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Minimal residual disease (MRD) monitoring plays a pivotal role in the management of hematologic malignancies. Well-established molecular targets, such as PML::RARA, CBFB::MYH11, or RUNX1::RUNX1T1, are conventionally tracked by quantitative RT-PCR. Recently, a broader landscape of fusion transcripts has been unveiled through transcriptomic analysis. These newly discovered fusion transcripts may emerge as novel molecular markers for MRD quantification. In this study, we compared a targeted RNA-sequencing (RNA-seq) approach (FusionPlex) with a whole-transcriptomic strategy (Advanta RNA-Seq XT) for fusion detection in a training set of 21 samples. We evidenced a concordance of 100% for the detection of known fusions, and showed a good correlation for gene expression quantification between the two techniques (Spearman r = 0.77). Additionally, we prospectively evaluated the identification of fusions by targeted RNA-seq in a real-life series of 126 patients with hematological malignancy. At least one fusion transcript was detected for 60 patients (48%). We designed tailored digital PCR assays for 11 rare fusions, and validated this technique for MRD quantification with a limit of detection of <0.01%. The combination of RNA-seq and tailored digital PCR may become a new standard for MRD evaluation in patients lacking conventional molecular targets., Competing Interests: Disclosure Statement None declared., (Copyright © 2024 Association for Molecular Pathology and American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Background: VEXAS (Vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome is caused by acquired somatic mutations in UBA1. Sweet-syndrome-like skin disorders [and especially histiocytoid Sweet syndrome (HSS)] may be associated with VEXAS syndrome., Objectives: To characterize the clinical and histopathological features of HSS in patients with VEXAS syndrome., Methods: Skin biopsies with a histological diagnosis of HSS at Rennes University Medical Center (Rennes, France) between October 2011 and January 2022 were reviewed in this study. Sanger sequencing and digital polymerase chain reaction were used to screen skin, blood and bone marrow samples for UBA1 variants, and thus classify patients as having VEXAS syndrome or not. We evaluated the clinical, histological and molecular (UBA1) characteristics of patients with or without VEXAS syndrome., Results: We compared 15 skin biopsies from 7 patients found to have VEXAS syndrome and 19 skin biopsies from 15 patients without VEXAS syndrome. Persistent C-reactive protein elevation, macrocytosis, anaemia and haematological malignancies were more prevalent in patients with VEXAS syndrome [6/7 (86%), 6/7 (86%), 7/7 (100%) and 6/7 (86%), respectively] than in patients without [5/14 (36%), 6/15 (40%), 8/15 (53%) and 8/15 (53%), respectively]. These features sometimes appeared after the first skin manifestations, and a UBA1 mutation was found in the skin of five patients with VEXAS syndrome. Dermal infiltration by reniform histiocytoid cells (myeloperoxidase-positive and/or CD163-positive) and a periadnexal distribution were more frequently observed in VEXAS syndrome biopsies [15/15 (100%) and 3/15 (20%), respectively, vs. 11/19 (58%) and 0/19 (0%) in non-VEXAS syndrome biopsies, respectively]., Conclusions: Our findings might help pathologists to consider a diagnosis of VEXAS syndrome and to initiate early genetic testing., Competing Interests: Conflicts of interest The authors declare no conflicts of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of British Association of Dermatologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Large granular lymphocytic (LGL) leukaemia is a rare chronic lymphoproliferative disorder characterized by an expansion of cytotoxic T or NK cells. Despite a usually indolent evolution, most patients will require a treatment over the course of the disease because of cytopenia or symptomatic associated autoimmune disorders. First-line treatment is based on immunosuppressive agents, namely cyclophosphamide, methotrexate and ciclosporin. However, relapses are frequent, and there is no consensus on the management of relapsed/refractory patients. The implication of the JAK/STAT pathway in the pathogenesis of this disease has prompted our group to propose treatment with ruxolitinib. A series of 21 patients who received this regimen is reported here. Ten patients (47.6%) were refractory to the three main immunosuppressive drugs at the time of ruxolitinib initiation. Ruxolitinib yielded an overall response rate of 86% (n = 18/21), including 3 complete responses and 15 partial responses. With a median follow-up of 9 months, the median response duration was 4 months. One-year event-free survival and 1-year overall survival were 57% and 83% respectively. Mild side effects were observed. Biological parameters, notably neutropenia and anaemia, improved significantly, and complete molecular responses were evidenced. This study supports ruxolitinib as a valid option for the treatment of relapsed/refractory LGL leukaemia., (© 2024 The Authors. British Journal of Haematology published by British Society for Haematology and John Wiley & Sons Ltd.)

