Adrienne Kerényi

Antiphospholipid antibodies in acute coronary syndrome

Antiphospholipid (aPL) antibodies entailing anticardiolipin (aCL) and anti-β2 glycoprotein I (anti-β2 GPI) antibodies may be involved in a number of vascular diseases including coronary artery diseases (CAD) or stroke. Here we assessed the presence of aPL antibodies in acute coronary syndrome (ACS). The frequency of anti-β2 GPI antibodies was significantly higher (14.4%) in ACS in comparison to control healthy subjects (2%). In addition, serum concentrations of anti-β2 GPI antibodies were also increased in ACS. Anti-β2 GPI antibodies of the IgA isotype might be the most relevant for the onset and outcome of ACS. Regarding subclasses of ACS, anti-β2 GPI IgA antibodies were elevated in unstable angina (UA) and myocardial infarction with ST elevation (STEMI), but not in myocardial infarction without ST elevation (NSTEMI). The involvement of anti-β2 GPI antibodies in ACS was more pronounced in men than women, and in younger rather than older patients. Finally, anti-β2 GPI antibodies in ACS were associated with previous stroke, but not with hypertension or previous myocardial infarction. Thus, anti-β2 GPI antibodies may be involved in the thrombotic events underlying ACS.

Severe bleeding complications caused by an autoantibody against the B subunit of plasma factor XIII: a novel form of acquired factor XIII deficiency

Acquired factor XIII (FXIII) deficiency due to autoantibody against FXIII is a very rare severe hemorrhagic diathesis. Antibodies directed against the A subunit of FXIII, which interfere with different functions of FXIII, have been described. Here, for the first time, we report an autoantibody against the B subunit of FXIII (FXIII-B) that caused life-threatening bleeding in a patient with systemic lupus erythematosus. FXIII activity, FXIII-A(2)B(2) complex, and individual FXIII subunits were undetectable in the plasma, whereas platelet FXIII activity and antigen were normal. Neither FXIII activation nor its activity was inhibited by the antibody, which bound to structural epitope(s) on both free and complexed FXIII-B. The autoantibody highly accelerated the elimination of FXIII from the circulation. FXIII supplementation combined with immunosuppressive therapy, plasmapheresis, immunoglobulin, and anti-CD20 treatment resulted in the patients recovery. FXIII levels returned to around 20% at discharge and after gradual increase the levels stabilized above 50%.

Comparison of PFA-100 Closure Time and Template Bleeding Time of Patients with Inherited Disorders Causing Defective Platelet Function

MINI REPORT Comparison of PFA-100 Closure Time and Template Bleeding Time of Patients with Inherited Disorders Causing Defective Platelet Function Adrienne Kerenyi1, Agota Schlammadinger2, Eva Ajzner1, Istvan Szegedi3, Csongor Kiss3, Zoltan Pap4, Zoltan Boda2 and Laszlo Muszbek1 1Department of Clinical Biochemistry and Molecular Pathology, 2Second Department of Medicine, 3Department of Pediatrics, University Medical School of Debrecen, Debrecen, 4City Health Service, Ophthalmology Unit, Debrecen, Hungary.

Potential Therapeutic Targeting of Platelet-Mediated Cellular Interactions in Atherosclerosis and Inflammation

Cellular interactions among platelets, leukocytes and endothelial cells are considered as a major cause of inflammation and atherosclerosis in many diseases. Via exposed surface receptors and released soluble substances, activated platelets play a crucial role in the initiation of inflammatory processes, resulting in endothelial injury and leading to formation of atherosclerotic plaque with possible thrombotic complications. Classic anti-platelet treatments (e.g. cyclooxygenase inhibitor or ADP-receptor antagonist) have favorable effects in patients with vascular diseases, but they also have several limitations such as increased bleeding risk or non-responsiveness. Thus, the need and opportunities for developing novel therapeutic inhibitors for platelet-mediated events are obvious. Animal and (pre)clinical human studies have suggested that some recently produced specific antagonists of P-selectin from α-granules, as well as its main ligand/receptor P-selectin Glycoprotein Ligand-1, the two major platelet chemokines CXCL4 and CCL5, as well as CD40L, may be considered potential new candidates in the treatment of atherogenesis and inflammation. In this review, we summarize the pathophysiological roles of these effectors in platelet activation and acute or chronic inflammation, and discuss the latest findings on promising antagonistic agents in basic and clinical studies in the prevention of platelet-mediated cellular interactions.

