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Development of neutralising antibodies (inhibitors) against factor VIII (FVIII) is a frequent and severe complication of replacement therapy in haemophilia A. Previous data from haemophilia A mouse model demonstrates that both CD32 inhibition and high doses of rhFVIII prevent the differentiation of FVIII-specific memory B cells (MBCs) into antibody secreting cells (ASCs). Here, cellular targets responsible for the suppression of ASC formation by means of CD32 inhibition and high dose of rhFVIII were analysed. We investigated apoptosis on FVIII-specific MBCs using a pan caspases inhibitor, and screened for defects in rhFVIII presentation by analysing T cell release of Th1- and Th2-cytokines in vitro. Although high dose of rhFVIII suppressed ASC formation, cytokine response was not affected. Upon re-stimulation of splenocytes with high dose of rhFVIII, prevention of apoptosis fully restored the FVIII-specific recall response. In contrast, genetic deletion or inhibition of CD32 significantly altered Th1- and Th2-response. CD32 blockade and inhibition of apoptosis resulted in a partial rescue of FVIII-specific ASCs. Normal cytokine secretion could not be restored. In conclusion, suppression of FVIII-specific recall response by CD32 and high doses of rhFVIII is mediated by distinct mechanisms. High dose of rhFVIII induces apoptosis in FVIII-specific MBCs but does not influence FVIII-specific T cell response. CD32 blockade, however, may suppress the FVIII-specific recall response by two ways: i) increasing apoptosis of FVIII-specific MBCs and ii) disturbing FVIII-specific T cell response by modulating presentation of rhFVIII to CD4 + T cells in vitro.

Factor VII (FVII) deficiency is one of the two congenital coagulation disorders that was not discovered by the description of a new bleeding patient whose clotting pattern did not fit the blood coagulation knowledge of the time (the other is factor XIII deficiency). The existence of an additional factor capable of accelerating the conversion of prothrombin into thrombin was suspected before 1951, the year in which the first family with FVII deficiency was discovered. As several investigators were involved in the discovery of FVII deficiency from both sides of the Atlantic, several different names were tentatively suggested to define this entity, namely stable factor (in contrast with labile factor or FV), cothromboplastin, proconvertin, serum prothrombin conversion accelerator, prothrombin acceleration, and autoprothrombin I. The last term was proposed by those who denied the existence of this new entity, which was instead considered to be a derivate of prothrombin activation, namely autoprothrombin. The description of several families, from all over the world, of the same defect, however clearly demonstrated the singularity of the condition. Factor VII was then proposed to define this protein. In subsequent years, several variants were described with peculiar reactivity toward tissue thromboplastins of different origin. Molecular biology techniques demonstrated several gene mutations, usually missense mutations, often involving exon 8 of the FVII gene. Later studies dealt with the relation of FVII with tissue factor and activated FVII (FVIIa). The evaluation of circulating FVIIa was made possible by the use of a truncated form of tissue factor, which is only sensitive to FVIIa present in the circulation. The development of FVII concentrates, both plasma derived and recombinant, has facilitated therapeutic management of FVII-deficient patients. The use of FVIIa concentrates was noted to be associated with the occasional occurrence of thrombotic events, mainly venous. Total or partial liver transplants have been performed with success in these patients and have "cured" their deficiencies. Prenatal diagnosis has also been performed and recent research involves the development of inhibitors of FVII + tissue factor complex or of FVIIa. This approach, if successful, could provide another antithrombotic therapeutics tool. The story of FVII well summarizes the efforts of both theoretical and clinical approaches in the characterization of a coagulation disorder, that is, among the rare bleeding conditions, most frequently encountered in clinical practice., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Replacement therapy is currently used to prevent and treat bleeding episodes in coagulation factor deficiencies. However, structural differences between the endogenous and therapeutic proteins might increase the risk for immune complications. This study was aimed at identifying factor (F)VII variants resistant to inhibitory antibodies developed after treatment with recombinant activated factor VII (rFVIIa) in a FVII-deficient patient homozygous for the p.A354V-p.P464Hfs mutation, which predicts trace levels of an elongated FVII variant in plasma. We performed fluorescent bead-based binding, ELISA-based competition as well as fluorogenic functional (activated FX and thrombin generation) assays in plasma and with recombinant proteins. We found that antibodies displayed higher affinity for the active than for the zymogen FVII (half-maximal binding at 0.54 ± 0.04 and 0.78 ± 0.07 BU/ml, respectively), and inhibited the coagulation initiation phase with a second-order kinetics. Isotypic analysis showed a polyclonal response with a large predominance of IgG1. We hypothesised that structural differences in the carboxyl-terminus between the inherited FVII and the therapeutic molecules contributed to the immune response. Intriguingly, a naturally-occurring, poorly secreted and 5-residue truncated FVII (FVII-462X) escaped inhibition. Among a series of truncated rFVII molecules, we identified a well-secreted and catalytically competent variant (rFVII-464X) with reduced binding to antibodies (half-maximal binding at 0.198 ± 0.003 BU/ml) as compared to the rFVII-wt (0.032 ± 0.002 BU/ml), which led to a 40-time reduced inhibition in activated FX generation assays. Taken together our results provide a paradigmatic example of mutation-related inhibitory antibodies, strongly support the FVII carboxyl-terminus as their main target and identify inhibitor-resistant FVII variants.