KMT2A-rearranged (KMT2A-r) B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is widely recognized as a high-risk leukemia in both children and adults. However, there is a paucity of data on adults treated in recent protocols, and the optimal treatment strategy for these patients is still a matter of debate. In this study, we set out to refine the prognosis of adult KMT2A-r BCP-ALL treated with modern chemotherapy regimen and investigate the prognostic impact of comutations and minimal residual disease (MRD). Of 1091 adult patients with Philadelphia-negative BCP-ALL enrolled in 3 consecutive trials from the Group for Research on Adult Acute Lymphoblastic Leukemia (GRAALL), 141 (12.9%) had KMT2A-r, with 5-year cumulative incidence of relapse (CIR) and overall survival (OS) rates of 40.7% and 53.3%, respectively. Molecular profiling highlighted a low mutational burden in this subtype, reminiscent of infant BCP-ALL. However, the presence of TP53 and/or IKZF1 alterations defined a subset of patients with significantly poorer CIR (69.3% vs 36.2%; P = .001) and OS (28.1% vs 60.7%; P = .006) rates. Next, we analyzed the prognostic implication of MRD measured after induction and first consolidation, using both immunoglobulin (IG) or T-cell receptor (TR) gene rearrangements and KMT2A genomic fusion as markers. In approximately one-third of patients, IG/TR rearrangements were absent or displayed clonal evolution during the disease course, compromising MRD monitoring. In contrast, KMT2A-based MRD was highly reliable and strongly associated with outcome, with early good responders having an excellent outcome (3-year CIR, 7.1%; OS, 92.9%). Altogether, our study reveals striking heterogeneity in outcomes within adults with KMT2A-r BCP-ALL and provides new biomarkers to guide risk-based therapeutic stratification., (© 2023 by The American Society of Hematology.)

Introduction: Factor X deficiency is a rare inherited bleeding disorder. To date, 181 variants are reported in the recently updated F10-gene variant database., Aim: This study aimed to describe new F10 variants., Method: The F10 gene was analysed in 16 consecutive families with FX deficiency by a targeted high-throughput sequencing approach, including F10, F9, F8 genes, and 78 genes dedicated to haematological malignancies., Results: We identified 19 variants (17 missense, one nonsense and one frameshift) and two copy number variations. Two patients presenting a combined FVII-FX deficiency showed a loss of one F10 gene copy (del13q34) associated with a missense variant on the remaining allele, leading to a FX:C significantly lower than the FVII:C level and explaining their unusual bleeding history. We reported five novel variants. Three missense variants (p.Glu22Val affecting the signal peptide cleavage site, p.Cys342Tyr removing the disulphide bond between the FX heavy and light chains, and p.Val385Met located in FX peptidase S1 domain) were detected at compound heterozygosis status in three patients with severe bleeding symptoms and FX:C level below 10 IU/dL. Two truncating variants p.Tyr279* and p.Thr434Aspfs*13 leading to an altered FX protein were found at heterozygous state in two patients with mild bleeding history., Conclusion: This study showed the feasibility and the interest of high-throughput sequencing approach for rare bleeding disorders, enabling the report of F10 gene screening in a 3-weeks delay, suitable for clinical use. The description of five new variants may contribute to a better understanding of the phenotype-genotype correlation in FX deficiency., (© 2023 The Authors. Haemophilia published by John Wiley & Sons Ltd.)

