Impairment of quality of life in patients with antiphospholipid syndrome.

OBJECTIVES: Health-related quality of life (HRQoL) has not been fully explored in antiphospholipid syndrome (APS); therefore, we compared HRQoL between APS patients and the general population and assessed the impact of thromboembolic history. METHODS: HRQoL was measured in a multicentre cohort study by the Medical Outcomes Study Short-Form 36 (MOS-SF-36) questionnaire. HRQoL scores were compared to the French general population norms. Factors significantly associated with an impaired HRQoL were identified. RESULTS: A total of 115 patients with aPL and/or systemic lupus erythematosus (SLE) were included (mean age 42.7 ± 14.1 years old, 86 women). In 53 patients APS was diagnosed. Compared to general population norms, patients with APS had an impaired HRQoL. SLE-associated APS patients had the worst HRQoL scores (physical component summary (PCS)=40.8 ± 10.6; mental component summary (MCS)=40.6 ± 16.5) in comparison with SLE or aPL patients without thromboembolic history. In APS patients, history of arterial thrombosis significantly impaired HRQoL (PCS score: 42.2 ± 9.4 vs 49.2 ± 8.5; MCS score: 33.9 ± 13.7 vs 44.6 ± 10.3). CONCLUSION: Compared to the general population, APS patients experienced a lower HRQoL. In these patients, a history of arterial thrombosis significantly impaired HRQoL. Therefore, measurements of HRQoL should be included in APS patient management to assess the burden of the disease from a patient's perspective and to provide patients with the support they need.

Thrombin generation in antiphospholipid syndrome.

Our objective was to study acquired Activated Protein C (APC) resistance in patients with antiphospholipid antibodies (aPL) using a thrombin generation based assay. We compared patients with and without lupus (systemic lupus erythematosus, SLE). A parameter summarizing APC inhibition of thrombin generation with increasing APC concentrations (IC(50)-APC) was increased in all patient groups compared to controls: median values were 15.3 (interquartile range, IQR, 9.7 to 34.0) in patients with primary antiphospholipid syndrome (APS), 27.3 (IQR 23.5 to 43.5) in patients with SLE without APS, 64.1 (IQR 25.9 to 65.0) in patients with SLE/APS compared to 10.4 [IQR 8.5 to 15.8] in controls, respectively p = 0.003, p = 0.0001 and p = 0.0001. In conclusion, patients with SLE and primary APS displayed a hypercoagulable state characterized by APC resistance.

Increased risk for heart valve disease associated with antiphospholipid antibodies in patients with systemic lupus erythematosus: meta-analysis of echocardiographic studies.

BACKGROUND: Heart valve disease (HVD) is frequent in patients with systemic lupus erythematosus (SLE), and the role of antiphospholipid antibodies (aPL) is controversial. Thus, our objective was to estimate the risk of HVD, including Libman-Sacks endocarditis, associated with aPL in patients with SLE. METHODS AND RESULTS: Studies were selected if they investigated the association between aPL and HVD in SLE patients and if aPL-negative patients were included for comparison. Data sources were MEDLINE, Embase, Cochrane Library, hand search, contact with investigators, and reference lists of studies, without language restrictions. Data on study and patient characteristics, risk estimates, and study quality were independently extracted by 2 investigators. Pooled effect estimates were obtained by using the DerSimonian-Laird method. Of 234 identified abstracts, 23 primary studies (15 cross-sectional, 7 cohort, 1 case-control) met inclusion criteria, including 1656 SLE patients and 508 cases of HVD. Compared with SLE patients without aPL (n=988), the overall pooled odds ratios for HVD and Libman-Sacks endocarditis in aPL-positive patients (n=668) were 3.13 (95% confidence interval, 2.31 to 4.24) and 3.51 (95% confidence interval, 1.93 to 6.38), respectively. The risk of HVD depending on aPL subtypes was the highest for lupus anticoagulant at 5.88 (95% confidence interval, 2.92 to 11.84) and IgG anticardiolipin antibodies at 5.63 (95% confidence interval, 3.53 to 8.97). CONCLUSIONS: Overall, the presence of aPL in SLE patients is significantly associated with an increased risk for HVD including Libman-Sacks endocarditis. The risk conferred by IgG anticardiolipin antibodies is as strong as by lupus anticoagulant. Systematic echocardiographic examinations in SLE patients with aPL should be performed.