The administration of recombinant activated factor VII (rFVIIa) by continuous infusion has provided a safe and convenient alternative to bolus injections in haemophiliacs with inhibitors, but it has only been reported in a single case with congenital factor VII (FVII) deficiency. The results of 12 consecutive surgical procedures in 7 patients with congenital FVII deficiency are reported here. rFVIIa was always given in continuous infusion,aiming at plasma FVII activity of 0.5 IU/mL. Treatment was given for 2 to 7 days with a mean total dose of 7.8 mg rFVIIa. Blood loss was as expected from the different types of procedures and the only thromboembolic complication was a superficial thrombophlebitis at the infusion site. This mode of substitution was therefore safe, effective and well tolerated.

From its original envisioned use in patients with hemophilia and inhibitors, recombinant factor VIIa has been increasingly used in a variety of non-hemophilia bleeding/hemorrhagic situations with great efficacy. Most of the reported work has been in adult patients. This paper sets out to review its use in the pediatric non-hemophilia patients and the varied conditions it has been tried and used. Most of the published literature has shown that this agent is efficacious, safe and can be used as an adjunctive measure in the achievement of hemostasis. However, most of the published work is mainly anecdotal, case reports or small series. Randomized trials in children are eagerly awaited.

Background: Hepatitis C virus (HCV) infected hemophiliacs respond at low rate to interferon (IFN) monotherapy., Aims: To assess efficacy of IFN and RBV in HIV negative hemophiliacs with chronic hepatitis C and identify early predictive factors of response., Methods: Twenty naive patients were treated with interferon and RBV for twelve months. Response was assessed by both serial ALT and HCV RNA levels., Results: Normalization of ALT with clearance of HCV RNA occurred in seven (35%) patients. Age and age at infection were the only features associated with a higher likelihood of response. In all responders the viral load had decreased by at least one log within two months of starting treatment., Conclusions: Combination of interferon and ribavirin is well tolerated by hemophiliacs who achieve similar sustained response rates to non-hemophiliacs. Quantitative assessment of viral load at two months of treatment is a useful method to identify non-responders at an early stage.

Factor VII deficiency is a rare autosomal bleeding disorder with a highly variable hemorrhagic predisposition. Severe bleeding, including hemarthroses, may be encountered when plasma factor VII levels are below 1%. Patients have prolonged prothrombin times, and the final diagnosis is established by quantitative factor VII assays. Some patients have true deficiencies, that is, very low factor VII activity and low factor VII antigen (cross-reacting material) levels (CRM-); others have normal antigen levels but low activity (CRM+). Still others have reduced antigen levels (CRMR). There is a rather poor correlation between clinical symptoms and factor VII activity levels in plasma. Treatment of these patients consists of fresh frozen plasma, prothrombin complex concentrates, or factor VII concentrates. Recombinant activated factor VII (rFVIIa) is a very useful alternative, and several patients have been treated successfully. Because of the short half-life of factor VIIa, repeated doses have to be administered, and continuous infusion may be even better. Antibodies to factor VII have been reported but seem to be rather rare. From the available data it appears that rFVIIa is a safe and effective treatment modality for patients with congenital factor VII deficiency.