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Background Anticardiolipin (aCL) and anti-β2 glycoprotein I (aβ2GPI) immunoglobulin A (IgA) antiphospholipid antibodies (aPL) have shown to associate with thrombosis and pregnancy morbidity. However, inclusion of IgA aPL in the classification criteria of the antiphospholipid syndrome (APS) has been debated. We investigated the value of aCL and aβ2GPI IgA aPL in the detection of thrombosis and pregnancy morbidity in addition to the current aPL panel for APS. Methods We included 1,068 patients from eight European medical centers: 259 thrombotic APS patients, 122 obstetric APS patients, 204 non-APS thrombosis patients, 33 non-APS obstetric patients, 60 APS patients with unspecified clinical manifestations, 196 patients with autoimmune diseases, and 194 controls. aCL and aβ2GPI IgG/M/A were detected with four commercial assays and lupus anticoagulant was determined by the local center. Results Positivity for IgA aPL was found in 17 to 26% of the patients with clinical manifestations of APS and in 6 to 13% of the control population. Both aCL and aβ2GPI IgA were significantly associated with thrombosis and pregnancy morbidity. Isolated IgA positivity was rare in patients with clinical manifestations of APS (0.3–5%) and not associated with thrombosis and/or pregnancy morbidity. Addition of IgA to the current criterion panel did not increase odds ratios for thrombosis nor pregnancy morbidity. Conclusion aCL and aβ2GPI IgA are associated with clinical manifestations of APS. However, isolated IgA positivity was rare and not associated with thrombosis or pregnancy morbidity. These data do not support testing for aCL and aβ2GPI IgA subsequent to conventional aPL assays in identifying patients with thrombosis or pregnancy morbidity.

Background The anti-phospholipid syndrome (APS) is characterized by thrombosis and/or pregnancy morbidity with persistent presence of anti-phospholipid antibodies (aPL). Laboratory criteria include aPL detection by coagulation tests for lupus anticoagulant (LAC) or solid phase assays measuring anti-β2 glycoprotein I (aβ2GPI) or anti-cardiolipin (aCL) immunoglobulin (Ig) G/IgM antibodies. External quality control programs illustrate that commercially available aPL assays produce variable results. Objective We aimed to investigate the agreement and diagnostic accuracy of solid phase assays. Materials and Methods In this multi-centre study, 1,168 patient samples were tested on one site for aCL and aβ2GPI IgG/IgM antibodies by four solid phase test systems. Samples included APS patients, controls and monoclonal antibodies (MoAB) against different epitopes of β2GPI. LAC was determined by the local centre. Results aCL IgM assays resulted in the most discrepancies (60%), while aCL IgG and aβ2GPI IgM assays resulted in lower discrepancies (36%), suggesting better agreement. Discrepant samples displayed lower median aPL titers. Dependent on the solid phase test system, odds ratios (ORs) for thrombosis and pregnancy morbidity ranged from 1.98 to 2.56 and 3.42 to 4.78, respectively. Three platforms showed lower sensitivity for MoAB directed against the glycine (Gly) 40-arginine (Arg) 43 epitope of domain I of β2GPI. Conclusion Poor agreement was observed between different commercially available aCL and aβ2GPI IgG/IgM assays, hampering uniformity in the identification of aPL-positive patients. Clinical association was globally concordant between solid phase test systems considering results of the four aPL together. An assay sensitive in detecting the MoAB against Gly40-Arg43 of domain I of β2GPI reached the highest OR for thrombosis.

SummaryThere is little knowledge regarding the in-vivo course of coagulation reactions in subjects with factor (F)V Leiden (G1691A, R506Q). The aim of the current study was to evaluate the effect of FV Leiden on coagulant reactions triggered by vascular injury. At the site of microvascular injury, prothrombin activation and FVa formation and inactivation have been evaluated in 16 apparently healthy subjects and 16 patients on long-term anticoagulation with acenocoumarol, with eight heterogenous carriers of FV Leiden in the healthy and in the anticoagulated group. Thrombin formation, measured by levels of thrombin-antithrombin complexes (TAT) and thrombin B-chain, proceeded at similar rates in the bleeding-time blood in carriers and non-carriers of FV Leiden. The onset and rate of FV activation did not differ significantly among the four groups. When healthy carriers of FV Leiden were compared to healthy non-carriers, the onset of FVa inactivation by activated protein C (APC) was delayed by 60 to 90 seconds (p=0.01). Anticoagulated individuals also showed the same pattern of FV Leiden associated differences in the time of occurrence of the 30 kD FVa heavy-chain fragment (p=0.021). Our results indicate that when blood clotting is triggered by microvascular injury, the heterozygous expression of FV Leiden has no effect on thrombin generation in healthy or coumadintreated subjects. Inactivation of FVa by theAPC mechanism is attenuated significantly in carriers of FV Leiden but the magnitude of this effect is smaller than that observed in most purified systems.