An international multicentre-laboratory evaluation of a new assay to detect specifically lupus anticoagulants dependent on the presence of anti-beta2-glycoprotein autoantibodies.

BACKGROUND: Antiphospholipid syndrome (APS) is diagnosed by the simultaneous presence of vascular thrombosis and/or pregnancy morbidity and detection of antiphospholipid antibodies in plasma. OBJECTIVES: We have shown that prolongation of clotting time by anti-beta2-glycoprotein I (beta2GPI) antibodies correlates better with thrombosis than a positive classic lupus anticoagulant (LAC) assay in a single center study. To confirm or falsify this finding we have conducted a multicenter study. METHODS AND RESULTS: In 325 LAC-positive samples, we found that the beta2GPI-dependent LAC correlated 2.0 times better with thrombosis than the classic LAC assay. Although significant, this was a minimal improvement compared with the 'classic' LAC. It was published that calcium influences the behavior of anti-beta2GPI antibodies in coagulation assays. To investigate whether calcium plays a role in the present study, we divided the patient population into two groups: (i) blood was collected in 0.109 m sodium citrate and (ii) blood was drawn in 0.129 m sodium citrate as anticoagulant. We found that a positive result with the beta2GPI-dependent LAC assay correlated better with thrombosis [odds ratio (OR): 3.3, 95% confidence interval (CI) 1.9-5.8] when 0.109 m sodium citrate was used compared with 0.129 m sodium citrate (OR: 0.4, 95% CI 0.1-1.1). CONCLUSION: We were able to confirm in an international multicenter study that a positive result in a beta2GPI-dependent LAC assay correlates better with thrombosis than the classic LAC assay, but that the assay needs further study as it is sensitive to external factors such as the sodium citrate concentration used as anticoagulant in the test sample.

Standardisation of thrombin generation test--which reference plasma for TGT? An international multicentre study.

We have previously shown that standardisation and normalization of results improve the intercentre variability of the calibrated automated thrombin generation test (TGT). We suspected that the source of reference plasma (RP) might be a contributing factor to variability and compared 5 commercial RP and a RP provided by the NIBSC, in an international, multicentre study. The detailed composition of the 6 tested plasma samples was determined in the Haemostasis Laboratory in Lyon. The lot to lot consistency, intra-assay, inter-assay variability were calculated for all tested plasmas. The RP and 3 plasma samples (a normal control, a hypocoagulable and a hypercoagulable plasmas) were tested over 6 days, in 5 European centres. Results were normalised against each of the tested RP and intercentre variability of results was compared. All laboratories used the same reagents. Before normalization, the inter-centre variability was 19.8 to 27.3%. After normalization, we observed a significantly improved inter-laboratory variation with all tested RP, despite differences between them. These results clearly demonstrate that the inter-centre variability of TGT can be significantly reduced by using a reference plasma normalization, and that certain RP have a better capacity to reduce this variability than others.

Nonbacterial purpura fulminans and severe autoimmune acquired protein S deficiency associated with human herpesvirus-6 active replication.

Nonbacterial purpura fulminans (PF) is rare, usually follows viral infection in young children, and is characterized by specific coagulation disorders, requiring specific therapy. Following a transient rash, a 2-year-old previously healthy girl developed PF without haemodynamic impairment. Laboratory data revealed disseminated intravascular coagulation and a severe transient protein S deficiency. Antiprotein S autoantibodies and active human herpesvirus-6 (HHV6) replication were demonstrated. Purpuric skin lesions spread very rapidly despite broad-spectrum antibiotics and right leg amputation. Plasmapheresis and intravenous immunoglobulins gave complete clinical recovery and normalization of protein S level within 10 days, with progressive clearance of antiprotein S autoantibodies. Transient severe protein S deficiencies have previously been reported in patients with nonbacterial PF, usually after varicella infection. This is the first documented case of PF after HHV6 infection.

Mild hemophilia A with factor VIII assay discrepancy: using thrombin generation assay to assess the bleeding phenotype.

