Incidence of factor IX inhibitor development in severe haemophilia B patients treated with only one brand of high purity plasma derived factor IX concentrate.

Fifteen previously untreated patients (Pups) with severe haemophilia B (factor IX activity < or = 2 U/dl) only treated with one brand of plasma-derived high purity factor IX concentrate (FIX LFB) were studied. Age at first injection varied from 1 to 137 months and follow-up since this first injection from 21 to 86 months (median: 35). Cumulative exposure days (CED) were from 4 to over 100 (median: 26). Among these 15 Pups only one developed an inhibitor. Mutation analysis performed in all patients showed total gene deletion in the patient with inhibitor, partial gene deletion in another one, and missense mutations in 9 families. Mutation was not found in one patient. Actually, according to the data already published, only two patients were at high risk for inhibitor development in our population. Our study, although rather small, confirms the previously reported low incidence of inhibitors in haemophilia B. Large studies on incidence of FIX inhibitors are indeed difficult to perform, due to both the overall small number of severe haemophilia B patients and the low incidence of FIX inhibitors. Consequently, the impact of bias, such as prevalence of different types of gene defects in a given population, is major. Therefore, any study, dealing with incidence of FIX inhibitors in severe haemophilia B should report, for each patient, the type of gene defect.

Identification of new type 2B von Willebrand disease mutations: Arg543Gln, Arg545Pro and Arg578Leu.

We report the identification in five patients (three families) affected with type 2B von Willebrand disease (VWD) of three heterozygous nucleotide substitutions at the codon for arginine 543, 545 and 578 of the mature von Willebrand factor (VWF) subunit resulting in a glutamine, proline and leucine substitution, respectively. These mutations are located in the A1 loop where prevalent type 2B mutations (Arg543Trp, Arg545Cys and Arg578Gln) have been already identified at the same positions. By in vitro mutagenesis of full-length cDNA of VWF and transient expression in Cos-7 cells, we have shown that the six corresponding mutated recombinant VWFs (Gln543, Trp543, Cys545, Pro545, Leu578 and Gln578 rVWF) exhibited quantitatively normal expression and normal multimeric pattern but increased ristocetin- and botrocetin-induced binding to platelets as compared with that for wild-type rVWF. The two mutations at position 545 induced the greatest reactivity for GPIb of corresponding rVWFs as compared to the two mutations at positions 543 and 578.

French previously untreated patients with severe hemophilia A after exposure to recombinant factor VIII : incidence of inhibitor and evaluation of immune tolerance.

Fifty French previously untreated patients with severe hemophilia A (factor VIII < 1%), treated with only one brand of recombinant factor VIII (rFVIII), were evaluated for inhibitor development, assessment of risk factors and outcome of immune tolerance regimen. The median period on study was 32 months (range 9-74) since the first injection of rFVIII. Fourteen patients (28%) developed an inhibitor, four of whom (8%) with a high titer (> or = 10 BU). All inhibitor patients but one continued to receive rFVIII either for on-demand treatment or for immune tolerance regimen (ITR). Among these patients, inhibitor was transient in 2 (4%), became undetectable in 6 and was still present in 6. The prevalence of inhibitor was 12%. Presence of intron 22 inversion was found to be a risk factor for inhibitor development. Immune tolerance was difficult to achieve in our series despite a follow-up period of 16 to 30 months: immune tolerance was complete in only one out of the 3 patients undergoing low dose ITR and in one out of the 5 patients with high dose ITR.

Transmission of human parvovirus B19 by plasma derived factor VIII concentrates.

Although clotting factor concentrates prepared from large pools of plasma are considered to be safe for enveloped viruses (HIV, HBV and HCV), these products are likely to remain at risk for non lipid enveloped viruses. The prevalence of positive IgG serology for human parvovirus B19 (HPV-B19) was determined in 53 children suffering from haemophilia A, who had been treated from birth with only one brand of a highly purified factor VIII concentrate prepared by ion exchange chromatography with a solvent-detergent step (HPSD-VIII). HPV-B19 seropositivity ranged from 20 to 43% in 198 age matched controls. In contrast, the incidence of positive HPV-B19 IgG serology varied from 75 to 100% in haemophiliacs and all 10 severe haemophilia A patients under 3 years of age were seropositive. The presence of HPV-B19 in this clotting factor concentrate demonstrates that at least a proportion of such products continue to transmit non lipid enveloped viruses.

Hepatitis A in French hemophiliacs.

The prevalence of serum antibodies to hepatitis A virus (HAV) in 793 hemophilia A (HA) and 89 hemophilia B (HB) patients coming from 10 French Hemophilia Centers and treated since 1986-1987 with solvent/detergent (SD)-treated products is reported. The results indicated seropositivity to HAV of 29.9% in HA and 40.4% in HB patients. There was no difference among the patients according to severity of the disease, HIV serology or administration of factor VIII during the last 12 months. Seropositivity increased with age from 5.2% in HA children to 42.4% in adults (in HB the respective prevalences in the same groups were 7.7% and 56.1%). When compared to normal controls (n = 585), the prevalence of HAV seropositivity was not excessive in HA patients (n = 206). 19/20 children exclusively treated with a very-high-purity SD-factor VIII concentrate (Centre régional de transfusion sanguine, Lille) remained HAV seronegative. Six cases of HAV contamination were reported in patients with severe HA, probably reflecting the level of HAV endemy in the normal population in France. No special risk of HAV transmission linked to the SD products used in France since 1986 had thus been identified.