Background: Vacuoles, E1 enzyme, X-linked, autoinflammatory, and somatic syndrome is a newly discovered inflammatory disease affecting male subjects, for which few data exist in the literature. Here, we describe the case of a patient with known Sweet's syndrome admitted to the intensive care unit and for whom a vacuoles, E1 enzyme, X-linked, autoinflammatory, and somatic syndrome was diagnosed, allowing for appropriate treatment and the patient's discharge and recovery., Case Presentation: A 70-year-old male White patient was hospitalized in the intensive care unit following an intrahospital cardiac arrest. History started a year before with repeated deep vein thrombosis and episodes of skin eruption compatible with Sweet's syndrome. After a course of oral steroids, fever and inflammatory syndrome relapsed with onset of polychondritis, episcleritis along with neurological symptoms and pulmonary infiltrates. Intrahospital hypoxic cardiac arrest happened during patient's new investigations, and he was admitted in a critical state. During the intensive care unit stay, he presented with livedoid skin lesions on both feet. Vasculitis was not proven; however, cryoglobulinemia screening came back positive. Onset of pancytopenia was explored with a myelogram aspirate. It showed signs of dysmyelopoiesis and vacuoles in erythroid and myeloid precursors. Of note, new deep vein thrombosis developed, despite being treated with heparin leading to the diagnosis of heparin-induced thrombocytopenia. The course of symptoms were overlapping multiple entities, and so a multidisciplinary team discussion was implemented. Screening for UBA1-mutation in the blood came back positive, confirming the vacuoles, E1 enzyme, X-linked, autoinflammatory, and somatic syndrome. Corticosteroids and anti-IL1 infusion were started with satisfactory results supporting patient's discharge from intensive care unit to the internal medicine ward., Conclusions: Vacuoles, E1 enzyme, X-linked, autoinflammatory, and somatic syndrome should be suspected in male patients presenting with inflammatory symptoms, such as fever, skin eruption, chondritis, venous thromboembolism, and vacuoles in bone marrow precursors. Patients with undiagnosed vacuoles, E1 enzyme, X-linked, autoinflammatory, and somatic syndrome may present with organ failure requiring hospitalization in intensive care unit, where screening for UBA1 mutation should be performed when medical history is evocative. Multidisciplinary team involvement is highly recommended for patient management, notably to start appropriate immunosuppressive treatments., (© 2023. The Author(s).)

Tγδ large granular lymphocyte leukemia (LGLL) is a rare variant of T-cell LGLL (T-LGLL) that has been less investigated as compared with the more frequent Tαβ LGLL, particularly in terms of frequency of STAT3 and STAT5b mutations. In this study, we characterized the clinical and biological features of 137 patients affected by Tγδ LGLL; data were retrospectively collected from 1997 to 2020 at 8 referral centers. Neutropenia and anemia were the most relevant clinical features, being present in 54.2% and 49.6% of cases, respectively, including severe neutropenia and anemia in ∼20% of cases each. Among the various treatments, cyclosporine A was shown to provide the best response rates. DNA samples of 97 and 94 cases were available for STAT3 and STAT5b mutation analysis, with 38.1% and 4.2% of cases being mutated, respectively. Clinical and biological features of our series of Tγδ cases were also compared with a recently published Tαβ cohort including 129 cases. Though no differences in STAT3 and STAT5b mutational frequency were found, Tγδ cases more frequently presented with neutropenia (P = .0161), anemia (P < .0001), severe anemia (P = .0065), and thrombocytopenia (P = .0187). Moreover, Vδ2- cases displayed higher frequency of symptomatic disease. Overall, Tγδ cases displayed reduced survival with respect to Tαβ cases (P = .0017). Although there was no difference in STAT3 mutation frequency, our results showed that Tγδ LGLL represents a subset of T-LGLL characterized by more frequent symptoms and reduced survival as compared with Tαβ LGLL., (© 2023 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Low hypodiploidy defines a rare subtype of B-cell acute lymphoblastic leukemia (B-ALL) with a dismal outcome. To investigate the genomic basis of low-hypodiploid ALL (LH-ALL) in adults, we analyzed copy-number aberrations, loss of heterozygosity, mutations, and cytogenetics data in a prospective cohort of Philadelphia (Ph)-negative B-ALL patients (n = 591, ages 18-84 years), allowing us to identify 80 LH-ALL cases (14%). Genomic analysis was critical for evidencing low hypodiploidy in many cases missed by cytogenetics. The proportion of LH-ALL within Ph-negative B-ALL dramatically increased with age, from 3% in the youngest patients (under 40 years old) to 32% in the oldest (over 55 years old). Somatic TP53 biallelic inactivation was the hallmark of adult LH-ALL, present in virtually all cases (98%). Strikingly, we detected TP53 mutations in posttreatment remission samples in 34% of patients. Single-cell proteogenomics of diagnosis and remission bone marrow samples evidenced a preleukemic, multilineage, TP53-mutant clone, reminiscent of age-related clonal hematopoiesis., Significance: We show that low-hypodiploid ALL is a frequent entity within B-ALL in older adults, relying on somatic TP53 biallelic alteration. Our study unveils a link between aging and low-hypodiploid ALL, with TP53-mutant clonal hematopoiesis representing a preleukemic reservoir that can give rise to aneuploidy and B-ALL. See related commentary by Saiki and Ogawa, p. 102. This article is highlighted in the In This Issue feature, p. 101., (©2023 The Authors; Published by the American Association for Cancer Research.)