SummaryIndividual variability in response to clopidogrel is known but its mechanism is poorly understood. We examined the relationship between glycoprotein IIIa polymorphism PlA1/A2 and anti-thrombotic actions of clopidogrel. Clopidogrel (75 mg/d; 2 weeks) was administered to 48 normolipemic patients with coronary artery disease. Bleeding time, thrombin generation at the site of microvascular injury, platelet function under high shear, using PFA-100 with ADP cartridge, and platelet surface activation markers (P-selectin and fibrinogen binding sites on GPIIb/IIIa complex detected by PAC-1 antibody), were studied both before and after clopidogrel treatment. Both unstimulated and low-dose (0.02 μM and 1 μM) in vitro ADP-stimulated platelets were examined. GP IIIa polymorphism was assessed by polymerase chain reaction and restriction fragment length polymorphism analysis. We identified 32 PlA1/A1 homozygotes, 15 PlA1/A2 heterozygotes and one PlA2/A2 homozygote. Clopidogrel significantly prolonged bleeding time in all subjects, but this effect was greater in PlA2 carriers (p

Arterial and venous thrombosis and prothrombotic fibrin clot phenotype in a Polish family with type 1 antithrombin deficiency (antithrombin Krakow)

SummaryAspirin and statins are beneficial in coronary heart disease across a broad range of cholesterol levels. We assessed the effects of low-dose aspirin (75 mg daily) on thrombin generation in patients with coronary heart disease and average blood cholesterol levels. We also investigated whether in patients with borderline-high cholesterol level who have been already taking aspirin, additional treatment with simvastatin would affect thrombin generation.Seven-day treatment with low-dose aspirin decreased thrombin generation ex vivo only in patients with total cholesterol 5.2 mmol/L. In patients with higher cholesterol levels aspirin had no effect. In these patients, already taking low-dose aspirin, additional three-month simvastatin treatment resulted in a reduction of thrombin generation. This demonstrates that low-dose aspirin depresses thrombin generation only in subjects with desirable blood cholesterol levels, while in others, with borderline-high cholesterol, thrombin formation is being reduced following the addition of simvastatin.

SummaryWe tested the hypothesis that plasma fibrin clot structure/function is unfavourably altered in patients with antiphospholipid syndrome (APS). Ex vivo plasma clot permeability, turbidity and susceptibility to lysis were determined in 126 consecutive patients with APS enrolled five months or more since thrombotic event vs 105 controls. Patients with both primary and secondary APS were characterised by 11% lower clot permeability (p

SummaryInhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMGCoA) reductase, statins, have been demonstrated to reduce cardiovascular morbidity and mortality in patients with a wide range of cholesterol levels. Numerous cholesterol-independent effects of statins that may limit atherosclerosis are probably related to inhibition of the geranylgeranylation of GTP-binding intracellular signaling proteins and involve: improved vasoreactivity, mostly through increased NO bioavailability; decreased expression of proinflammatory cytokines (interleukin-6, interleukin-1β, tumor necrosis factor α), C-reactive protein, chemokines, matrix metalloproteinases, and tissue factor with the subsequent inhibition of thrombin generation; reduced platelet activity; increased thrombomodulin expression; enhanced fibrinolysis, regulation of angiogenesis and immunomodulation. However, the clinical relevance of multiple protective effects induced by statins has not been clarified yet.

SummaryThrombosis plays a major role in the development of atherosclerosis and its acute vascular complications. Epidemiological studies have shown that elevated levels of plasma fibrinogen are associated with an increased risk of coronary heart disease (CHD). It is not clear whether this association is linked to hemostatic functions of fibrinogen which serves as a substrate for thrombin. Generation of thrombin in vivo can be evaluated by measurement of its specific markers in plasma, i.e. thrombin-antithrombin III complex (TAT) and prothrombin fragment 1+2 (F1+2). We determined plasma levels of TAT and F1+2 in a population sample of southeastern Poland and evaluated relations of these markers with plasma fibrinogen, factor VII coagulant activity (FVIIc), and other known CHD risk factors. The population studied consisted of 215 men and 251 women, aged 43-75 years. Final analysis was performed on 195 men and 222 women.The distribution of plasma TAT and F1+2 concentrations were highly skewed with the higher median values for women than for men. Log values of TAT correlated with log values of F1+2 in men (r = 0.27, p The association of plasma fibrinogen and FVIIc with thrombin generation markers points to an important role of the hemostatic system in the pathogenesis of atherosclerosis and coronary heart disease in humans.