Publications by authors named "Claire Pouplard"

41 Publications

Prospective evaluation of two specific IgG immunoassays (HemosIL AcuStar HIT-IgG and HAT45G ) for the diagnosis of heparin-induced thrombocytopenia: A Bayesian approach.

Int J Lab Hematol 2020 Nov 27. Epub 2020 Nov 27.

Department of Haematology-Haemostasis, Regional University Hospital of Tours, Tours, France.

Introduction: The accurate diagnosis of heparin-induced thrombocytopenia (HIT) is essential to ensure adequate treatment and prevent complications. First step diagnosis test are immunoassays including enzyme-linked immunosorbent assays (ELISAs) and rapid immunoassays.

Methods: Using a Bayesian approach, we prospectively evaluated the performance of the IgG PF4/polyvinylsulfonate ELISA and a chemiluminescent immunoassay (CLIA), which are specific for IgG and use the same antigenic target to detect HIT antibodies.

Results: One hundred and eighty-four 184 consecutive patients with an intermediate (n = 159) or high (n = 25) clinical pretest probability of HIT based on the 4Ts score or platelet pattern were included. Both immunoassays (IAs) were performed on all 184 samples, and definite HIT was confirmed with a positive serotonin release assay in 29 patients (12.7%). The sensitivity (Ss) and negative predictive value (NPV) of ELISA were excellent (100%) allowing HIT to be excluded with good confidence when the test was negative. In addition, the Ss and NPV of the CLIA equalled 93.1% and 98.6%, respectively, as it was negative in two definite HIT. When the CLIA was negative, the post-test probability of HIT was 0.7% in case of intermediate risk. Although there was excellent agreement between CLIA and ELISA results, the quantitative values provided by the two IAs were not correlated.

Conclusion: AcuStar HIT detects more than 90% of HIT, as do all rapid IAs, and appears to be a good tool for excluding HIT when the pretest probability is intermediate. A chemiluminescent signal higher than 10 IU/mL is highly predictive of definite HIT with a PPV of 100%.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/ijlh.13404DOI Listing
November 2020

Characterization of New Monoclonal PF4-Specific Antibodies as Useful Tools for Studies on Typical and Autoimmune Heparin-Induced Thrombocytopenia.

Thromb Haemost 2021 Mar 21;121(3):322-331. Epub 2020 Oct 21.

Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany.

Background:  Heparin-induced thrombocytopenia (HIT) is typically caused by platelet-activating immunoglobulin G (IgG) antibodies (Abs) against platelet factor 4 (PF4) complexed with heparin (H). Much less frequent "autoimmune" HIT is distinguished from typical HIT by platelet activation without heparin and the presence of both anti-PF4/H and anti-PF4 IgG. We developed three murine monoclonal anti-PF4 Abs with a human Fc-part, 1E12, 1C12, and 2E1, resembling autoimmune HIT Abs.

Objectives:  To characterize 1E12, 1C12, and 2E1 in comparison to the heparin-dependent monoclonal anti-PF4/H Abs 5B9 and KKO, and polyclonal Abs from patients with typical HIT (group-2) and autoimmune HIT (group-3).

Methods:  Interactions of Abs with PF4 and PF4/H were studied by enzyme-linked-immunosorbent assay, single-molecule force spectroscopy, isothermal titration calorimetry, and dynamic light scattering. Serotonin release assay and heparin-induced platelet activation assay were used to assess platelet activation. The binding sites of monoclonal Abs on PF4 were predicted in silico (MAbTope method).

Results:  1C12, 1E12, and 2E1 displayed higher affinity for PF4/H complexes than 5B9 and KKO, comparable to human group-3 Abs. Only 1C12, 1E12, 2E1, and group-3 Abs formed large complexes with native PF4, and activated platelets without heparin. The predicted binding sites of 1C12, 1E12, and 2E1 on PF4 differed from those of KKO and 5B9, but were close to each other. 2E1 exhibited unique bivalent binding, involving its antigen recognition site to PF4 and charge-dependent interactions with heparin.

Conclusion:  1C12, 1E12, and 2E1 are tools for studying the pathophysiology of autoimmune HIT. 2E1 provides evidence for a new binding mechanism of HIT Abs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1055/s-0040-1717078DOI Listing
March 2021

Acquired platelet defect associated with gabapentin treatment: a case-report.

Platelets 2020 Aug 22:1-4. Epub 2020 Aug 22.

Department of Haemostasis, University Hospital of Tours , Tours, France.

Gabapentin, a structural analog of gamma-aminobutyric acid, is used to treat peripheral neuropathic pain. Here we report the first case of platelet function disorder associated with gabapentin treatment in a 44-year-old woman without a history of bleeding. She presented with mucocutaneous bleeding approximately 1 month after initiation of gabapentin and platelet function tests showed no aggregation to arachidonic acid and epinephrine, a defective response to ADP and a slightly decreased response to collagen. Gabapentin's imputability was supported by the fact that all platelet functions were normalized 6 days after drug discontinuation, with the simultaneous disappearance of bleedings.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/09537104.2020.1809645DOI Listing
August 2020

Emicizumab treatment: Impact on coagulation tests and biological monitoring of haemostasis according to clinical situations (BIMHO group proposals).

Eur J Haematol 2020 Dec 16;105(6):675-681. Epub 2020 Sep 16.

Laboratoire d'hématologie générale, Hôpital Necker, AP-HP, Paris, France.