Blinatumomab is a bispecific T-cell engager approved for B-cell precursor acute lymphoblastic leukemia (B-ALL) with persistent minimal residual disease (MRD) or in relapse. The prognostic impact of tumor load has been suggested before other immunotherapies but remains poorly explored before blinatumomab. We retrospectively analyzed the outcome of 73 patients who received blinatumomab either in first complete remission (CR) with MRD (n=35) or at relapse (n=38). Among MRD patients, 91% had MRD >0.01% before blinatumomab, and 89% achieved complete MRD response after blinatumomab. High pre-blinatumomab MRD levels were associated with shorter relapse-free survival (P=0.049) and overall survival (OS) (P=0.011). At 3 years, OS was 33%, 58% and 86% for pre-blinatumomab MRD >1%, between MRD 0.1- 1% and <0.1% respectively. Among relapsed patients, 23 received blinatumomab with overt relapse and 15 were in complete response (CR) after bridging chemotherapy. At 3 years, overall CR rate was 68% and complete MRD response rate was 84%. Patients who directly received blinatumomab had shorter relapse-free survival (P=0.033) and OS (P=0.003) than patients bridged to blinatumomab. Three-year OS was 66% in the latter group compared to 16% in the former group. Our observations suggest that pre-blinatumomab tumor burden should help to design more tailored strategies including tumor load reduction in relapsed patients.

Background: As a Neglected Tropical Disease associated with Latin America, Chagas Disease (CD) is little known in non-endemic territories of the Americas, Europe and Western Pacific, making its control challenging, with limited detection rates, healthcare access and consequent epidemiological silence. This is reinforced by its biomedical characteristics-it is usually asymptomatic-and the fact that it mostly affects people with low social and financial resources. Because CD is mainly a chronic infection, which principally causes a cardiomyopathy and can also cause a prothrombotic status, it increases the risk of contracting severe COVID-19., Methods: In order to get an accurate picture of CD and COVID-19 overlapping and co-infection, this operational research draws on community-based experience and participative-action-research components. It was conducted during the Bolivian elections in Barcelona on a representative sample of that community., Results: The results show that 55% of the people interviewed had already undergone a previous T. cruzi infection screening-among which 81% were diagnosed in Catalonia and 19% in Bolivia. The prevalence of T. cruzi infection was 18.3% (with 3.3% of discordant results), the SARS-CoV-2 22.3% and the coinfection rate, 6%. The benefits of an integrated approach for COVID-19 and CD were shown, since it only took an average of 25% of additional time per patient and undoubtedly empowered the patients about the co-infection, its detection and care. Finally, the rapid diagnostic test used for COVID-19 showed a sensitivity of 89.5%., Conclusions: This research addresses CD and its co-infection, through an innovative way, an opportunity of systematic integration, during the COVID-19 pandemic., (© 2022. The Author(s).)