INTRODUCTION: In some patients with mild hemophilia A, there are discrepancies between 1-stage (1-st) and 2-stage (2-st) factor VIII (FVIII) clotting assays, and also chromogenic assays for FVIII activity (FVIII:C). We examined whether thrombography could provide a better evaluation of the hemostatic status of these patients. METHODS: Two families with such discrepancies and markedly contrasting clinical histories were studied. Family X had no serious bleedings, in contrast to family Y. Sixty-one moderate/mild hemophiliacs without discrepancy and 15 healthy subjects served as controls. Calibrated automated thrombography was performed with platelet-rich plasma after one freeze-thawing cycle and low tissue factor concentration. RESULTS: The chromogenic FVIII:C levels were higher (0.90 +/- 0.15 and 0.47 +/- 0.13 IU mL(-1)) than the 1-st clotting ones (0.14 +/- 0.05 and 0.10 +/- 0.05 IU mL(-1)) in family X and Y, respectively (P < 0.001). Mean endogenous thrombin potential (ETP) was 1579 +/- 359 nM min(-1) and 1060 +/- 450 for healthy controls and hemophilic controls, respectively. For members of family X, the ETP values were 1188, 1317 and 2277 nM min(-1), whereas for those of family Y they ranged from 447 to 1122 nM min(-1). Two novel missense point mutations were evidenced: p.Ile369Thr in family X and p.Phe2127Ser in family Y. In family X, we postulate that the mutation is responsible for a delayed but non-deleterious FVIII activation. CONCLUSIONS: Our results suggest that the hemostatic phenotype assessed by thrombography may be clinically relevant in moderate/mild hemophilic patients with discrepant FVIII:C results.

Anti-protein S antibodies following a varicella infection: detection, characterization and influence on thrombin generation.

Postinfectious purpura fulminans is a rare disease. Varicella is one of the precipitating conditions and we recently observed such a case. The 4-year-old child was found to have a severe transient protein S deficiency. By enzyme-linked immunosorbent assay and surface plasmon resonance we first demonstrated that anti-protein S antibodies were present and also transient. Next we characterized the epitopes against which these antibodies were directed and found that they predominantly recognized the N-terminal part of protein S. Finally we showed by thrombography a transient dramatic hypercoagulable state as a result of thrombin being unregulated by the dynamic protein C inhibitory system: in vitro thrombin generation, in response to a low concentration of tissue factor, was almost insensitive to activated protein C up to 25 nmol L(-1) on day 4 while it was normally sensitive on day 42. For the first time, we demonstrated a temporal relationship between protein S deficiency, antibodies to protein S and hypercoagulability, thus supporting the pathogenic role of these antibodies.

Antistreptokinase platelet-activating antibodies are common and heterogeneous.

BACKGROUND: Platelet activation by antistreptokinase (SK) antibodies could impair the clinical effect of SK administration. OBJECTIVE: To better describe anti-SK antibodies with particular emphasis on procoagulant activities as a result of platelet activation. PATIENTS AND METHODS: Sera were collected from 146 patients with coronary artery disease: non-SK-treated, 95 from mainland France, 31 from French Polynesia; 20 patients from mainland in year 2 after SK treatment. Serum-induced SK-dependent platelet activation resulting in procoagulant activities was assessed with washed platelets from five donors representative of the known patterns of reactivities to IgG. RESULTS: Concentrations (2-5252 microg mL(-1)) and fibrinolytic neutralization titres (< 10 to > 1280) were found in the expected wide range and correlated (rho = 0.66, P < 0.0001). Platelet activation was detected with 145 samples, but varied in intensity and pattern (depending on the donors), although there was no systematic hierarchy; it was presumably due to IgG (inhibited by an IgG Fc receptor-blocking antibody and recovered in the IgG fraction) and only partially affected by aspirin. Marked platelet activation could be detected in samples with concentration as low as 2 microg mL(-1), and/or no detectable neutralizing titers. The way of immunization to SK was not found to influence the functional profile of antibodies. CONCLUSION: Anti-SK platelet-activating antibodies are widespread, heterogeneous, poorly predictable on the basis of their antifibrinolytic effect and strong enough to trigger procoagulant activities. Their clinical relevance should be formally assessed, using patients' own platelets for detection owing to the variation of platelet reactivity.

The calibrated automated thrombogram (CAT): a universal routine test for hyper- and hypocoagulability.