Emicizumab, a bispecific humanised monoclonal antibody restoring to some extent the function of activated FVIII deficient in haemophilia A, represents a major therapeutic advance in the management of haemophilia A patients. No dosage adjustment is required, which leads to a major change for patients used to regular biological monitoring which is particularly burdensome in the case of substitution therapy. In some circumstances, such as before an invasive procedure or in case of bleeding, biological monitoring will be necessary and emicizumab's interference with haemostasis tests, particularly those based on an activated partial thromboplastin times (aPTT), must be known to best interpret the tests and to select the most appropriate methods to guide therapy. The normalisation of aPTT in patients treated with emicizumab is not sufficient to consider haemostasis as normalised. In the event of administration of FVIII to a patient receiving emicizumab, the determination of FVIII should use a chromogenic method using non-human reagents. Coagulation global tests have been proposed to evaluate the biological response when using bypassing agents in patients treated with emicizumab, but the usefulness must be confirmed. The French group BIMHO presents proposals for biological monitoring of a patient treated with emicizumab according to clinical situations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/ejh.13490DOI Listing
December 2020

Comparative Analysis of a French Prospective Series of 144 Patients with Heparin-Induced Thrombocytopenia (FRIGTIH) and the Literature.

Thromb Haemost 2020 Jul 22;120(7):1096-1107. Epub 2020 Jun 22.

EA 7501, GICC, Université de Tours, Tours, France.

Background:  Heparin-induced thrombocytopenia (HIT) is a rare complication of heparin treatments, and only a few large patient cohorts have been reported. In this study, biological and clinical data from 144 French patients with HIT were analyzed in comparison with the literature.

Methods:  The diagnosis of HIT was confirmed in all patients by an immunoassay combined with serotonin release assay. In the literature, only cohorts of at least 20 HIT patients published from 1992 were selected for a comparative analysis.

Results:  Two-thirds of patients were hospitalized in surgery and most were treated with unfractionated heparin (83.2% vs. 16.8% with low molecular weight heparin only). Thrombotic events in 54 patients (39.7%) were mainly venous (41/54). However, arterial thrombosis was more frequent after cardiac surgery (13.2% vs. 2.4% in other surgeries,  = 0.042) with a shorter recovery time (median = 3 vs. 5 days,  < 0.001). The mortality rate was lower in our series than in the 22 selected published studies (median = 6.3% vs. 15.9%). Three genetic polymorphisms were also studied and homozygous subjects FcγRIIA RR were more frequent in patients with thrombosis (37.8 vs. 18.2% in those without thrombosis,  = 0.03).

Conclusion:  This study shows that the mortality rate due to HIT has recently decreased in France, possibly due to earlier diagnosis and improved medical care. It also confirms the strong association between polymorphism FcγRIIA H131R and thrombosis in HIT.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1055/s-0040-1712957DOI Listing
July 2020

Detection of Platelet-Activating Antibodies Associated with Heparin-Induced Thrombocytopenia.

J Clin Med 2020 Apr 24;9(4). Epub 2020 Apr 24.

Department of Hemostasis, University Hospital of Tours, 37044 Tours, France.

Heparin-induced thrombocytopenia (HIT) is a prothrombotic immune drug reaction caused by platelet-activating antibodies that in most instances recognize platelet factor 4 (PF4)/polyanion complexes. Platelet activation assays (i.e., functional assays) are more specific than immunoassays, since they are able to discern clinically relevant heparin-induced antibodies. All functional assays used for HIT diagnosis share the same principle, as they assess the ability of serum/plasma from suspected HIT patients to activate fresh platelets from healthy donors in the presence of several concentrations of heparin. Depending on the assay, donors' platelets are stimulated either in whole blood (WB), platelet-rich plasma (PRP), or in a buffer medium (washed platelets, WP). In addition, the activation endpoint studied varies from one assay to another: platelet aggregation, membrane expression of markers of platelet activation, release of platelet granules. Tests with WP are more sensitive and serotonin release assay (SRA) is considered to be the current gold standard, but functional assays suffer from certain limitations regarding their sensitivity, specificity, complexity, and/or accessibility. However, the strict adherence to adequate preanalytical conditions, the use of selected platelet donors and the inclusion of positive and negative controls in each run are key points that ensure their performances.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/jcm9041226DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7230370PMC
April 2020

Real Life Population Pharmacokinetics Modelling of Eight Factors VIII in Patients with Severe Haemophilia A: Is It Always Relevant to Switch to an Extended Half-Life?

Pharmaceutics 2020 Apr 21;12(4). Epub 2020 Apr 21.

Department of Medical Pharmacology, University Hospital of Reims, EA3801, SFR Cap-Santé, University of Reims, 51100 Reims, France.

We retrospectively analysed the data files of 171 adults and 87 children/adolescents with severe haemophilia, except for 14 patients (moderate; minor) (1), to develop a global population pharmacokinetic (PK) model for eight factors VIII (FVIII) that could estimate individual PK parameters for targeting the desired level of FVIII activity (FVIII:C); and (2) to compare half-life (HL) in patients switching from a standard half-life (SHL) to an extended half-life (EHL) and evaluate the relevance of the switch. One-stage clotting assay for the measurement of FVIII activity (FVIII:C, IU/mL) was used for population PK modelling. The software, Monolix version 2019R1, was used for non-linear mixed-effects modelling. A linear two-compartment model best described FVIII:C. The estimated PK parameters (between-subject variability) were: 2640 mL (23.2%) for volume of central compartment (V1), 339 mL (46.8%) for volume of peripheral compartment (V2), 135 mL/h for Q (fixed random effect), and 204 mL/h (34.9%) for clearance (Cl). Weight, age, and categorical covariate EHL were found to influence Cl and only weight for V1. This model can be used for all of the FVIII cited in the study. Moreover, we demonstrated, in accordance with previous studies, that Elocta had longer half-life (EHL) than SHL (mean ratio: 1.48) as compared to Advate, Factane, Kogenate, Novoeight, and Refacto.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/pharmaceutics12040380DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7238177PMC
April 2020

Diagnosis and management of heparin-induced thrombocytopenia.