The superiority of anti-FXa assay over anti-FIIa assay in detecting heparin-binding site antithrombin deficiency.

OBJECTIVES Antithrombin is a progressive inhibitor of active factor X (FXa) and thrombin (FIIa). Its effect is 500- to 1,000-fold accelerated by heparin or heparan sulfate. Heterozygous type I (quantitative) and most type II (qualitative) antithrombin deficiencies highly increase the risk of venous thromboembolism (VTE), while homozygous mutations are lethal. The functional defect affecting the heparin-binding site confers moderate risk of VTE to heterozygous and high risk of VTE to homozygous individuals. METHODS Antithrombin activity assays based on the inhibition of FIIa and FXa were compared for their efficiency in detecting heparin-binding site defects. RESULTS With a single exception, in heterozygotes for heparin-binding site defects (n = 20), anti-FIIa activities remained in the reference interval, while anti-FXa activities were uniformly decreased. In individuals who were homozygous for heparin-binding site mutations (n = 9), anti-FIIa activities were in the range of 48% to 80%; the range of anti-FXa activities was 9% to 25%. Anti-FIIa and anti-FXa activities in type I deficiencies and type II pleiotropic deficiency did not differ significantly. CONCLUSIONS Anti-FXa antithrombin assay is recommended as a first-line test to detect type II heparin-binding site antithrombin deficiency.

Rapid-onset heparin-induced thrombocytopenia without previous heparin exposure.

Heparin-induced thrombocytopenia (HIT) is one of the most common immune-mediated drug reactions. Immunoglobulin G-type antibodies against platelet factor 4(PF4)/heparin complexes are known to play a key role in the pathogenesis of HIT. Rapid-onset HIT is caused by the presence of circulating HIT antibodies at the time of heparin readministration. These antibodies are generally resulted from a recent immunizing exposure to heparin. Here we report a case of rapid-onset HIT developed after a septicemia without previous heparin exposure. The diagnosis of HIT as well as the presence of platelet activating and heparin-dependent antibodies was confirmed by ELISA and flow cytometric functional assays. Our case report reinforces that rapid-onset HIT cannot be excluded only based on the absence of previous heparin exposure. In addition, it may support the new theory of pre-immunization by PF4-coated bacteria in the pathomechanism of HIT. We also call the attention that venous limb gangrene can be rarely associated with HIT and thrombosis even in the absence of coumarin therapy. Furthermore, transient presence of anti-phospholipid antibodies can cause a differential diagnostic problem in the cases of HIT.

Follow-up of thrombin generation after prostate cancer surgery: global test for increased hypercoagulability.

Recent studies provided evidence that evaluation of thrombin generation identifies patients at thrombotic risk. Thrombin generation has a central role in hemorrhage control and vascular occlusion and its measurement provides new metrics of these processes providing sufficient evaluation of an individual’s hemostatic competence and response to anticoagulant therapy. The objective of the study is to assess a new measure of hypercoagulability that predisposes to venous thromboembolism in the postoperative period after radical prostatectomy. Pre- (day-1) and postoperative (hour 1, day 6, month 1 and 10) blood samples of 24 patients were tested for plasma thrombin generation (peak thrombin), routine hematology and hemostasis. Patients received low molecular weight heparin for thromboprophylaxis. Peak thrombin levels were higher in patients compared to controls at baseline (p<0.001), and elevated further in the early postoperative period (p<0.001). Longer general anesthesia and high body mass index were associated with increased thrombin generation after surgery (p = 0.024 and p = 0.040). D dimer and fibrinogen levels were higher after radical prostatectomy (p = 0.001 and p<0.001). Conventional clotting tests remained within the reference range. Our study contributed to the cognition of the hypercoagulable state in cancer patients undergoing pelvic surgery and revealed the course of thrombin generation after radical prostatectomy. Whilst it is unsurprising that thrombin generation increases after tissue trauma, further evaluation of this condition during the postoperative period would lead urologists to an international and well-supported consensus regarding thromboprophylaxis in order to provide better clinical outcome. Considering the routine evaluation of procoagulant activity and extending prophylactic anticoagulant therapy accordingly may potentially prevent late thrombotic events.