Comparison of anti-human and anti-porcine factor VIII inhibitor levels in 63 patients with severe haemophilia A. A French Multicentric Study.

The levels of anti-human and anti-porcine factor VIII inhibitors, measured in 63 severe haemophilia A patients, lay in the ranges of < 0.2-2,600 and < 0.2-1,300 Bethesda units per ml (BU/ml), respectively, with a median cross-reactivity of 33%. In 4 patients, human and porcine inhibitor levels were determined using both plasma, either human or porcine, and factor VIII concentrate, either very high purity human or porcine (Hyate:C). A good correlation between titres was found, whatever the source of factor VIII (plasma or concentrate). The cross-reactivity varies from 0 to over 100%, indicating that the evaluation of both human and porcine inhibitors should be mandatory before any treatment with Hyate:C. Results show that of the 46 patients with human inhibitor of more than 5 BU/ml, 21 (46%) with a low porcine inhibitor (< 5 BU/ml) could benefit from Hyate:C.

[Efficacy in viral inactivation of the concentrates of factor VIII and IX by the solvent/detergent procedure. Evaluation in patients with hemophilia]. / Efficacité de l'inactivation virale des concentrés de facteur VIII et IX par procédé solvant-détergent. Evaluation chez l'hémophile.

Human immunodeficiency virus (HIV) infection and hepatitis virus B or C (HBV, HCV) transmission are major risks following infusion of coagulation factor concentrates. Thus, several methods have been used to achieve viral inactivation of concentrates prepared from plasma collected from a large number of donors. In this study, 32 patients with haemophilia A or B (n = 31) or von Willebrand's disease (n = 1) were treated between 1987 and 1990 only with factor VIII or IX concentrates inactivated by the solvent-detergent procedure. During this period, none of these cases exhibited elevated liver enzymes (alanine amino transferase), and serological tests for HIV, HBV and HCV infections always remained negative. This suggests that the solvent-detergent procedure of concentrate inactivation is an efficient method to prevent not only HIV or HBV transmission but also HCV infection in haemophiliacs.

Clinical and biological survey of haemophilia A and B patients infused with French heat-treated concentrates.

The efficiency of heat treatment procedures of factor VIII and factor IX concentrates, prepared from voluntary, non-paid donors by three French Blood Transfusion Centres, on the inactivation of HIV and non-A, non-B hepatitis (NANB) viruses was assessed. Some 43 patients (26 haemophilia A, 17 haemophilia B) were followed for at least 1 year by testing for HIV antibodies and alanine aminotransferase (ALT). No HIV seroconversion was observed indicating that heat treatment was completely efficient. Among 26 haemophiliacs, 6 (4 haemophilia A, 2 haemophilia B) presented an elevation in ALT, indicating only a 75% reduction of NANB viral contamination.

A variant of Glanzmann's thrombasthenia with abnormal glycoprotein IIb-IIIa complexes in the platelet membrane.

Patient C.M. presented platelet function defects symptomatic of Glanzmann's thrombasthenia. However, analysis of surface-labeled platelets by SDS-polyacrylamide gel electrophoresis revealed the usual presence of the major glycoproteins, including GP IIb and GP IIIa. Platelet fibrinogen was not detected. Analysis of Triton X-100 extracts of Ca2+-washed C.M. platelets by crossed immunoelectrophoresis (CIE) showed normal amounts of GP IIb-IIIa complexes. However, when samples were electrophoresed through an agarose gel containing 125I-fibrinogen, the usual binding of fibrinogen to GP IIb-IIIa did not occur. Furthermore, the GP IIb-IIIa complexes showed an increased sensitivity to dissociation with EDTA, either after Triton X-100 solubilization or in the intact platelet membrane. For example, after incubation with EDTA at room temperature, the patient's platelets bound little of the monoclonal antibodies AP-2 or T10 (anti-GP IIb-IIIa complex) although normally binding Tab (anti-GP IIb). Patient C.M. appears to represent a subgroup of thrombasthenia where platelets contain unstable GP IIb-IIIa complexes unable to support fibrinogen binding.

[Immunological study of a population of hemophiliacs treated with non-commercial fractions]. / Etude immunologique d'une population d'hémophiles traités par des fractions non commerciales.

We studied lymphocyte subpopulations, serum beta 2 microglobulin, and viral markers in 115 hemophiliacs who are followed and treated at our center. The only clinical or biological anomaly observed is hypergammaglobulinemia. This frequent finding is independent of hemophilia type and of the intensity of substitutive treatment. This group is characterized by the fact that the patients are treated only by locally prepared coagulation fractions, essentially cryoprecipitates for hemophiliacs A, and not containing any derivative of commercial origin. This series is compared to other recent reports, some of which present a high incidence of immunologic anomalies.

[Platelet aggregation and platelet and plasma fatty acid levels in the child with migraine. Apropos of 40 case reports]. / Etude de l'agrégation plaquettaire et dosage des acides gras plaquettaires et plasmatiques chez l'enfant migraineux. A propos de 40 observations.

The authors have studied platelet aggregability in the presence of ADP and collagen in a population of 40 migrainous children between migraine attacks. They completed their investigations by a qualitative dosage in platelets and in plasma of fatty acids, precursors of prostaglandins, which are well known for their importance in platelet aggregation and vasculomotor reactions. This study was made in comparison with an equal number of controls chosen from the same age-groups. The authors didn't find the hyperaggregability observed by other authors in grown-up populations. They noticed a light-but statistically significant-diminution of linoleic acid in the platelets and in the plasma. A study based on observations does not entirely confirm for certain an alimentary origin.