Clotting factor concentrates for resistant haemophilia

The use of an activated factor IX complex (Autoplex) in the management of haemarthroses in haemophiliacs with antibodies to factor VIII

A new activated factor IX product (Autoplex) has been used for the treatment of 18 haemarthroses in three haemophiliac patients with antibodies to factor VIII and a history of high anamnestic response to challenge with factor VIII. Results were evaluated by assessing pain, tenderness, range of movement and girth at 8 and 24 hours. A score of 2 was given for improvement at 8 hours and 1 for improvement at 24 hours. The result was expressed as a percentage of the possible score. Nine episodes treated with less than 35 units of Autoplex/kg had a mean score of 52% and nine episodes treated with more than 35 units/kg had a mean score of 73%. When only the more severe group of bleeds was considered, an even more marked dose related response emerged. When the ratio of the percentage fall in the PT to the percentage fall in the KCCT was plotted against the outcome, a significant correlation emerged (r = 0.43; P = 0.02).

The dental management of patients with spontaneous acquired factor VIII inhibitors

The histories of two patients without hemophilia but with spontaneous acquired factor VIII inhibitors are reported. A protocol is suggested for the combined hematologic and dental management of such patients.

Human factor IX inhibitors: immunochemical characteristics and treatment with activated concentrate

Plasma was obtained from two patients with severe factor IX deficiency who had developed specific inhibitors of factor IX. Immunochemical characterization of the inhibitors by coagulation inhibitor neutralization assays and by immunoelectrophoretic methods demonstrated that both were IgG antibodies. One of the antibodies appeared to be monoclonal in origin with IgG subclass 4 heavy chains and lambda light chains. The other appeared to be oligoclonal and contained IgG subclass 1 and subclass 4 heavy chains and kappa and lambda light chains. One of the patients was treated with conventional, non-activated factor IX concentrate and with activated factor IX concentrate (Feiba) for repeated bleeding episodes. Administration of Feiba resulted in a progressive shortening of the kaolin cephalin clotting time and was followed by a good clinical response. Infusion of non-activated factor IX concentrate failed to induce clinical resolution of haemarthroses and had minimal effect on laboratory tests. The presence of circulating immune complexes could not be demonstrated in this patient.

Factor VIII inhibitors: a clinical overview

There is much evidence to indicate that inhibitors to Factor VIII in patients with classical hemophilia are the result of an immunological response to exposure to material (VIII:C or VIII:CAg) that is absent or present in reduced amounts in these patients. The inhibitor is an antibody that is usually restricted in immunochemical composition and in many instances contains predominantly or exclusively gamma G3 or gamma G4 heavy chains. Exposure to Factor VIII in many inhibitor patients leads to typical anamnestic responses with marked increases in the level of the inhibitor. The tendency to develop inhibitors and the clinical characteristics of the inhibitor may be affected by genetic factors, basal levels of Factor VIII:C and/or VIII:CAg, and the nature and amount of the "immunizing" material. Currently accepted therapeutic modalities are aimed primarily at the management of acute bleeding episodes.

Analysis of the procoagulant activities of factor IX concentrates

The Factor VIII content of Factor IX concentrates was investigated by agarose gel electrophoresis which removed the interfering effects of stabilisers and proteolytic enzyme inhibitors. Factor VIII coagulant activity (FVIII C) as measured by clotting and amidolytic methods correlated well with the distribution of FVIII coagulant antigen (FVIII CAg). The FVIIIC activity was apparently not entirely due to the presence of activated coagulation enzymes, since none of the enzymicity patterns observed with various chromogenic substrates correlated completely with the FVIII peak. However, some enzyme activity was detected in positions coincident with the margins of the FVIII peak; these activities may represent complexes of some of the FVIII with activated coagulation factors.