Anaesth Crit Care Pain Med 2020 04 13;39(2):291-310. Epub 2020 Apr 13.

Service d'anesthésie-réanimation, hôpital européen Georges-Pompidou, INSERM UMRS-1140, université Paris Descartes, 25, rue Leblanc, 75015 Paris, France. Electronic address:

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.accpm.2020.03.012DOI Listing
April 2020

Factor VIII and IX assays for post-infusion monitoring in hemophilia patients: Guidelines from the French BIMHO group (GFHT).

Eur J Haematol 2020 Aug 27;105(2):103-115. Epub 2020 May 27.

Service d'Hématologie Hémostase, Hospices Civils de Lyon, Bron, France.

Replacement therapy with plasma-derived or recombinant FVIII and FIX (pdFVIII/pdFIX or rFVIII/rFIX) concentrates is the standard of treatment in patients with haemophilia A and B, respectively. Measurement of factor VIII (FVIII:C) or factor IX (FIX:C) levels can be done by one-stage clotting assay (OSA) or chromogenic substrate assay (CSA). The French study group on the Biology of Hemorrhagic Diseases (a collaborative group of the GFHT and MHEMO network) presents a literature review and proposals for the monitoring of FVIII:C and FIX:C levels in treated haemophilia A and B patients, respectively. The use of CSA is recommended for the monitoring of patients treated with pdFVIII or rFVIII including extended half-life (EHL) rFVIII. Except for rFVIII-Fc, great caution is required when measuring FVIII:C levels by OSA in patients substituted by EHL-rFVIII. The OSA is recommended for the monitoring of patients treated with pdFIX or rFIX. Large discordances in the FIX:C levels measured for extended half-life rFIX (EHL-rFIX), depending on the method and reagents used, must lead to great attention when OSA is used for measuring FIX:C levels in patients substituted by EHL-rFIX. Data of most of recent studies, obtained with spiked plasmas, deserve to be confirmed in plasma samples of treated patients.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/ejh.13423DOI Listing
August 2020

Multicentre pharmacokinetic evaluation of rFVIII-Fc (efmoroctocog alfa) in a real life and comparison with non-extended half-life FVIII concentrates.

Haemophilia 2020 Mar 27;26(2):282-289. Epub 2020 Feb 27.

Laboratoire d'Hémostase Hémobiologie, CHU de Lille, Lille, France.

The use of enhanced half-life (EHL) FVIII has improved the quality of prophylaxis in haemophilia A, but with a benefit that may vary from one patient to another. We analysed the pharmacokinetic data obtained with efmoroctocog alfa (rFVIII-Fc) in 114 patients and, in 47 cases, compared them to those previously measured with non-EHL FVIII. The in vivo recovery (IVR) of rFVIII-Fc measured with one stage clotting assay (OSA) and chromogenic assay (CSA) was 2.2 and 2.8 IU/mL per IU/kg, respectively. The median half-life (T ) of rFVIII-Fc was 14.5 hours whatever the FVIII:C assay used, but variable and correlated with preinfusion VWF:Ag levels (r = .76). Both IVR and T were lower in patients under 12 years old (2.4 IU/mL per IU/kg and 11.1 hours, respectively; CSA). PK study of rFVIII-Fc vs non-EHL FVIII showed a T ratio of 1.4 in favour of rFVIII-Fc, regardless of the patient's age. However the relative increase in T with rFVIII-Fc was lower than 30% in one-third of patients evaluated, particularly when the previous FVIII administered was a BHK-derived product. This study therefore suggests that analysis of individual PK profile in response to a specific FVIII concentrate is potentially useful before a switch in haemophilia A patients.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/hae.13946DOI Listing
March 2020

Evaluation of functional assays for the diagnosis of heparin induced thrombocytopenia using 5B9, a monoclonal IgG that mimics human antibodies.

J Thromb Haemost 2020 04 20;18(4):968-975. Epub 2020 Feb 20.

Department of Haemostasis, University Hospital of Tours, Tours, France.

Background: Serotonin release assay (SRA) is considered as the "gold standard" for detecting pathogenic heparin-induced thrombocytopenia (HIT) antibodies. However, this method is time consuming, expensive, and uses radioelements. Heparin-induced multiple electrode aggregometry (HIMEA), light transmission aggregometry (LTA) with platelet rich plasma (PRP) or washed platelets (WP), adenosine triphosphate (ATP) release, and flow cytometry (FC) are available alternatives.

Objectives: To evaluate the performance of these assays, comparatively with SRA, for detecting HIT antibodies, using 5B9, a monoclonal IgG fully mimicking human HIT antibodies.

Patients/methods: Heparin-dependent platelet activation induced by 5B9 (50/20/10 µg/mL) was evaluated by all assays performed on the same day using platelets from 20 healthy donors. The three methods exhibiting the highest sensitivity to 5B9 were then assessed by testing samples from patients with either likely (n = 10), or indeterminate/unlikely HIT (n = 10).

Results: All methods exhibited good sensitivity for detecting 5B9 50 µg/mL, but only SRA and HIMEA were positive with 100% of donors using 5B9 20 µg/mL, followed by FC (83%). SRA detected 5B9 10 μg/mL with 90% of donors, while HIMEA and FC were positive in 45% and 44% of cases, respectively. Whereas SRA was positive with 9/10 samples from likely HIT, HIMEA and FC were positive with 6 and 7 of them, respectively. Neither SRA nor HIMEA was positive with indeterminate/unlikely HIT samples, while FC was positive or doubtful in three cases.

