicting results. In 143 adults with Philadelphia chromosome-negative BCP-ALL treated in the multicentric GRAALL 2003 trial, CD20 positivity over 20% was observed in 32% of patients. While not influencing complete remission achievement, CD20 expression was associated with a higher cumulative incidence of relapse (CIR) at 42 months (P=0.04), independently of the ALL high-risk subset (P=0.025). Notably, the negative impact of CD20 expression on CIR was only observed in patients with a white blood cell count (WBC) over 30x10(9)/L (P=0.006), while not in those with a lower WBC. In the former subgroup, this impact translated into lower event-free survival (15% vs. 59% at 42 months, P=0.003). CD20 expression thus appears to be associated with a worse outcome, which reinforces the interest of evaluating rituximab combined to chemotherapy in CD20-positive adult BCP-ALL. ClinicalTrials.gov ID, NCT00222027.

Obtaining of CD34+ cells from healthy blood donors: development of a rapid and efficient procedure using leukoreduction filters.

BACKGROUND: Human CD34+ cells are mandatory to study many aspects of human hematopoiesis. Their low frequency in blood or marrow and ethical reasons limit their obtainment in large quantities. Leukoreduction filters (LRFs) are discarded after preparation of red blood cells. The CD34+ cell concentration in healthy donor blood is low (1×10(3) -4×10(3) /mL), but their number trapped in one LRF after filtration of 400 to 450mL of blood is high (0.4×10(6) -1.6×10(6) ). STUDY DESIGN AND METHODS: To develop a procedure allowing obtainment of purified CD34+ cells from LRFs with a good yield, white blood cell (WBC) recoveries after a 500-mL continuous or after sequential elution (50- or 20-mL fractions) were compared. Different WBC and mononuclear cell (MNC) centrifugation methods were tested to minimize their PLT contamination before the CD34+ cell immunomagnetic selection. Cell functionality was finally analyzed under various culture conditions. RESULTS: The 20-mL back-flushing of LRFs allowed the most efficient WBC recovery. The next steps (110×g centrifugation, MNC separation on Ficoll, and washes) resulted in a cell suspension in which the lymphocyte recovery was approximately 76±10% and the PLT contamination below 1.6%. After immunomagnetic selection, 4×10(5) to 6×10(5) cells containing approximately 85% of functional CD34+ cells were obtained. CONCLUSION: This procedure allows the easy, rapid (<5hr), and efficient preparation of large quantities of CD34+ cells having functional activities similar to those of CD34+ cells from other sources. Therefore, easily available and virally safe, LRFs represent an important and regular WBC source to work with human CD34+ cells, but also with other WBC types.

Triptolide cooperates with chemotherapy to induce apoptosis in acute myeloid leukemia cells.

OBJECTIVE: Triptolide has shown antitumor activity in a broad range of solid tumors and on leukemic cells in vitro. MATERIALS AND METHODS: The THP1 cell line and primary acute myeloid leukemia (AML) cells were cultured with triptolide alone or in association with AraC or idarubicin in increasing concentrations. Apoptosis was measured by flow cytometry using DiOC6(3) for the cell line and fluorescein isothiocyanateAnnexin-V and CD45 labeling for fresh blast cells. Protein expression was measured by Western blot. Cell cycle distribution of apoptotic cells was measured by flow cytometry. RESULTS: A synergistic effect was observed when triptolide was added to idarubicin or to AraC to induce apoptosis of THP-1 leukemic cells. The triptolide/AraC association was also investigated in vitro on primary blast cells from 25 AML patients. This combination induced significantly higher percentages of apoptosis vs treatment with each drug separately (p<0.005). The IkappaB and X-linked inhibitor of apoptosis protein contents, which were altered by triptolide in idarubicin-treated cells, were not modified in AraC-treated cells. The association of AraC with triptolide increased the number of cells blocked in the S phase and most underwent apoptosis. CONCLUSION: These results suggest that, by modifying the cell cycle kinetics, AraC sensitizes AML cells to apoptosis induced by low concentration triptolide. The in vitro proapoptotic effect of triptolide associated with the antiproliferative activity of AraC warrants further clinical investigation for treatment of AML patients, especially elderly patients for whom low-dose AraC treatment could be improved by the addition of triptolide.

Reference Values for WBC Differential by Hematoflow Analysis.

Objectives: WBC differentials performed using flow cytometry with monoclonal antibodies have been developed in the last decade and are nowadays integrated into the routine workflow of some laboratories. Definition of reference values for each population is required in order to achieve an automatic validation of the results by laboratory software. Methods: We analyzed 584 samples from three hospitals using the Hematoflow solution to define the reference values. Results: Reference values are presented for five groups according to age (0-5, 6-11, 12-19, 20-69, and >69 years). Conclusions: These normal values will be helpful in the definition of relevant threshold for the automatic validation of samples analyzed by flow cytometry and the flagging of pathologic samples.

Gravitational stress during parabolic flights reduces the number of circulating innate and adaptive leukocyte subsets in human blood.

Gravitational stress occurs during space flights or certain physical activities including extreme sports, where the change in experienced gravitational acceleration can reach large magnitudes. These changes include reduction and increase in the physical forces experienced by the body and may potentially induce pathogenic alterations of physiological processes. The immune system is known to regulate most functions in the human organism and previous studies suggest an impairment of the immune function under gravitational stress. However, systematic studies aiming to investigate the effect of gravitational stress on cellular immune response in humans are lacking. Since parabolic flights are considered as feasible model to investigate a short-term impact of gravitational changes, we evaluated the influence of gravitational stress on the immune system by analyzing leukocyte numbers before and after parabolic flight maneuvers in human blood. To correct for circadian effects, samples were taken at the corresponding time points on ground the day before the flight. The parabolic flight maneuvers led to changes in numbers of different leukocyte subsets. Naïve and memory T and B cell subsets decreased under gravitational stress and lower numbers of basophils and eosinophils were observed. Only circulating neutrophils increased during the parabolic flight. The observed changes could not be attributed to stress-induced cortisol effects, since cortisol levels were not affected. Our data demonstrate that the gravitational stress by parabolic flights can affect all parts of the human immune system. Consequently, it is possible that gravitational stress can have clinically relevant impacts on the control of immune responses.

Proteasome inhibition specifically sensitizes leukemic cells to anthracyclin-induced apoptosis through the accumulation of Bim and Bax pro-apoptotic proteins.

Proteasome inhibitors are a novel class of compounds that might increase sensitivity to chemotherapy for acute myeloid leukemia (AML). We quantified apoptosis in THP-1 cells incubated with idarubicin (IDA) alone or together with a low concentration of MG132 or bortezomib. The combination of both drugs yielded a percentage of apoptotic cells that was significantly higher than the additive effect of both drugs administered separately (p < 0.01). Isobologram analysis showed that both MG132 and bortezomib interacted synergistically with IDA to induce apoptosis of THP1 cells. Western blot analysis of Bax and Bim show an acumulation of these pro-apoptotic proteins in THP1 treated cells. This increase in Bim preceded the induction of apoptosis and participated in idarubicin-induced apoptosis. Proteasome inhibition also potentiated IDA-induced apoptosis in primary blast cells from 22 AML patients while no such effect was found on normal lymphocytes, PHA-stimulated lymphocytes, normal cord blood CD34+ cells or bone marrow normal myeloid cells. These data show that MG132 and bortezomib specifically sensitize leukemic cells to IDA through an increase in BIM and Bax pro-apoptotic Bcl-2 family proteins.