The Nijmegen Modification of the Bethesda Assay for Factor VIII:C Inhibitors: Improved Specificity and Reliability

Verbruggen, Bert; Nováková, I.R.O.; Wessels, H.; Boezeman, J.B.M.; Berg, Marijke van den; Mauser‐Bunschoten, Eveline P.

doi:10.1055/s-0038-1653759

Cited by 620 publications

(567 citation statements)

References 11 publications

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“…The inhibitory titers in immunized mice were determined by the Nijmegen modification of the Bethesda assay (41). Hemophilia A mice immunized via s.c. route resulted in mean inhibitory titer of 690±78 (S.E.…”

Section: Resultsmentioning

confidence: 99%

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Phosphatidylinositol Containing Lipidic Particles Reduces Immunogenicity and Catabolism of Factor VIII in Hemophilia A Mice

Peng

Straubinger

Balu‐Iyer

2010

AAPS J

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Abstract. Factor VIII (FVIII) is an important cofactor in blood coagulation cascade. It is a multidomain protein that consists of six domains, NH 2 -A1-A2-B-A3-C1-C2-COOH. The deficiency or dysfunction of FVIII causes hemophilia A, a life-threatening bleeding disorder. Replacement therapy using recombinant FVIII (rFVIII) is the first line of therapy, but a major clinical complication is the development of inhibitory antibodies that abrogate the pharmacological activity of the administered protein. FVIII binds to anionic phospholipids (PL), such as phosphatidylinositol (PI), via lipid binding region within the C2 domain of FVIII. This lipid binding site not only consists of immunodominant epitopes but is also involved in von Willebrand factor binding that protects FVIII from degradation in vivo. Thus, we hypothesize that FVIII-PL complex will influence immunogenicity and catabolism of FVIII. The biophysical studies showed that PI binding did not alter conformation of the protein but improved intrinsic stability as measured by thermal denaturation studies. ELISA studies confirmed the involvement of the C2 domain in binding to PI containing lipid particles. PI binding prolonged the in vivo circulation time and reduced catabolism of FVIII in hemophilia A mice. FVIII-PI complex reduced inhibitor development in hemophilia A mice following intravenous and subcutaneous administration. The data suggest that PI binding reduces catabolism and immunogenicity of FVIII and has potential to be a useful therapeutic approach for hemophilia A.

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Section: Resultsmentioning

confidence: 99%

“…Inhibitory antibody titers were measured by the Nijmegen modification of the Bethesda assay (27,41). This assay is a modification of the one-stage aPTT assay which measures the ability of FVIII antibodies to inhibit the biological activity of FVIII.…”

Section: Measurement Of Inhibitory Anti-fviii Antibody Titersmentioning

confidence: 99%

Phosphatidylinositol Containing Lipidic Particles Reduces Immunogenicity and Catabolism of Factor VIII in Hemophilia A Mice

Peng

Straubinger

Balu‐Iyer

2010

AAPS J

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“…All the participating Centres used the Bethesda method and had introduced the Nijmegen modification (Verbruggen et al, 1995) in the late 1990s. Eligible patients had to be tested for inhibitors at least every 3 months during the first 100 EDs, every 6 months up to 200 EDs and yearly afterwards.…”

Section: Inhibitor Detectionmentioning

confidence: 99%

Environmental risk factors for inhibitor development in children with haemophilia A: a case–control study

et al. 2005

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This case-control study investigated the interactions between genetic and environmental factors and inhibitor development in 108 children with haemophilia A exclusively treated with recombinant factor VIII (FVIII). Sixty patients with inhibitors were compared with 48 inhibitor-free controls. Family history of inhibitors and null mutations in the FVIII gene were more prevalent in cases than in controls (20% vs. 2%, P = 0.001 and 83% vs. 64%, P = 0.04, respectively). On the other hand, there was no difference between cases and controls for such putative risk factors of inhibitor development as amniocentesis/villocentesis, premature/caesarean birth, breast-feeding, treatment during infections/vaccinations, surgical procedures and central nervous system bleeding. A trend was found for an increased risk of inhibitor development in children first treated at a young age (< 11 months); however, this was not confirmed after adjusting for genetic factors. The implementation of prophylaxis was evaluated as a putative risk factor in a subgroup of 25 cases: seven who started prophylaxis prior to inhibitor development and 18 potentially eligible for prophylaxis because they were inhibitor-free up to the age of 35 months (i.e. the upper limit of the age range at prophylaxis onset in cases and the median age at prophylaxis onset in controls). Patients who started prophylaxis had a lower inhibitor risk than those treated on demand (adjusted odds ratio 0.2, 95% confidence interval 0.06-0.9). The protective effect on inhibitor development shown by prophylaxis may represent an additional advantage prompting its use in haemophilic children