By using a "slow" fluorogenic thrombin substrate and continuous comparison to a simultaneously run calibrator, thrombin generation can be monitored automatically, on line, in clotting PPP or PRP at a throughput of up to 100 samples per hour. The resulting "Thrombogram" in PPP measures hypocoagulability (haemophilias, oral anticoagulants, heparins (-likes), direct inhibitors) and hypercoagulabilities (AT deficiency, prothrombin hyperexpression, prot. C and S deficiency, factor V Leiden, oral contraceptives). In PRP it is diminished in thrombopathies, in von Willebrand disease, by antibodies blocking GPIIb-IIIa or GPIb, or by antiplatelet drugs like aspirin and clopidogrel. Lupus anticoagulant both retards and increases thrombin generation. The thrombogram thus appears to be a broad function test of the haemostatic-thrombotic mechanism of the blood.

Oxidation of beta2-glycoprotein I (beta2GPI) by the hydroxyl radical alters phospholipid binding and modulates recognition by anti-beta2GPI autoantibodies.

We investigated whether beta2-glycoprotein I (beta2GPI), the key antigen in the antiphospholipid syndrome, is susceptible to oxidative modifications by the hydroxyl radical (*OH) that may influence its lipid-binding and antigenic properties. The effects on human and bovine beta2GPI of *OH free radicals generated by gamma-radiolysis of water with 137Cs were studied. Radiolytic *OH caused a dose-dependent loss of tryptophan, production of dityrosine and carbonyl groups. dimerization and/or extensive aggregation of beta2GPI. It ensued a reduction in affinity binding to cardiolipin liposomes and loss of beta2GPI-dependent autoantibody binding to immobilized cardiolipin. Patient anti-beta2GPI antibodies (n = 20) segregated into two groups based on the effect in the beta2GPI-ELISA of beta2GPI pretreatment with *OH: enhancement (group A, n = 10) or suppression (group B, n = 10) of IgG binding. The avidities of group A antibodies for fluid-phase beta2GPI were low but increased in a dose-dependent manner upon beta2GPI irradiation, in relation to protein crosslinking. Distinguishing features of group B antibodies included higher avidities for fluid-phase beta2GPI that was no longer recognized after *OH treatment, and negative anticardiolipin tests suggesting epitope location near the phospholipid binding site. The *OH scavengers thiourea and mannitol efficiently protected against all above changes. Therefore, oxidative modifications of beta2GPI via *OH attack of susceptible amino acids alter phospholipid binding, and modulate recognition by autoantibodies depending on their epitope specificities. These findings may be of clinical relevance for the generation and/or reactivity of anti-beta2GPI antibodies.

Beta2-glycoprotein I binding to platelet microparticle membrane specifically reduces immunoreactivity of glycoproteins IIb/IIIa.

We have investigated beta2-glycoprotein I (beta2GPI) binding to platelet-derived microparticles (PMP) and its effect on GPIIb/IIIa. PMP were isolated from washed human platelets after stimulation with A23187, and analyzed by surface plasmon resonance spectroscopy. Beta2GPI as well as activated protein C (APC) or annexin V bound to PMP-coated sensorchips, demonstrating exposure of anionic phospholipids on immobilized PMP. Beta2GPI binding was impaired by calcium and occurred in a concentration-dependent manner with apparent k(on) = 2.6 x 10(4) M(-1) s(-1) and k(off) = 4.4 x 10(-3) s(-1), corresponding to a KD value of 1.7 x 10(-7) M. When analyzed by flow cytometry, the binding of certain mAbs specific for GPIIb and/or GPIIIa was reduced in the presence of beta2GPI but not of APC or annexin V, whereas the binding of anti-GPIb or anti-P-selectin mAbs, or of soluble fibrinogen remained unchanged. These results suggest a broad but specific influence of beta2GPI on GPIIb/IIIa immunoreactivity, and indicate that beta2GPI may act as a modulator of GPIIb/IIIa-dependent functions of PMP.

Further evidence for the presence of anti-protein S autoantibodies in patients with systemic lupus erythematosus.

Acquired protein S (PS) deficiency in systemic lupus erythematosus (SLE) has been previously reported, but its mechanism and its possible thrombotic role have not been established. The aim of our study was to provide further evidence for auto-immune PS deficiency in 27 Tunisian SLE patients, using PS-specific enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance technology (SPR). PS deficiencies for PS activity, free PS or total PS, respectively, were found in 19, 18 and 12 patients. A significant correlation (r= -0.475, P< 0.016) was found between free/total PS ratio and C4bBP levels, suggesting a role of inflammation in free PS deficiency. Immunoglobulin IgG antibodies to PS were detected in four patients by both ELISA and SPR, in six patients only by ELISA, and in two patients only by SPR. Signals for anti-PS IgG by ELISA and SPR were, however, significantly correlated (r = 0.549, P = 0.003). These results suggest that an auto-immune mechanism could account for low PS activity in patients with SLE. Auto-antibodies to PS may form immune complexes, inducing increased clearance of PS or interfering with the protein C-protein S system.