Problems in hemophilia therapy

At present, the future of patients with hemophilia A may be regarded with more optimism due to advances in diagnosis and management which have occurred in recent years. However, a number of problems are still unresolved and others are now emerging against this optimistic background. The development of an inhibitor specifically destroying factor VIII coagulant activity renders the management at best difficult. It has been recognized recently that multitransfused hemophiliacs have a high incidence of abnormal liver function tests, and there is preliminary evidence that these are the expression of chronic active liver disease. This review is focused on these pitfalls of hemophilia care and emphasizes the recent developments in these fields and their impact on the pattern of life of hemophiliacs.

The role of intensive plasma exchange in the prevention and management of haemorrhage in patients with inhibitors to factor VIII

A strategy for the prevention and management of haemorrhage in patients with inhibitors to factor VIII by intensive plasma exchange and human factor VIII infusion is described. The advantages and disadvantages of this approach are discussed in the light of the authors' experience with the technique and the alternative methods of treatment described in the literature.

Case report: successful treatment of an idiopathic acquired factor VIII inhibitor with unusual features

A patient with an idiopathic acquired factor VIII inhibitor is described. Unusual features of this patient's illness were measurable factor VIII (4 to greater than 20%) despite the presence of inhibitor, and continued spontaneous bleeding despite these factor VIII levels. Successful treatment on both a short-term and a long-term basis--with neutralizing doses of human factor VIII concentrate and with chlorambucil, respectively--is reported. It is concluded that in patients with this type of inhibitor factor VIII, assays may not provide a reliable prediction of the potential for bleeding and that chlorambucil therapy warrants further study.

Acquired hemophilia, meningioma, and diphenylhydantoin therapy

A patient is reported in whom a meningioma of the lateral one-third of the sphenoid ridge was completely removed and long-term prophylaxis for seizures with diphenylhydantoin was prescribed. One and a half years later, a powerful inhibitor developed that specifically neutralized Factor VIII, the antihemophilic factor, and caused an acquired state of hemophilia. The 4-month hemorrhagic disorder was characterized initially by painless hematuria and later by intracerebral and extradural hematomas at the operative site of the previously excised meningioma. Despite the transfusion of massive quantities of concentrates of clotting factors, and the surgical evacuation of the recurrent hematomas on two occasions, the localized bleeding could not be staunched and the patient died. The types of inhibitors that cause acquired hemophilia and their modes of treatment are examined. Although it is possible that the Factor VIII inhibitor in this patient was induced by the meningioma, most previously reported tumors associated with acquired hemophilia have had an immunological basis. The most probable explanation for the acquired hemophilia in this patient was an inhibitor to Factor VIII from an autoantibody induced by the long-term use of diphenylhydantoin.

Human factor IX in animals: kinetics from isolated, radiolabelled protein and platelet destruction following crude concentrate infusions

Crude, concentrated and isolated, labelled human factor IX was prepared and infused into animals. Initially, two dogs with severe haemophilia B received both preparations and factor IX clotting activity and label survived well. Kinetic parameters fit a two-compartment open model. For 12 infusions of concentrates into normal baboons, clotting and antigen data again fit the model. Similar kinetics, with less variability, were found for nine infusions of [125I]factor IX. Radioactivity of the first post-infusion samples was > 90% precipitated in the double antibody system with an average of 84% of counts adsorbable to barium citrate. Compared to plasma, barium adsorbable counts gave a shorter t1/2 beta-elimination phase suggesting a small recirculating 125iodide pool. When [125I]factor IX was rechromatographed over heparin-agarose, variable amounts of altered, labelled protein were present; this species was more rapidly cleared from plasma post-infusion. Twelve infusions of crude concentrates into baboons were given to animals whose platelets had been labelled with 51Cr. Platelet counts as well as survival were then followed. For seven of these animals, mean counts decreased and the labelled platelets were destroyed, to an average of 21%, during the first 4 h post-infusion. Subsequent platelet survival was normal. Three infusions of gel-filtered, crude concentrates and two infusions of 'activated' commercial concentrates did not significantly alter platelet survival.

Hemophilia

The clinical manifestations of hemophilia depend upon both age and the severity of the factor VIII or IX deficiency. Hemophilia A and B cannot be differentiated on clinical grounds. Laboratory tests include platelet count, prothrombin time, partial thromboplastin time, and bleeding time.