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“…Since sphingosine 1-phosphate (Sph-1-P) is abundantly stored in platelets and released extracellularly upon stimulation and since vascular endothelial cells express the G protein-coupled Sph-1-P receptors S1Ps, it is important to study the effect of Sph-1-P on endothelial cells from the viewpoint of platelet-endothelial cell interaction [3]. In this study, we examined the effect of Sph-1-P, in comparison with the inflammatory cytokines, on adhesion molecule expression; Sph-1-P was previously reported to mediate the response elicited by TNF-a [4].…”

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confidence: 99%

Prophylactic and perioperative replacement therapy for acquired factor XIII deficiency

Lim

Moffat

Hayward

2004

Journal of Thrombosis and Haemostasis

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To cite this article: Lim W, Moffat K, Hayward CPM. Prophylactic and perioperative replacement therapy for acquired factor XIII deficiency. J Thromb Haemost 2004; 2: 1017-19. Acquired factor (F)XIII deficiency is a rare coagulation disorder with limited information on using laboratory assays to guide management. We encountered unique monitoring and therapeutic challenges while managing a 73-year-old man with acquired FXIII deficiency. He presented with an extensive leg hematoma after receiving low-molecular-weight heparin for a suspected calf vein thrombosis. Two years earlier, he had developed a leg hematoma while on warfarin, which was discontinued. His medical history included inactive rheumatoid arthritis, stable angina, and paroxysmal atrial fibrillation on amiodarone. There was no family or prior bleeding history. He had previously undergone tonsillectomy, cholecystectomy and dental extractions without incident. Coagulation tests indicated an isolated deficiency of FXIII, with no FXIII activity detectable by the urea clot solubility assay [1,2] , twice weekly). A portacath was placed for home replacement therapy. Amiodarone was discontinued due to concerns about a drug-induced FXIII inhibitor.Six months later, the patient developed increasing angina. Angiography revealed a 90% stenosis of the left anterior descending coronary artery and a single coronary artery bypass graft was recommended. His FXIII inhibitor titer remained low (< 2 BU) and preoperative FXIII survival studies confirmed accelerated FXIII clearance, with more rapid decay of FXIII activity compared with FXIIIA antigen (Fig. 1A). Bypass surgery was done using off-pump, beating heart surgery to minimize risks of a postoperative coagulopathy. Perioperatively, FXIII levels were monitored using the Berichrom assay, as no other rapid commercial assays were available. He was given 2500 U FXIII (42 U kg ) immediately before and after surgery, and again on postoperative days 1-3, 5-7 and 9, before resuming his usual prophylaxis (2500 U twice weekly), which normalized his FXIII activity during surgery and maintained levels above 0.40 U mL )1 for 7 days postoperatively (Fig. 1B). No abnormal bleeding occurred and he recovered fully without complications. Over the subsequent 38 months, his FXIII inhibitor has remained < 2 BU and he has been maintained on lower doses of FXIII prophylaxis and aspirin 80 mg daily, without further angina or serious bleeding.He had a few minor bleeds when his FXIII prophylaxis was reduced to the point that no predose FXIII activity was detectable by urea clot solubility assays, but this resolved when his prophylaxis was adjusted to provide residual FXIII activity (1750 U, 29 U kg )1 weekly).FXIII is important for stabilizing fibrin and making clots less susceptible to plasmin lysis [5][6][7]. Inhibitors arising from replacement therapy in congenital FXIII deficiency are rare, and inhibitors causing acquired FXIII deficiency are 10 times as rare as congenital FXIII deficiency [8]. Acquired FXIII deficiency has been report...

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The Nijmegen Modification of the Bethesda Assay for Factor VIII:C Inhibitors: Improved Specificity and Reliability

Cited by 620 publications

References 11 publications

Phosphatidylinositol Containing Lipidic Particles Reduces Immunogenicity and Catabolism of Factor VIII in Hemophilia A Mice

Phosphatidylinositol Containing Lipidic Particles Reduces Immunogenicity and Catabolism of Factor VIII in Hemophilia A Mice

Environmental risk factors for inhibitor development in children with haemophilia A: a case–control study

Prophylactic and perioperative replacement therapy for acquired factor XIII deficiency

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