[Determination of polymorphonuclear neutrophil adhesion receptors. Effect of pre-analytic factors]. / Mesure des récepteurs d'adhérence du polynucléaire neutrophile. Influence des paramètres pré-analytiques.

UNLABELLED: Polymorphonuclear neutrophil (PMN) adherence receptors expression varies with leukocyte activation state. Their quantification need accurate and inter-laboratories reproducible methods, without artefactual activation. OBJECTIVE: The aim of this study was to study the influence of cell preparation on PMN adherence receptors expression. MATERIALS AND METHODS: It was proposed to quantify, using immunolabeling standard (QIFIKIT(R), Dako), surface expression of the main adherence receptors (L-selectin and B(2) integrins), from different preparations of PMN: total blood collected with EDTA, isolated PMN by density gradient Polymorphprep(TM) 1,113 (Nycomed Pharma) and formaldehyde fixed PMN. RESULTS: A decrease of all receptors was noted after isolation and fixation of PMN, in comparison with whole blood PMN analysis. These results differed from data previously reported since, in these studies, activated phenotypes (increased of B(2) integrins) were observed after isolation and fixation methods. CONCLUSION: The present study provides strong evidence that pre-analytical conditions are sources of biological variations and thus extreme care must be taken in the interpretation of results. It underlines the interest of consensual practices for these pre-analytic and analytic parameters in order to compare results in multicenter and longitudinal studies.

[Use of standard for quantitation of adhesion of polynuclear neutrophils by flow cytometry]. / Utilisation d'un calibrateur pour quantifier les récepteurs d'adhérence du polynucléaire neutrophile par cytométrie en flux.

Adherence receptors are essential for heterotypic (endothelial cell, platelet) polymorphonuclear neutrophil (PMN) interaction. Determination of their expression level give information about activation state and functionality of PMN. Use of flow cytometry associated with an immunolabeling standard, represented by beads coated by a determined amount of immunoglobulins (Qifikit, Dako), allows analysis of specific antibody binding capacity and gives information about antigen density. Using this methodology, the exploration of surface adherence receptors, L-selectin (CD62L) and b2-integrins (CD11a-c/CD18) from PMN unstimulated and incubated with pro-inflammatory stimuli, formyl-methionyl-leucyl-phenylalanine (fMLP) and tumor necrosis factor a (TNFa), allows, on the one hand, the establishment of basal expression values on resting PNN and on the other hand, the study of PNN reactivity. This method of quantification can be applied to clinical studies as adherence receptor deficiency syndromes or inflammatory, infectious and vascular diseases.

Monovalent binding of autoantibodies to beta2-glycoprotein I, detected using surface plasmon resonance at low antigen density.

The precise mechanism of interaction between autoantibodies and beta2-glycoprotein I (beta2GPI) and the experimental conditions to be used for their detection are still under debate. Until now, these interactions have been studied under static conditions. We have investigated the interactions of purified IgG from 25 lupus anticoagulant-positive patients with immobilized beta2GPI under flow conditions by real-time analysis based on surface plasmon resonance technology. Sensor chips were coated with purified human beta2GPI coupled to dextran via amino groups at low densities (1.4, 1.8 or 2. 4 ng beta2GPI/mm2). Four patients' IgG displayed efficient binding and had the highest so-called antiphospholipid IgG levels by enzyme-linked immunosorbent assay (ELISA) and the highest absorbance values in an anti- beta2GPI ELISA at a beta2GPI density reported to be around 12 ng/mm2. Binding of antibodies to the beta2GPI sensor chips proved to be dependent upon the IgG concentration and beta2GPI density and was inhibited by a rabbit antibody against beta2GPI. Similar association and dissociation profiles were observed for the four efficient binders. The fast rate of dissociation limited the binding of autoantibodies to beta2GPI and was highly suggestive of a monovalent association, confirmed by binding of Fab fragments under similar experimental conditions. In conclusion, monovalent binding of low-affinity antibodies to beta2GPI immobilized at a density as low as 1.8 ng/mm2 could be detected using surface plasmon resonance.