Conclusions: Serotonin release assay likely remains the most sensitive and specific assay for detecting platelet activating HIT antibodies, but HIMEA or FC are potential alternatives, despite being less performant.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/jth.14749DOI Listing
April 2020

Frequency and Clinical Impact of Platelet Factor 4-Specific Antibodies in Patients Undergoing Extracorporeal Membrane Oxygenation.

Thromb Haemost 2019 Jul 26;119(7):1138-1146. Epub 2019 May 26.

University Hospital of Tours, Department of Hemostasis, Tours, France.

Introduction/objectives:  Extracorporeal membrane oxygenation (ECMO) provides circulatory support in patients with severe heart failure, but the frequent use of unfractionated heparin exposes patients to high risk of heparin-induced thrombocytopenia (HIT). We prospectively evaluated the development and clinical impact of platelet factor 4 (PF4)-specific antibodies (Abs) during ECMO and whether specific biological characteristics could predict HIT.

Materials And Methods:  From 2014 to 2018, we studied 57 adults who underwent an ECMO for at least 5 days. The plasma samples collected daily were tested for PF4-specific Abs using immunoassays to detect immunoglobulin (Ig) G, A, and M isotypes or only IgG. Serotonin release assay was performed without and with PF4 to detect pathogenic Abs.

Results:  Twenty-nine patients (50%) were positive for PF4-specific Abs (IgG, A, M), with IgG in 17/57 (30%) and 16 of them (94%) were immunized within 10 days. PF4-specific IgG Abs did not affect the clinical or biological course of most patients. HIT was suspected in only two patients with ECMO circuit dysfunction and unexpected platelet count decrease after day 5. High levels of PF4-specific IgG were detected in both patients, and HIT was confirmed by a serotonin release assay, which was also more sensitive when exogenous PF4 was present.

Conclusion:  PF4-specific Abs are common during ECMO but are mostly non-pathogenic and not associated with a less favorable prognosis. However, an abnormal platelet count evolution, in particular if associated with ECMO circuit dysfunction, should prompt the search for pathogenic PF4-specific IgG.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1055/s-0039-1688827DOI Listing
July 2019

Estimation of Nuwiq (simoctocog alfa) activity using one-stage and chromogenic assays-Results from an international comparative field study.

Haemophilia 2019 Jul 20;25(4):708-717. Epub 2019 May 20.

Institut für Experimentelle Hämatologie und Transfusionsmedizin, Universitätsklinikum Bonn, Bonn, Germany.

Background: Accurate determination of coagulation factor VIII activity (FVIII:C) is essential for effective and safe FVIII replacement therapy.

Fviii: C can be measured by one-stage and chromogenic substrate assays (OSAs and CSAs, respectively); however, there is significant interlaboratory and interassay variability.

Aims: This international comparative field study characterized the behaviour of OSAs and CSAs used in routine laboratory practice to measure the activity of Nuwiq (human-cl rhFVIII, simoctocog alfa), a fourth-generation recombinant human FVIII produced in a human cell line.

Methods: FVIII-deficient plasma was spiked with Nuwiq or Advate at 1, 5, 30 and 100 international units (IU)/dL. Participating laboratories analysed the samples using their routine procedures and equipment. Accuracy, inter- and intralaboratory variation, CSA:OSA ratio and the impact of different OSA and CSA reagents were assessed.

Results: Forty-nine laboratories from 9 countries provided results. Mean absolute FVIII:C was comparable for both products at all concentrations with both OSA and CSA, with interproduct ratios (Nuwiq :Advate ) of 1.02-1.13. Mean recoveries ranged from 97% to 191% for Nuwiq , and from 93% to 172% for Advate , with higher recoveries at lower concentrations. Subgroup analyses by OSA and CSA reagents showed minor variations depending on reagents, but no marked differences between the two products. CSA:OSA ratios based on overall means ranged from 0.99 to 1.17 for Nuwiq and from 1.01 to 1.17 for Advate .

Conclusions: Both OSAs and CSAs are suitable for the measurement of FVIII:C of Nuwiq in routine laboratory practice, without the need for a product-specific reference standard.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/hae.13763DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6851970PMC
July 2019

Cleavage of anti-PF4/heparin IgG by a bacterial protease and potential benefit in heparin-induced thrombocytopenia.

Blood 2019 05 27;133(22):2427-2435. Epub 2019 Mar 27.

EA 7501, Innovation and Cell Targeting Group, Université de Tours, Tours, France.

Heparin-induced thrombocytopenia (HIT) is due to immunoglobulin G (IgG) antibodies, which bind platelet factor 4 (PF4) modified by polyanions, such as heparin (H). IgG/PF4/polyanion complexes directly activate platelets via Fc gamma type 2 receptor A (FcγRIIA) receptors. A bacterial protease, IgG-degrading enzyme of (IdeS), cleaves the hinge region of heavy-chain IgG, abolishing its ability to bind FcγR, including FcγRIIA. We evaluated whether cleavage of anti-PF4/H IgG by IdeS could suppress the pathogenicity of HIT antibodies. IdeS quickly cleaved purified 5B9, a monoclonal chimeric anti-PF4/H IgG1, which led to the formation of single cleaved 5B9 (sc5B9), without any reduction in binding ability to the PF4/H complex. However, as compared with uncleaved 5B9, the affinity of sc5B9 for platelet FcγRIIA was greatly reduced, and sc5B9 was also unable to induce heparin-dependent platelet activation. In addition, incubating IdeS in whole blood containing 5B9 or HIT plasma samples led to cleavage of anti-PF4/H antibodies, which fully abolished the ability to induce heparin-dependent platelet aggregation and tissue factor messenger RNA synthesis by monocytes. Also, when whole blood was perfused in von Willebrand factor-coated microfluidic channels, platelet aggregation and fibrin formation induced by 5B9 with heparin was strongly reduced after IdeS treatment. Finally, IdeS prevented thrombocytopenia and hypercoagulability induced by 5B9 with heparin in transgenic mice expressing human PF4 and FcγRIIA receptors. In conclusion, cleavage of anti-PF4/H IgG by IdeS abolishes heparin-dependent cellular activation induced by HIT antibodies. IdeS injection could be a potential treatment of patients with severe HIT.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1182/blood.2019000437DOI Listing
May 2019

Etiology and Outcomes of Thrombotic Microangiopathies.

