We recently described tolerance induction with factor VIII/IX, cyclophosphamide, and high-dose intravenous IgG in hemophilia A or B patients with coagulation inhibitory antibodies. Circulating noninhibitory antibodies complexed with factor IX have been demonstrated in tolerant hemophilia B patients. Similar findings are now described in six tolerant hemophilia A patients. Complexes between fact...

Blood coagulation factors V and VIII are homologous proteins that have the domain organization A1-A2-B-A3-C1-C2. Upon thrombin activation, the B-domains of both molecules are released. Previous studies on factor VIII showed that the B-domain was not required for thrombin cleavage or activity. In contrast, deletion of the factor V B-domain (residues 709 to 1545) yielded a molecule with sevenfold...

Human factor VIII has been isolated from a high purity factor VIII concentrate by immunoaffinity chromatography and HPLC on Mono Q gel. Two fractions of factor VIII were obtained with a specific activity of approximately equal to 7000 units/mg. The major fraction contained eight peptide chains of 200, 180, 160, 150, 135, 130, 115, and 105 kDa plus one doublet chain of 80 kDa. The minor fraction...

The heterogeneity of human circulating serum. In one circulating anticoagulant, anticoagulants against antihemophilic light chain specificity could not be demonfactor (AHF, factor VIII) observed in seven strated with small amounts of antiserum, patients, both with and without classic and with larger amounts, only lambda hemophilia, was investigated by neutrallight chain specificity was revealed...

mammalians express several subclasses of the igg molecule. in human being there are four homologous igg subclasses, each of which is structurally unique and has different functions. quantification of igg subclasses is fundamental to clinical assessment and diagnosis of many diseases as such assessments depends on the availability of subclassspecific antibodies (abs), particularly monoclonal ant...

The heterogeneity of human circulating serum. In one circulating anticoagulant, anticoagulants against antihemophilic light chain specificity could not be demonfactor (AHF, factor VIII) observed in seven strated with small amounts of antiserum, patients, both with and without classic and with larger amounts, only lambda hemophilia, was investigated by neutrallight chain specificity was revealed...

Purified human factor VIII procoagulant protein (VIII:C) was treated with purified human activated protein C (APC) and the loss of VIII:C activity correlated with proteolysis of the VIII:C polypeptides. APC proteolyzed all VIII:C polypeptides with mol wt = 92,000 or greater, but not the doublet at mol wt = 79-80,000. These results and our previous thrombin activation studies of purified VIII:C,...

One of the major binding sites for factor VIII inhibitors is located within the A2 domain. In this study, phage display technology was used to isolate 2 human monoclonal antibodies, termed VK34 and VK41, directed toward the heavy chain of factor VIII. The V(H) domain of a single-chain variable domain antibody fragment (scFv) VK34 is encoded by germline gene segment DP-10. Epitope-mapping studie...

Previous studies using immunoneutralization techniques have shown that many factor VIII inhibitors are IgG antibodies of a single light chain type. We have investigated this apparent homogeneity by immunoneutralization assay and liquid isoelectric focusing of inhibitor fractions from five hemophiliacs and two nonhemophiliacs. By immunoneutralization assay, inhibitors from four hemophiliacs and ...