Homozygous FVII deficiencies with different reactivity towards tissue thromboplastins of different origin.

The reagents most frequently used for FVII activity assay are obtained by rabbit brain or human placenta. In recent years, human recombinant thromboplastins have received great attention. FVII activity in FVII deficiency is usually low, regardless of the thromboplastin used. There are a few exceptions to this rule. These are represented by FVII Padua (Arg304Gln), FVII Nagoya (Arg304Trp), and FVII (Arg79Gln). In these three instances, clear discrepancies were noted in the FVII activity depending on the thromboplastin used. This indicates that at least two areas of FVII are involved in tissue binding, namely an epidermal growth factor domain of the light chain (Arg79Gln) and the catalytic domain (Arg304), controlled by exons 4 and 8, respectively. Since these three variants are cross reactive material positive, namely they are Type 2 defects, all other variants with normal antigen should be investigated by a panel of at least three tissue thromboplastins (rabbit brain, human tissue or human recombinant, and ox brain derived) in order to obtain a satisfactory classification

An Extensive Quality Control and Quality Assurance (QC/QA) Program Significantly Improves Inter-Laboratory Concordance Rates of Flow-Cytometric Minimal Residual Disease Assessment in Acute Lymphoblastic Leukemia: An I-BFM-FLOW-Network Report

Monitoring of minimal residual disease (MRD) by flow cytometry (FCM) is a powerful prognostic tool for predicting outcomes in acute lymphoblastic leukemia (ALL). To apply FCM-MRD in large, collaborative trials, dedicated laboratory staff must be educated to concordantly high levels of expertise and their performance quality should be continuously monitored. We sought to install a unique and comprehensive training and quality control (QC) program involving a large number of reference laboratories within the international Berlin-Frankfurt-Münster (I-BFM) consortium, in order to complement the standardization of the methodology with an educational component and persistent quality control measures. Our QC and quality assurance (QA) program is based on four major cornerstones: (i) a twinning maturation program, (ii) obligatory participation in external QA programs (spiked sample send around, United Kingdom National External Quality Assessment Service (UK NEQAS)), (iii) regular participation in list-mode-data (LMD) file ring trials (FCM data file send arounds), and (iv) surveys of independent data derived from trial results. We demonstrate that the training of laboratories using experienced twinning partners, along with continuous educational feedback significantly improves the performance of laboratories in detecting and quantifying MRD in pediatric ALL patients. Overall, our extensive education and quality control program improved inter-laboratory concordance rates of FCM-MRD assessments and ultimately led to a very high conformity of risk estimates in independent patient cohorts