Clin J Am Soc Nephrol 2019 04 12;14(4):557-566. Epub 2019 Mar 12.

Service de Néphrologie-hypertension, Dialyses, Transplantation Rénale, Hôpital Bretonneau et hôpital Clocheville,

Background And Objectives: Thrombotic microangiopathies constitute a diagnostic and therapeutic challenge. Secondary thrombotic microangiopathies are less characterized than primary thrombotic microangiopathies (thrombotic thrombocytopenic purpura and atypical hemolytic and uremic syndrome). The relative frequencies and outcomes of secondary and primary thrombotic microangiopathies are unknown.

Design, Setting, Participants, & Measurements: We conducted a retrospective study in a four-hospital institution in 564 consecutive patients with adjudicated thrombotic microangiopathies during the 2009-2016 period. We estimated the incidence of primary and secondary thrombotic microangiopathies, thrombotic microangiopathy causes, and major outcomes during hospitalization (death, dialysis, major cardiovascular events [acute coronary syndrome and/or acute heart failure], and neurologic complications [stroke, cognitive impairment, or epilepsy]).

Results: We identified primary thrombotic microangiopathies in 33 of 564 patients (6%; thrombotic thrombocytopenic purpura: 18 of 564 [3%]; atypical hemolytic and uremic syndrome: 18 of 564 [3%]). Secondary thrombotic microangiopathies were found in 531 of 564 patients (94%). A cause was identified in 500 of 564 (94%): pregnancy (35%; 11 of 1000 pregnancies), malignancies (19%), infections (33%), drugs (26%), transplantations (17%), autoimmune diseases (9%), shiga toxin due to (6%), and malignant hypertension (4%). In the 31 of 531 patients (6%) with other secondary thrombotic microangiopathies, 23% of patients had sickle cell disease, 10% had glucose-6-phosphate dehydrogenase deficiency, and 44% had folate deficiency. Multiple causes of thrombotic microangiopathies were more frequent in secondary than primary thrombotic microangiopathies (57% versus 19%; <0.001), and they were mostly infections, drugs, transplantation, and malignancies. Significant differences in clinical and biologic differences were observed among thrombotic microangiopathy causes. During the hospitalization, 84 of 564 patients (15%) were treated with dialysis, 64 of 564 patients (11%) experienced major cardiovascular events, and 25 of 564 patients (4%) had neurologic complications; 58 of 564 patients (10%) died, but the rates of complications and death varied widely by the cause of thrombotic microangiopathies.

Conclusions: Secondary thrombotic microangiopathies represent the majority of thrombotic microangiopathies. Multiple thrombotic microangiopathies causes are present in one half of secondary thrombotic microangiopathies. The risks of dialysis, neurologic and cardiac complications, and death vary by the cause of thrombotic microangiopathies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2215/CJN.11470918DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6450353PMC
April 2019

[Factor VIII assays in treated hemophilia A patients].

Ann Biol Clin (Paris) 2019 02;77(1):53-65

CHU Lille, Institut d'hématologie-transfusion, Inserm U1011, Lille, France.

Replacement therapy with plasma-derived or recombinant FVIII (pdFVIII or rFVIII) concentrates is the standard of treatment in patients with hemophilia A. The reference method used for measuring factor VIII (FVIII:C) levels in patients treated by FVIII concentrates is the chromogenic substrate assay (CSA). However, the one-stage clotting assay (OSA) is predominantly used in current clinical practice, but this method depends on the activated partial thromboplastin time (APTT) reagent and the coagulation analyzer used, and wide variations in the measurements of FVIII recovery have been reported with some factor concentrates. The French study group on the biology of hemorrhagic diseases (a collaborative group of the GFHT and MHEMO network) presents a review of the literature and proposals for the monitoring of FVIII:C levels in treated hemophilia A patients. The use of CSA calibrated with a plasma reference tested against the current FVIII WHO (World Health Organization) International Standard is recommended for the monitoring of patients treated with pdFVIII or rFVIII including extended half-life (EHL) rFVIII. OSA are adequate for the monitoring of patients treated with pdFVIII or with most of rFVIII concentrates. However, preliminary comparison with CSA is mandatory before measuring FVIII:C by OSA in patients treated by Refacto AF. For rFVIII-EHL, OSA are only acceptable for Elocta®. Great caution is therefore required when measuring FVIII:C levels by OSA in patients substituted by other EHL-rFVIII. Indeed, most of recent studies reported data obtained with spiked plasmas, which deserve to be confirmed on plasma samples collected in treated patients.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1684/abc.2019.1413DOI Listing
February 2019

[Factor IX assays in treated hemophilia B patients].

Ann Biol Clin (Paris) 2019 02;77(1):41-52

Service d'hématologie hémostase, Hospices civils de Lyon, Bron, France.