Large granular lymphocytic leukemia is a rare lymphoproliferative disorder characterized by a clonal expansion of T-lineage lymphocyte or natural killer (NK) cells in 85 and 15% of cases respectively. T and NK large granular leukemia share common pathophysiology, clinical and biological presentation. The disease is characterized by cytopenia and a frequent association with autoimmune manifestations. Despite an indolent course allowing a watch and wait attitude in the majority of patients at diagnosis, two third of the patient will eventually need a treatment during the course of the disease. Unlike T lymphocyte, NK cells do not express T cell receptor making the proof of clonality difficult. Indeed, the distinction between clonal and reactive NK-cell expansion observed in several situations such as autoimmune diseases and viral infections is challenging. Advances in our understanding of the pathogenesis with the recent identification of recurrent mutations provide new tools to prove the clonality. In this review, we will discuss the pathophysiology of NK large granular leukemia, the recent advances in the diagnosis and therapeutic strategies., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Drillet, Pastoret, Moignet, Lamy and Marchand.)

Introduction: Mutational complexity or tumor mutational burden (TMB) influences the course of chronic lymphocytic leukemia (CLL). However, this information is not routinely used because TMB is usually obtained from whole genome or exome, or from large gene panel high-throughput sequencing., Methods: Here, we used the C-Harrel concordance index to determine the minimum panel of genes for which mutations predict treatment-free survival (TFS) as well as large resequencing panels., Results: An eight gene estimator was defined encompassing ATM, SF3B1, NOTCH1, BIRC3, XPO1, MYD88, TNFAIP3, and TP53. TMB estimated from either a large panel of genes or the eight gene estimator was increased in treated patients or in those with a short TFS (<2 years), unmutated IGHV gene or with an unfavorable karyotype. Being an independent prognostic parameter, any mutation in the eight gene estimator predicted a shorter TFS better than Binet stage and IGHV mutational status among patients with an apparently non-progressive disease (TFS >6 months). Strikingly, the eight gene estimator was also highly informative for patients with Binet stage A CLL or with a good prognosis karyotype., Conclusion: These results suggest that the eight gene estimator, that is easily achievable by high-throughput resequencing, brings robust and valuable information that predicts evolution of untreated patients at diagnosis better than any other parameter., (© 2020 The Authors. International Journal of Laboratory Hematology published by John Wiley & Sons Ltd.)

Distinguishing chronic lymphoproliferative disorders of NK cells (CLPD-NK) from reactive NK-cell expansion is challenging. We assessed the value of killer immunoglobulin-like receptor(KIR) phenotyping and targeted high-throughput sequencing in a cohort of 114 consecutive patients with NK cell proliferation, retrospectively assigned to a CLPD-NK group (n = 46) and a reactive NK group (n = 68). We then developed an NK-cell clonality score combining flow cytometry and molecular profiling with a positive predictive value of 93%. STAT3 and TET2 mutations were respectively identified in 27% and 34% of the patients with CLPD-NK, constituting a new diagnostic hallmark for this disease. TET2-mutated CLPD-NK preferentially exhibited a CD16low phenotype, more frequently displayed a lower platelet count, and was associated with other hematologic malignancies such as myelodysplasia. To explore the mutational clonal hierarchy of CLPD-NK, we performed whole-exome sequencing of sorted, myeloid, T, and NK cells and found that TET2 mutations were shared by myeloid and NK cells in 3 of 4 cases. Thus, we hypothesized that TET2 alterations occur in early hematopoietic progenitors which could explain a potential link between CLPD-NK and myeloid malignancies. Finally, we analyzed the transcriptome by RNA sequencing of 7 CLPD-NK and evidenced 2 groups of patients. The first group displayed STAT3 mutations or SOCS3 methylation and overexpressed STAT3 target genes. The second group, including 2 TET2-mutated cases, significantly underexpressed genes known to be downregulated in angioimmunoblastic T-cell lymphoma. Our results provide new insights into the pathogenesis of NK-cell proliferative disorders and, potentially, new therapeutic opportunities., (© 2021 by The American Society of Hematology.)