Studio dei fattori di rischio genetico nella Trombocitopenia da Eparina

Heparin induced thrombocytopenia (HIT) is a rare and life threatening complication of heparin therapy, characterized by great reduction of platelet’s count, that may be complicated in 30-50% of cases by a paradoxical thrombotic syndrome (HITT), either arterial or venous. As reported by major clinical series in the literature, about 1% of patients receiving unfractionated heparin (UFH) or low molecular weight heparin (LMWH) develop IgG-mediated heparin-induced thrombocytopenia. HIT pathogenesis can be due to antibodies (Abs) formation, which are direct against a complex formed by Heparin (H) and PF4. H/PF4 antibodies bind the platelets receptor FcγRIIA, inducing platelet activation and aggregation, by modulating the affinity of GpIIb-IIIa for fibrinogen and induce release of platelet granules. PECAM-1 has been shown to negatively regulate platelet activation downstream FcγRIIA, but the mechanism of this process is still unclear. Moreover the receptor FcγRIIIA, expressed on macrophages, seems to play an important role on the clearance of IgG-coated platelets. However HIT and HITT does not develop in all patients, different factors may play a role in the onset of clinical syndrome, like: heparin type, antibodies functionality, individual genetic variations (genetic polymorphisms), and in vivo cofactors, such as local trauma. In particular we have studied four different polymorphisms, located in the four receptor previously described: FcγRIIA-H131R, GpIIb/IIIa-HPA1, PECAM1-L125V (in linkage disequilibrium with S563N and R670G) and FcγRIIIA-F158V. The aim of the present study is to understand if polymorphisms of platelets receptors may influence the clinical features of patients who develop H/PF4/Abs, combining immunological, functional and genetic studies. In particular our aim is to discover why some patients with Abs develop HIT syndrome, with or without thrombotic complications, while other not. First we used ELISA commercial test to determine the presence of H/PF4 antibodies in the plasma samples, than we used HIPA as functional test to understand whether the antibodies found were or not able to activate donor’s platelets. Using the 4T score for HIT and the result of immunological and functional test, we define three groups of patients: 51 H/PF4/Ab patients, with antibodies not able to activate platelets and without thrombocytopenia. 50 HIT patients with antibodies able to activate platelets and thrombocytopenia 53 HITT patients with antibodies able to activate platelets, thrombocytopenia and thrombosis. We used molecular biology techniques to determine the genotype for the four polymorphisms previously described, in particular: for FcγRIIA-H131R, PECAM1-L125V and FcγRIIIA-F158V we perform an allele-specific PCR, and for HPA1 polymorphism we set an allelic discrimination real time PCR using taqman probes. Hardy–Weinberg equilibrium was tested for each polymorphism. Allele or genotype frequencies between patients and controls were compared by the χ2 test. Than we use Multiple Regression analysis for multiple confront between different polymorphisms. Comparing the polymorphisms frequencies between the three patients groups (H/PF4/Ab;HIT;HITT) we found some significative differences, in particular between HIT and HITT group. The frequency of the R/R131 genotype (FcγRIIA) is increased in HITT group (p<0,05), the same for the a/b genotype frequency (GpIIIa-HPA1) (p<0,05). The frequency of the polymorphic setting VNG (V/V125-N/N563-G/G670) for the PECAM receptor is also increased in the HITT group compare with the other two groups, but the p value is not statistically significative. We found that R/R131 associated with a/b-HPA1 have a relation with HITT but with a p-value (0,07) near significance. There were no great differences between the genotypes of the four polymorphisms comparing HIT group with H/PF4/Ab group. We suppose that platelets R/R for the receptor FcγRIIA, cleared less efficiently than H/H ones, can circulate longer enhancing the risk for HIT thrombosis. We can suggest that the setting VNG for PECAM1 can have less inhibitory activity on FcγRIIA receptor. Furthermore the b allele for the HPA1 polymorphism is a known risk factor for thrombosis. Together these polymorphisms could create a genetic setting that could enhance thrombotic complications in HIT pathology. We found a p value = 0,07, near significance, for the association of R/R and a/b with HITT (Multiple regression analysis), we think that increasing our cases we could obtain a significant association (p value < 0,05).La piastrinopenia indotta da eparina (HIT) è una rara e grave complicanza della terapia eparinica, caratterizzata da una marcata riduzione del numero delle piastrine (trombocitopenia) che può esere complicata nel 30-50% dei casi da episodi trombotici sia venosi che arteriosi (HITT). La letteratura al riguardo riporta che circa l’1% dei pazienti che ricevono Eparina standard o a basso peso molecolare sviluppano una trombocitopenia da eparina IgG-mediata. L’eziologia della HIT dipende dalla formazione di anticorpi (Abs) rivolti contro un complesso formato da eparina (H), a dosi terapeutiche, e fattore piastrinico 4 (PF4). Gli immunocomplessi H/PF4/Abs che si legano al recettore piastrinico FcγRIIA, inducono attivazione piastrinica e aggregazione, modulando l’affinità della GpIIb/IIIa per il fibrinogeno. PECAM1 regola negativamente l’attivazione piastrinica mediata da FcγRIIA, anche se i meccanismi di tale inibizione non sono ancora stati del tutto chiariti. Le piastrine ricoperte da IgG sono poi riconosciute e rimosse dai macrofagi splenici per mezzo del recettore FcγRIIIA. La HIT e la HITT non si sviluppano in tutti i pazienti che ricevano eparina, numerosi fattori potrebbero giocare un ruolo nella patogenesi: il tipo di eparina utilizzata, l’eterogeneità degli anticorpi, variazioni genetiche interindividuali (polimorfismi) e altri cofattori come stati infiammatori del paziente. In questo studio si sono presi in considerazione in particolare quattro differenti polimorfismi genetici che si trovano sui recettori precedentemente citati: FcγRIIA-H131R, GpIIb/IIIa-HPA1, PECAM1-L125V (in linkage disequilibrium con S563N e R670G) e FcγRIIIA-F158V. L’obiettivo del presente lavoro, combinando studi immunologici, funzionali e genetici, è determinare se i polimorfismi genetici di alcuni recettori piastrinici e monocitari siano implicati nell’insorgenza della HIT o nelle complicanze trombotiche di questa patologia, a parità di presenza di anticorpi E’ stato utilizzato un test ELISA per determinare la presenza degli anticorpi H/PF4 nel plasma dei pazienti e successivamente un test HIPA per determinare se tali anticorpi fossero funzionalmente in grado di attivare le piastrine di donatori in vitro. Utilizzando lo score clinico delle 4T e i risultati dei test immunologico e funzionale, sono stati definiti tre gruppi di pazienti: 51 pazienti H/PF4/Ab, con anticorpi non in grado di attivare le piastrine, senza trombocitopenia. 50 pazienti HIT, con anticorpi funzionalmente in grado di attivare le piastrine e trombocitopenia. 53 pazienti HITT, con anticorpi funzionalmente in grado di attivare le piastrine, trombocitopenia e trombosi. Per determinare il genotipo di tutti i pazienti per i quattro polimorfismi in analisi, sono state utilizzate diverse tecniche di biologia molecolare: per FcγRIIA-H131R, PECAM1-L125V e FcγRIIIA-F158V è stata messa a punto una PCR allele-specifica, per il polimorfismo HPA1, invece, una discriminazione allelica in real time PCR, utilizzando sonde Taqman. Le differenze tra le frequenze alleliche e genotipiche dei tre gruppi di pazienti sono state analizzate con il test statistico del χ2 . Successivamente è stata utilizzata una Multiple Regression Analysis per il confronto tra polimorfismi multipli. Prima di procedere all’analisi statistica è stato testato l’equilibrio di Hardy-Weinberg per ogni polimorfismo. Sono emerse alcune differenze significative confrontando le frequenze dei polimorfismi tra i tre gruppi di pazienti (H/PF4/Ab;HIT;HITT), in particolare tra il gruppo HIT e HITT. La frequenza del genotipo R/R (FcγRIIA) è aumentata nel gruppo HITT (p<0,05), così come la frequenza del genotipo a/b (GpIIIa-HPA1) (p<0,05). Anche la frequenza del setting polimorfico VNG (V/V125-N/N563-G/G670) per il recettore PECAM1 è aumentata nel gruppo HITT rispetto agli altri gruppi, anche se non in modo statisticamente significativo. L’analisi multivariata ha mostrato che l’associazione tra R/R131 e a/b-HPA1 è in relazione con il gruppo HITT, con una p vicina alla significatività statistica (0,07). Non sono state invece rilevate differenze significative per i quattro polimorfismi analizzati tra il gruppo HIT e il gruppo H/PF4/Ab. Possiamo quindi supporre che le piastrine R/R (per il recettore FcγRIIA), eliminate in modo meno efficace delle H/H, rimangano in circolo più a lungo, portando ad un rischio trombotico maggiore nella HIT; tale rischio è aumentato anche dall’allele b di HPA1 (polimorfismo protrombotico per diverse patologie). Si può inoltre ipotizzare che il setting VNG per PECAM 1 possa avere un minor effetto inibitorio sul recettore FcγRIIA. Insieme questi polimorfismi potrebbero creare un setting genetico che porti una maggior frequenza trombotica nella Trombocitopenia da eparina. Per l’associazione dei genotipi R/R e a/b con la HITT, abbiamo ottenuto un valore p=0,07 vicino alla significatività (Multivariate regression analysis); possiamo quindi supporre che aumentando la nostra casistica potremo riuscire ad ottenere un’associazione statisticamente significativa (p<0,05)