Replacement therapy with plasma-derived or recombinant FIX (pdFIX or rFIX) concentrates is the standard of treatment in patients with hemophilia B. The method predominantly used for measuring factor IX (FIX:C) levels is the one-stage clotting assay (OSA) but this method depends on the activated partial thromboplastin time (APTT) reagent and the coagulation analyzer used, and wide variations in the measurements of FIX recovery have been reported with some factor concentrates. The French study group on the biology of hemorrhagic diseases (a collaborative group of the GFHT and MHEMO network), presents a review of the literature and proposals for the monitoring of FIX:C levels in treated hemophilia B patients. The use of OSA calibrated with a plasma reference tested against the current FIX WHO International Standard is recommended for the monitoring of patients treated with pdFIX or rFIX. Chromogenic substrate assays (CSA) are adequate for the monitoring of patients treated with Rixubis, but data available for Benefix are currently too limited. For extended half-life rFIX (EHL-rFIX), large discordances in the FIX:C levels measured were evidenced, depending on the method and reagents used. Great attention is therefore required for measuring FIX:C levels by OSA in patients substituted by EHL-rFIX. Commercial kits for CSA are not equivalent, and although potentially useful, they are not validated for all EHL-rFIX. Most of recent studies reported data obtained with spiked plasmas, which deserve to be confirmed on plasma samples collected in treated patients.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1684/abc.2019.1414DOI Listing
February 2019

Beneficial effect of exogenous platelet factor 4 for detecting pathogenic heparin-induced thrombocytopenia antibodies.

Br J Haematol 2017 12 19;179(5):811-819. Epub 2017 Oct 19.

Department of Haematology-Haemostasis, University Hospital of Tours, Tours, France.

The laboratory diagnosis of heparin-induced thrombocytopenia (HIT) is based on an enzyme immunoassay combined with a functional test, and serotonin release assay (SRA) is the gold standard for detecting activating HIT antibodies. However, a recent atypical history of HIT prompted us to evaluate whether addition of platelet factor 4 (PF4) during SRA could improve its ability to detect pathogenic HIT antibodies. Using 5B9, a monoclonal antibody to PF4/H with a human Fc fragment, we first defined the optimal PF4 concentration for detecting low amounts of platelet-activating IgG with SRA. Plasma samples from 50 patients with suspected HIT were then studied, and SRA was positive in 17 cases (Group SRA ), with relatively high levels of PF4-specific IgG (median optical density = 2·66). SRA was also systematically performed after adding 10 μg/ml of PF4 in the reaction mixture, and significant serotonin release was measured with samples from 9 additional patients (Group PF4-SRA ). Importantly, levels of PF4-specific IgG were similar in these samples and those from the 24 persistently SRA negative patients. Moreover, the pre-test probability of HIT was intermediate/high in all 'SRA ' or 'SRA-PF4 ' patients. In conclusion, addition of exogenous PF4 might improve the detection of pathogenic HIT antibodies by SRA.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/bjh.14955DOI Listing
December 2017

Risk factors for heparin-induced thrombocytopenia: Focus on Fcγ receptors.

Thromb Haemost 2016 Oct 30;116(5):799-805. Epub 2016 Jun 30.

Yves Gruel, Service d'Hématologie-Hémostase, Hôpital Trousseau, CHU de Tours, 37044 Tours Cedex, France, Tel.: +33 02 47 47 46 72, E-mail:

Fcγ receptors have critical roles in the pathophysiology of heparin-induced thrombocytopenia (HIT), a severe immune-mediated complication of heparin treatment. Activation of platelets, monocytes and neutrophils by platelet-activating anti-PF4/heparin IgG antibodies results in thrombocytopenia, hypercoagulability and thrombosis in susceptible patients, effects that depend on FcγRIIA. In addition, FcγRIIIA receptors probably contribute to clearance of platelets sensitised by HIT immune complexes. FcγRI has also been reported to be involved in monocyte activation by HIT IgG antibodies and synthesis of tissue factor. This review focuses on the role of these FcγRs in HIT pathophysiology, including the potential influence of several gene variations associated with variable risk of HIT and related thrombosis. In particular, the 276P and 326Q alleles of CD148, a protein tyrosine phosphatase that regulates FcγRIIA signalling, are associated with a lower risk of HIT, and platelets from healthy donors expressing these alleles are hyporesponsive to anti-PF4/H antibodies. It was also recently demonstrated that the risk of thrombosis is higher in HIT patients expressing the R isoform of the FcγRIIA H131R polymorphism, with HIT antibodies shown to activate RR platelets more efficiently, mainly explained by an inhibitory effect of normal IgG2, which bound to the FcγRIIA 131H isoform more efficiently. Environmental risk factors probably interact with these gene polymorphisms affecting FcγRs, thereby increasing thrombosis risk in HIT.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1160/TH16-02-0109DOI Listing
October 2016

No impact of PTPN22, PTPRJ and ACP1 genes polymorphisms on the risk of immune thrombocytopenia in French adult patients.

Thromb Res 2016 Aug 25;144:76-8. Epub 2016 Apr 25.

Unité Mixte de Recherche Centre National de la Recherche Scientifique 7292 and Université François Rabelais, Tours, France; Department of Hematology-Hemostasis, Trousseau hospital, Tours, France. Electronic address:

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.thromres.2016.04.013DOI Listing
August 2016

[Use of heparin and its derivatives in nursing care].

Soins 2016 Mar(803):23-8

Service d'hématologie-hémostase, hôpital Trousseau, 37044 Tours Cedex, France; Unité de soins cardiaque intensifs, hôpital Trousseau, 37044 Tours Cedex, France; UFR Sciences pharmaceutiques, 31 avenue Monge, 37200 Tours, France. Electronic address:

Heparin is an injectable anti-coagulant indicated in the treatment of venous thromboembolic diseases. In the case of major kidney failure, unfractionated heparins (UFHs) can be administered while low molecular weight heparins (LMWHs) are contraindicated at a curative dose. Platelet count must be monitored in patients treated with UFHs and when an LMWH is prescribed in a surgical context.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.soin.2015.10.026DOI Listing
March 2016

A rapid test (STic Expert® ) for the diagnosis of heparin-induced thrombocytopenia--response to De Cooman and Devreese.

