1. Native plasma-derived FVIII/VWF complex has lower sensitivity to FVIII inhibitors than the combination of isolated FVIII and VWF proteins. Impact on Bethesda assay titration of FVIII inhibitors
- Author
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S Grancha, J. I. Jorquera, B Da Rocha-Souto, and M I Bravo
- Subjects
congenital, hereditary, and neonatal diseases and abnormalities ,animal diseases ,von Willebrand factor ,Hemophilia A ,Thrombin generation ,Bethesda assay ,law.invention ,Von Willebrand factor ,thrombin generation assay ,law ,Isoantibodies ,hemic and lymphatic diseases ,Medicine ,Humans ,Blood Coagulation ,Genetics (clinical) ,Factor VIII ,biology ,Blood Coagulation Factor Inhibitors ,business.industry ,Plasma derived ,Thrombin ,FVIII inhibitors ,Hematology ,General Medicine ,Molecular biology ,In vitro ,FVIII/VWF complex ,Titer ,Drug Combinations ,Kinetics ,Immunology ,Recombinant DNA ,biology.protein ,cardiovascular system ,Titration ,Original Article ,Blood Coagulation Tests ,Antibody ,business ,circulatory and respiratory physiology ,Protein Binding - Abstract
Sensitivity to FVIII inhibitors of the native plasma-derived (pd) FVIII/VWF complex vs. the complexes formed after exogenous FVIII infusion in the haemophilic patient has not been thoroughly studied. The role of VWF in the interaction of FVIII with inhibitors was studied in vitro using different combinations of VWF and FVIII concentrates. Normal plasma, pdFVIII/VWF and isolated FVIII (recombinant FVIII, B-domain deleted and pdFVIII) were used. Titre (BU) was kinetically determined (up to 2 h) in serial dilutions of inhibitor IgG (purified from a pool of plasmas with inhibitors) mixed with VWF and then incubated with the different FVIII. Inhibitor was also added to previously mixed VWF+FVIII. Residual FVIII:C was determined. TGA assays were performed with FVIII-deficient plasma spiked with the FVIII-VWF mixtures with/without an ESH-8 antibody. Inhibitor titres for plasma and pdFVIII/VWF were comparable at all time points. Titres for all concentrates of isolated FVIII were significantly higher than those for plasma or pdFVIII/VWF (1.4–1.9 fold) even after preincubation with VWF. At t = 0 h, titres for plasma or pdFVIII/VWF were unquantifiable, but were detectable for isolated FVIII (0.6–1.6 BU). In contrast to pdFVIII/VWF, the decrease in thrombin generation parameters by isolated FVIII in the presence of ESH-8 was significant (P
- Published
- 2014