Heparin-Induced Thrombocytopenia in Patients with Philadelphia-Negative Myeloproliferative Disorders and Unusual Splanchnic or Cerebral Vein Thrombosis

BACKGROUND: Philadelphia-negative myeloproliferative disorders (Ph-MPD) are common causes of unusual splanchnic or cerebral vein thrombosis, which is treated with unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH). Heparin-induced thrombocytopenia (HIT) is a dangerous potential complication of this therapy, but it has rarely been reported in Ph-MPD. PATIENTS AND METHODS: We retrospectively reviewed clinical records of 29 patients with Ph-MPD who have been treated with UFH or LMWH for unusual splanchnic or cerebral vein thrombosis (3 cerebral sinus, 6 portal and 20 hepatic vein). The goal of the study was to determine the occurrence of new thrombotic events during heparin therapy secondary to HIT (HITT). RESULTS: During heparin therapy, 5 out of the 29 patients (17%) developed a new thrombotic episode (pulmonary embolism) with a high clinical probability of HIT based on the 4 T's score even though not all the patients developed 'true' thrombocytopenia. A diagnosis of HIT was established in 2 patients (6.8%) through the presence of heparin-related antibodies.CONCLUSIONS: Ph-MPD patients on heparin warrant careful monitoring and HIT has to be suspected whenever platelet counts drop or a new thrombosis is detectable