Br J Haematol 2016 Feb 11;172(3):466-7. Epub 2015 May 11.

UMR CNRS 7292 and Université François Rabelais, Tours, France.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/bjh.13490DOI Listing
February 2016

Increased risk of thrombosis in FcγRIIA 131RR patients with HIT due to defective control of platelet activation by plasma IgG2.

Blood 2015 Apr 13;125(15):2397-404. Epub 2015 Feb 13.

Unité Mixte de Recherche 7292, Centre National de la Recherche Scientifique, Université François Rabelais, Tours, France; Laboratoire d'Hématologie-Hémostase, and.

Thrombosis results in heparin-induced thrombocytopenia (HIT) from cellular activation involving Fc receptors. In this study, the FcγRIIA 131RR genotype was found to increase the risk of thrombosis in HIT patients (odds ratio: 5.9; 95% confidence interval: 1.7-20). When platelet aggregation tests (PATs) were performed with platelet-rich plasma (PRP), a shorter lag time was measured in 131RR donors compared to individuals with the HR and HH genotypes in response to HIT plasma or 5B9, a recently developed humanized monoclonal antibody to PF4/heparin. Importantly, this difference was no longer detectable when PATs were performed with washed platelets or immunoglobulin (Ig)G-depleted PRP. Moreover, polyclonal IgG or monoclonal IgG1 added to IgG-depleted PRP increased the lag time in response to 5B9. HH platelets were also sensitive to IgG2, which in contrast, failed to inhibit the response of 131RR platelets to 5B9. Finally, higher tissue factor messenger RNA levels were measured in the whole blood of 131RR donors after activation by HIT antibodies, with increased phospholipid procoagulant activity. These results demonstrate that HIT patients homozygous for the FcγRIIA 131R allele have a higher risk of thrombosis, probably due to increased cell activation by antibodies to PF4/heparin, with a lower inhibitory effect of endogenous IgG, especially from the IgG2 subclass.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1182/blood-2014-09-594515DOI Listing
April 2015

A genome-wide association study of heparin-induced thrombocytopenia using an electronic medical record.

Thromb Haemost 2015 Apr 11;113(4):772-81. Epub 2014 Dec 11.

Dan M. Roden, MD, MRB4 1285B, 2215B Garland Avenue, Nashville, TN, 37232-0575, USA, Tel.: +1 615 322 0067, Fax: +1 615 343 4522, E-mail:

Heparin-induced thrombocytopenia (HIT) is an unpredictable, potentially catastrophic adverse effect of heparin treatment resulting from an immune response to platelet factor 4 (PF4)/heparin complexes. No genome-wide evaluations have been performed to identify potential genetic influences on HIT. Here, we performed a genome-wide association study (GWAS) and candidate gene study using HIT cases and controls identified using electronic medical records (EMRs) coupled to a DNA biobank and attempted to replicate GWAS associations in an independent cohort. We subsequently investigated influences of GWAS-associated single nucleotide polymorphisms (SNPs) on PF4/heparin antibodies in non-heparin treated individuals. In a recessive model, we observed significant SNP associations (odds ratio [OR] 18.52; 95% confidence interval [CI] 6.33-54.23; p=3.18×10(-9)) with HIT near the T-Cell Death-Associated Gene 8 (TDAG8). These SNPs are in linkage disequilibrium with a missense TDAG8 SNP. TDAG8 SNPs trended toward an association with HIT in replication analysis (OR 5.71; 0.47-69.22; p=0.17), and the missense SNP was associated with PF4/heparin antibody levels and positive PF4/heparin antibodies in non-heparin treated patients (OR 3.09; 1.14-8.13; p=0.02). In the candidate gene study, SNPs at HLA-DRA were nominally associated with HIT (OR 0.25; 0.15-0.44; p=2.06×10(-6)). Further study of TDAG8 and HLA-DRA SNPs is warranted to assess their influence on the risk of developing HIT.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1160/TH14-08-0670DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4433536PMC
April 2015

Prospective evaluation of a rapid nanoparticle-based lateral flow immunoassay (STic Expert(®) HIT) for the diagnosis of heparin-induced thrombocytopenia.

Br J Haematol 2014 Sep 12;166(5):774-82. Epub 2014 May 12.

Haemostasis Laboratory and UMR CNRS 7292, Hôpital Trousseau and Université François Rabelais Tours, Tours, France.

A rapid lateral flow immunoassay (LFIA) (STic Expert(®) HIT), recently developed for the diagnosis of heparin-induced thrombocytopenia (HIT), was evaluated in a prospective multicentre cohort of 334 consecutive patients. The risk of HIT was estimated by the 4Ts score as low, intermediate and high in 28·7%, 61·7% and 9·6% of patients, respectively. Definite HIT was diagnosed in 40 patients (12·0%) with positive results on both enzyme-linked immunosorbent assay (Asserachrom(®) HPIA IgG) and serotonin release assay. The inter-reader reproducibility of results obtained was excellent (kappa ratio > 0·9). The negative predictive value of LFIA with plasma samples was 99·6% with a negative likelihood ratio (LR) of 0·03, and was comparable to those of the particle gel immunoassay (H/PF4-PaGIA(®) ) performed in 124 cases. Positive predictive value and positive LR were 44·4% and 5·87, respectively, and the results were similar for serum samples. The probability of HIT in intermediate risk patients decreased from 11·2% to 0·4% when the LFIA result was negative and increased to 42·5% when it was positive. In conclusion, the STic Expert(®) HIT combined with the 4Ts score is a reliable tool to rule out the diagnosis of HIT.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/bjh.12939DOI Listing
September 2014

Incidence of antibodies to protamine sulfate/heparin complexes incardiac surgery patients and impact on platelet activation and clinical outcome.