Among myeloproliferative neoplasms, polycythemia vera (PV) and essential thrombocythemia (ET) are the 2 entities associated with the most chronic disease course. Leukemic evolution occurs rarely but has a grim prognosis. The interval between diagnosis and leukemic evolution is highly variable, from a few years to >20 years. We performed a molecular evaluation of 49 leukemic transformations of PV and ET by targeted next-generation sequencing. Using a hierarchical classification, we identified 3 molecular groups associated with a distinct time to leukemic transformation. Short-term transformations were mostly characterized by a complex molecular landscape and mutations in IDH1/2, RUNX1, and U2AF1 genes, whereas long-term transformations were associated with mutations in TP53, NRAS, and BCORL1 genes. Studying paired samples from chronic phase and transformation, we detected some mutations already present during the chronic phase, either with a significant allele burden (short-term transformation) or with a very low allele burden (especially TP53 mutations). However, other mutations were not detected even 1 year before leukemic transformation. Our results suggest that the leukemic transformation of PV and ET may be driven by distinct time-dependent molecular mechanisms., (© 2020 by The American Society of Hematology.)

Background: Currently, the recommended tacrolimus (TAC) trough level (Cmin) after liver transplantation (LT) is 6-10 ng/mL (when associated in triple immunosuppressive therapy). However, few studies have achieved the lower limit of this range, especially below 7 ng/mL. This study evaluated the efficacy of a target TAC Cmin of 4-7 ng/mL after LT., Methods: Of 1677 LTs performed between 2002 and 2017, 904 LT cases were analyzed. The cases were categorized into the following 3 groups and compared: low- (n = 247, 27.3%), intermediate- (n = 344, 37.9%), and high-exposure groups (n = 313, 34.5%) with TAC Cmin of 4-7 ng/mL, 7-10 ng/mL, and >10 ng/mL, respectively. In addition, propensity score matching was performed to reduce heterogeneity and population bias., Results: At months 1 and 3, when compared with the 2 other groups, the low-exposure group had similar grafts (P = 0.75) and patient (P = 0.77) survival, but lower alanine aminotransferase (P < 0.001), bilirubin (P < 0.001), international normalized ratio (P = 0.046), and creatinine (P < 0.001) levels. After propensity score matching, the bilirubin (P < 0.001) and creatinine (P = 0.001) levels in the low-exposure group still improved at months 3, but the graft (P = 0.86) and patient (P = 0.99) survival were still similar., Conclusions: A TAC Cmin of 4-7 ng/mL seems safe and capable of improving graft and kidney function. This finding should be confirmed in a prospective randomized trial.

Chagas disease (CHD) has become a challenge in Spain due to the high prevalence of immigrants coming from endemic areas. One of the main difficulties for its control and elimination is its underdiagnosis. The identification and integral treatment of CHD are key to increasing rates of diagnosis, overcoming psycho-social barriers and avoiding CHD progression. Community interventions with in situ screening have proven to be a useful tool in detecting CHD among those with difficulties accessing health services. To determine the underdiagnosis rate of the population most susceptible to CHD among those attending two different Bolivian cultural events celebrated in Barcelona; to describe the sociodemographic characteristics of the people screened; and to analyse the results of the screening. The community interventions were carried out at two Bolivian cultural events held in Barcelona in 2017. Participants were recruited through community health agents. A questionnaire was given to determine the participants' prior knowledge of CHD. In situ screening was offered to those who had not previously been screened. Those who did not wish to be screened were asked for the reason behind their decision. Results were gathered in a database and statistical analyses were performed using STATA v14. 635 interviews were carried out. 95% of the subjects reported prior knowledge of CHD. 271 subjects were screened: 71.2% women and 28.8% men, of whom 87.8% were of Bolivian origin. The prevalence of CHD was 8.9%. Community health interventions with in situ screening are essential to facilitating access to diagnosis.

Introduction: Sideroblastic anemia is a rare cause of microcytic anemia, which is characterized by ring sideroblasts on bone marrow aspirate. This anemia can be congenital or acquired., Case Report: We report the case of an alcoholic 49-year-old man who presented with a severe microcytic sideroblastic anemia related to pyridoxine (B6 vitamin) deficiency. Acid folic deficiency was associated. The blood count normalized within one month after vitamin supplementation., Conclusion: Pyridoxine deficiency must be sought in sideroblastic anemia in patients at risk., (Copyright © 2019 Société Nationale Française de Médecine Interne (SNFMI). Published by Elsevier Masson SAS. All rights reserved.)

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.