Heparin-induced thrombocytopenia: the role of platelets genetic polymorphisms

Heparin-induced thrombocytopenia (HIT) is a severe complication of heparin therapy, characterized by thrombocytopenia and an increased risk for thrombotic complications secondary to the formation of IgG antibodies (Ab), recognizing a complex of heparin (H) and PF4. Using the 4T clinical score for HIT and the presence of heparin-associated Ab assayed by enzyme-linked immunosorbent assay and heparin-induced platelet aggregation, we define the phenotype of three groups of patients: 51 H/PF4/Ab patients with antibodies and without thrombocytopenia; 50 patients with thrombocytopenia (HIT) and 53 patients with thrombosis (HITT). In these patients we studied four polymorphisms: Fc\u3b3RIIA-H131R, GpIIb/IIIa-HP-1, PECAM1-L125V (in linkage-disequilibrium with S563N and R670G), and Fc\u3b3RIIIA-F158V, to understand if these variations may influence the different phenotypes of the patients. There were no difference in genotype or allele frequencies between controls and the three groups of patients. Afterward, we created a genotype score for multiple risk alleles for thrombosis considering as risk genotype Fc\u3b3RIIA R/R131, HPA-1a/b, and PECAM1-V/V125. These polymorphisms were overrepresented in HITT patients, ascertained by a permutation test (10\u2009000 replicates) p\u2009=\u20090.0198 for the two-single-nucleotide polymorphism (SNP) model and p\u2009=\u20090.0119 for the three-SNP model. The calculated odds ratio for thrombosis was 4.01[CI: 2.30-6.96] in the case of the presence of two at risk genotypes and 8.002 [CI: 4.59-13.93] if all the three at risk genotypes were present. In conclusion these polymorphisms could contribute to the risk of thrombotic complications in HIT

The hematopoietic stem cell marker VNN2 is associated with chemoresistance in pediatric B-cell precursor ALL

Most relapses of acute lymphoblastic leukemia (ALL) occur in patients with a medium risk (MR) for relapse on the Associazione Italiana di Ematologia e Oncologia Pediatrica and Berlin-Frankfurt-Münster (AIEOP-BFM) ALL protocol, based on persistence of minimal residual disease (MRD). New insights into biological features that are associated with MRD are needed. Here, we identify the glycosylphosphatidylinositol-anchored cell surface protein vanin-2 (VNN2; GPI-80) by charting the cell surface proteome of MRD very high-risk (HR) B-cell precursor (BCP) ALL using a chemoproteomics strategy. The correlation between VNN2 transcript and surface protein expression enabled a retrospective analysis (ALL-BFM 2000; N = 770 cases) using quantitative polymerase chain reaction to confirm the association of VNN2 with MRD and independent prediction of worse outcome. Using flow cytometry, we detected VNN2 expression in 2 waves, in human adult bone marrow stem and progenitor cells and in the mature myeloid compartment, in line with proposed roles for fetal hematopoietic stem cells and inflammation. Prospective validation by flow cytometry in the ongoing clinical trial (AIEOP-BFM 2009) identified 10% (103/1069) of VNN2+ BCP ALL patients at first diagnosis, primarily in the MRD MR (48/103, 47%) and HR (37/103, 36%) groups, across various cytogenetic subtypes. We also detected frequent mutations in epigenetic regulators in VNN2+ ALLs, including histone H3 methyltransferases MLL2, SETD2, and EZH2 and demethylase KDM6A. Inactivation of the VNN2 gene did not impair leukemia repopulation capacity in xenografts. Taken together, VNN2 marks a cellular state of increased resistance to chemotherapy that warrants further investigations. Therefore, this marker should be included in diagnostic flow cytometry panels

Long-term proliferation of immature hypoxia-dependent JMML cells supported by a 3D in vitro system

Juvenile myelomonocytic leukemia (JMML) is a rare clonal stem cell disorder that occurs in early childhood and is characterized by the hyperactivation of the RAS pathway in 95% of the patients. JMML is characterized by a hyperproliferation of granulocytes and monocytes, and little is known about the heterogeneous nature of leukemia-initiating cells, as well as of the cellular hierarchy of the JMML bone marrow. In this study, we report the generation and characterization of a novel patient-derived three-dimensional (3D) in vitro JMML model, called patient-derived JMML Atypical Organoid (pd-JAO), sustaining the long-term proliferation of JMML cells with stem cell features and patient-specific hallmarks. JMML cells brewed in a 3D model under different microenvironmental conditions acquired proliferative and survival advantages when placed under low oxygen tension. Transcriptomic and microscopic analyses revealed the activation of specific metabolic energy pathways and the inactivation of processes leading to cell death. Furthermore, we demonstrated the pd-JAO-derived cells' migratory, propagation, and self-renewal capacities. Our study contributes to the development of a robust JMML 3D in vitro model for studying and defining the impact of microenvironmental stimuli on JMML disease and the molecular mechanisms that regulate JMML initiating and propagating cells. Pd-JAO may become a promising model for compound tests focusing on new therapeutic interventions aimed at eradicating JMML progenitors and controlling JMML disease