Factor VIII, a protein cofactor involved in blood coagulation, functions in vitro on a phospholipid membrane surface to greatly increase the rate of factor X activation by factor IXa. Using gel filtration, rapid sedimentation, and resonance energy transfer we have studied the interaction of recombinant-derived human factor VIII with small and large unilamellar phospholipid vesicles composed of ...

Radiolabeled human Factor VIII was used to study its survival in normals and patients with classic hemophilia, and to study the heterogeneity of Factor VIII; Purified Factor VIII was radiolabeled with 125iodine (125I-VIII) without loss of its structural integrity. The survival of 125I-VIII was studied in six normals and six hemophiliacs of whom four of the hemophiliacs had received transfusions...

The proteolytic activation of highly purified, heterodimeric porcine factor VIII and factor VIII-von Willebrand factor complex by thrombin was compared at I 0.17, pH 7.0, 22 degrees C. During the activation of factor VIII, heavy-chain cleavage is necessary to activate the procoagulant function, whereas light-chain cleavage is required to dissociate factor VIII from von Willebrand factor. The ki...

The characteristics of the intact factor VIII/von Willebrand factor protein binding to human platelets was compared to 2-mercaptoethanol-treated factor VIII/von Willebrand factor protein and to fractions of plasma factor VIII/von Willebrand factor protein that elute after the void volume. These studies indicate that the factor VIII/von Willebrand factor protein larger size oligomers bind prefer...

Two patients with hemophilia A and antiquential antibody titers demonstrated no factor VIII antibodies were treated with change in antibody response in either infusions of factor VIII concentrates and patient when compared to previous studintravenous cyclophosphamide in an aties following factor VIII infusion alone. tempt to suppress the antibody response. These results are in contrast to the p...

Thrombin activation of factor VIII results in a marked, but transient, increase in factor VIII procoagulant activity. This proteolytic process has been examined by immobilizing factor VIII in a solid phase system using mouse monoclonal antibody specific for the factor VIII related antigen. These studies demonstrate that thrombin activation is the result of proteolytic cleavage from the factor V...

Recombinant-derived human Factor VIII was labeled intrinsically with [35S]methionine, and its binding to washed human platelets was studied. Binding measurements were performed by incubating Factor VIII and platelets for 15 min at room temperature in Tyrode's solution supplemented with Ca2+ (5.0 mM), 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (5.0 mM), 0.50% bovine serum albumin, and th...

The interaction of Factor VIII-von Willebrand Factor with phospholipid vesicles has been studied by using sucrose-density-gradient ultracentrifugation. When purified Factor VIII-von Willebrand Factor was run alone. Factor VIII activity and Factor VIIIR-Ag sedimented together to the lower half of the tube. Addition of phosphatidylserine/phosphatidylethanolamine vesicles at concentrations above 2...

The present study reports on the treatment of bleeding episodes and the natural history of factor VIII inhibitors in 4 patients with acquired haemophilia A postpartum. Low titre type II factor VIII inhibitors in 3 patients and high titre type I inhibitor in 1 patient became apparent immediately to 7 months after delivery. High dose human factor VIII concentrate substitution was effective in con...

The epitopes of four monoclonal antibodies against coagulation Factor VIII were mapped with the use of recombinant DNA techniques. Full-length Factor VIII cDNA and parts thereof were inserted into the vector pSP64, permitting transcription in vitro with the use of a promoter specific for SP6 RNA polymerase. Factor VIII DNA inserts were truncated from their 3'-ends by selective restriction-enzym...