Management and outcome of pregnancies in women with antithrombin deficiency: a single-center experience and review of literature.

Women with antithrombin (AT) deficiency have an increased risk for pregnancy-associated venous thromboembolism (VTE) and adverse pregnancy outcome. AT deficiency is a rare thrombophilia with heterogeneous genetic background. Owing to the few cases reported in the literature, management strategies of pregnancy with AT deficiency are inconsistent. Our aim was to examine the type of the genetic defect, management, maternal, and pregnancy outcome in patients with hereditary AT deficiency. Five expectant mothers with AT deficiency were followed in our center to evaluate thrombotic events, and maternal and pregnancy outcomes. AT gene sequencing was performed in all cases, and levels of AT and anti-activated factor X were regularly measured to guide the risk-adopted anticoagulant prophylaxis. Three mothers had homozygous type II heparin-binding site mutations and two had heterozygous type I mutations of the gene encoding AT. Two women had additional factor V Leiden heterozygous mutations. Three maternal VTEs – four healthy newborns and five pregnancy losses – were observed. The risk of patients to VTE and adverse pregnancy outcome was found to associate with the homozygous type II heparin-binding site mutation of the AT gene. High risk of maternal VTE and frequent pregnancy complications were observed to associate with AT deficiency. Our results support the need of individualized, risk-adopted anticoagulant therapy in patients with AT deficiency.

A novel homozygous mutation (1619delC) in GPIIb gene associated with Glanzmann thrombasthenia, the decay of GPIIb-mRNA and the synthesis of a truncated GPIIb unable to form complex with GPIIIa

The absence of agonist-induced platelet aggregation and the lack of fibrinogen receptor (GPIIb/IIIa) on the platelet surface demonstrated that the severe hemorrhagic complications of a child of Romany descent were caused by Glanzmann thrombasthenia. DNA sequencing revealed a novel homozygous deletion of a cytosine (1619delC) in the GPIIb gene causing a frameshift and predicting a novel stop codon at position 533 following 24 altered amino acids. Both parents possessed the same deletion in heterozygous form. The amount of GPIIb mRNA in the patients platelets was 0.06% of the amount measured in control platelets. Neither GPIIb nor its truncated form could be detected in the platelets of the patient by Western blotting, while a small amount of GPIIIa was demonstrated. Quantitative flowcytometric analysis showed an elevated number of vitronectin receptors, a component of which is GPIIIa, on the patients platelets. The surface expression of vitronectin receptor on thrombasthenic, but not on normal platelets was further increased by activation with thrombin receptor agonist peptide. BHK cells transfected with wild type GPIIIa andmutated GPIIb failed to express any mature GPIIb or pro-GPIIb. Immunoprecipitation with a polyclonal antibody recognizing both GPIIb and GPIIIa recovered a 60 kDa truncated form of GPIIb. This band was absent when immunoprecipitation was carried out with an antibody recognizing GPIIIa, suggesting that the truncated protein, lacking calf-1, calf-2 domains and major part of the thigh domain, is unable to form complex with GPIIIa.

The use of recombinant factor XIII in a major bleeding episode of a patient with congenital factor XIII deficiency - the first experience

U. Clinical utility gene card for: Glanzmann thrombasthenia. Eur J Hum Genet 2012; 20: 1102. 5 Fiore M, Firah N, Pillois X, Nurden P, Heilig R, Nurden AT. Natural history of platelet antibody formation against alphaIIbbeta3 in a French cohort of Glanzmann thrombasthenia patients. Haemophilia 2012; 18: e201–9. 6 Seligsohn U. Treatment of inherited platelet disorders. Haemophilia 2012; 18(Suppl. 4): 161–5. 7 Hedner U, Erhardtsen E. Potential role of recombinant factor VIIa as a hemostatic agent. Clin Adv Hematol Oncol 2003; 1: 112–9.