Thromb Haemost 2013 Jun 2;109(6):1141-7. Epub 2013 May 2.

Department of Hematology-Hemostasis, Trousseau Hospital, 37044 Tours Cedex, France.

A new ELISA (Zymutest HIA®), based on incubation of diluted plasma with protamine/heparin (PRT/H) complexes without and with platelet factor 4 (PF4) provided by a platelet lysate, was used to detect heparin-dependent antibodies in a cohort of 232 cardiac surgery (CS) patients and in 47 patients with heparin-induced thrombocytopenia (HIT). Significant binding of IgG/A/M to PRT/H complexes was demonstrated in 59 CS patients (25.4%), with similar absorbances whether platelet lysate was added to the plasma or not, and significant reactivity to PF4/H in 29 of them. Antibodies to PRT or heparin alone were present in 15 and two of these patients, respectively. Importantly, antibodies to PRT/H were detected in only three of the 47 HIT patients, who had also undergone recent CS. The Zymutest HIA® was positive in another 41 CS patients (17%), but only or mainly when their plasma was tested with platelet lysate, with significant levels of antibodies to PF4/H in 40 of them without detectable reactivity to PRT or heparin alone. Slight antibody binding to PRT/H complexes was also measured in six of these 41 patients. Therefore, a total of 35 CS patients exhibited dual antibody reactivity towards PRT/H and PF4/H complexes. Serotonin release assay performed with PRT alone was positive in 17 CS patients with antibodies to PRT/H, but all had normal platelet count evolution without thrombosis postoperatively. In conclusion, antibodies to PRT/H are frequently present in CS patients postoperatively (25.4%), and can activate platelets in vitro, but their clinical impact remains questionable.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1160/TH12-11-0844DOI Listing
June 2013

Polymorphisms of protein tyrosine phosphatase CD148 influence FcγRIIA-dependent platelet activation and the risk of heparin-induced thrombocytopenia.

Blood 2012 Aug 7;120(6):1309-16. Epub 2012 Jun 7.

Unité Mixte de Recherche Centre National de la Recherche Scientifique 7292 and Université François Rabelais, Tours, France.

Heparin-induced thrombocytopenia (HIT) is due primarily to IgG antibodies specific to platelet factor 4/heparin complexes (PF4/Hs) that activate platelets via FcγRIIA. CD148 is a protein tyrosine phosphatase that regulates Src kinases and collagen-induced platelet activation. Three polymorphisms affecting CD148 (Q276P, R326Q, and D872E) were studied in HIT patients and 2 control groups, with or without antibodies to PF4/Hs. Heterozygote status for CD148 276P or 326Q alleles was less frequent in HIT patients, suggesting a protective effect of these polymorphisms. Aggregation tests performed with collagen, HIT plasma, and monoclonal antibodies cross-linking FcγRIIA showed consistent hyporesponsiveness of platelets expressing the 276P/326Q alleles. In addition, platelets expressing the 276P/326Q alleles exhibited a greater sensitivity to the Src family kinases inhibitor dasatinib in response to collagen or ALB6 cross-linking FcγRIIA receptors. Moreover, the activatory phosphorylation of Src family kinases was considerably delayed as well as the phosphorylation of Linker for activation of T cells and phospholipase Cγ2, 2 major signaling proteins downstream from FcγRIIA. In conclusion, this study shows that CD148 polymorphisms affect platelet activation and probably exert a protective effect on the risk of HIT in patients with antibodies to PF4/Hs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1182/blood-2012-04-424044DOI Listing
August 2012

Interleukin-10 promoter microsatellite polymorphisms influence the immune response to heparin and the risk of heparin-induced thrombocytopenia.

Thromb Res 2012 Apr 10;129(4):465-9. Epub 2012 Jan 10.

Department of Hematology-Hemostasis, University Hospital of Tours, France.

Introduction: Heparin-induced thrombocytopenia (HIT) results from an atypical immune response with synthesis of IgG antibodies (Abs) to platelet factor 4/heparin complexes (PF4/H), and probably involves both B and T cells. We investigated whether 3 single nucleotide polymorphisms (SNPs), rs1800896 (-1082G/A), rs1800871 (-819C/T) and rs1800872 (-592C/A) and the polymorphic CA repeat microsatellites IL10R [5325CA(11_15)] and IL10G [8134CA(14_29)] are associated with the synthesis of Abs to PF4/heparin and HIT.

Materials And Methods: Eighty-two patients with definite HIT and two control groups were studied. The first control group (Ab(neg)) consisted of 85 patients without Abs to PF4/heparin after cardiopulmonary bypass (CPB). The second control group (Ab(pos)) consisted of 84 patients who had developed significant levels of PF4-specific antibodies after CPB, but without HIT.

Results: Allele frequencies of the 3 SNPs were similar in HIT patients and controls. Fourteen alleles in IL10G (G16 to G29) and 3 alleles in IL10R (R13 to R15) were defined. The short G20 allele of IL10G was more frequent in Ab(neg) patients (8.2%) than in Ab(pos) (2.9%) and HIT patients (3%). It thereby appeared to protect against developing Abs to PF4/heparin (OR 0.29; 95% CI [0.12-0.70], p=0.006). Combined haplotypes cH1/cH8 comprising the short G20 + R13 alleles were less frequent in HIT (OR 0.33; 95% CI [0.11-0.97], p=0.036), and levels of Abs to PF4 in Ab(pos) patients were lower in cH1/cH8 subjects (p=0.019).

Conclusion: These results suggest that IL10 promoter microsatellite polymorphisms might influence the immune response against PF4/heparin and the risk of HIT.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.thromres.2011.09.033DOI Listing
April 2012