Detection and IgG subclass analysis of antibodies to factor VIII in multitransfused haemophiliacs and healthy individuals.

Using a binding assay to immobilized factor VIII (F VIII) (ELISA) we measured the amount of IgG with binding capacity to FVIII, in the plasma of patients with an inhibitor to F VIII, in multitransfused haemophiliacs without inhibitor and in a control group of blood donors. It was shown that the amount of IgG bound to VIII was elevated in patients with an inhibitor although a weak correlation could be established between the inhibitor titre (BU) and the amount of bound IgG. In all haemophiliacs without inhibitor, IgG bound to F VIII were present. Although the mean value of IgG bound to F VIII was significantly lower than the amount detected in patients with F VIII inhibitors, a group of patients developed an equal amount of IgG recognizing the F VIII molecules to the amount of IgG measured in inhibitor patients. These results indicate that the presence of an inhibitor is not related to the amount of specific IgG bound to F VIII but more likely to the position of epitopes recognized by specific IgG. The presence of IgG bound to F VIII was detected in 92% of control blood donors and an inhibitor to F VIII ranging from 0.5 to 1.3 BU mL(-1) in 17% of them. The isotypes of bound immunoglobins were identified in patients and controls: IgG4 subclass was predominant only in patients with an inhibitor and usually associated with antibodies of one or more of the other subclasses. In noninhibitor patients, very few had antibodies of IgG4 subclass with binding capacity to F VIII. These results raised the question of the clinical significance of these antibodies in multitransfused patients. The study indicates that binding assay is a complementary test to be used in multitransfused patients but cannot be used instead of the coagulation tests for detection of inhibitors.

Biological effects of a S/D-treated, very high purity, von Willebrand factor concentrate in five patients with severe von Willebrand disease.

A highly purified von Willebrand factor (vWf) concentrate with low factor VIII (FVIII) content was tested to evaluate its biological effects in five patients with severe von Willebrand disease (vWd). The patients were infused with a single dose of this product corresponding to approximately 65 IU vWf:RCo and approximately 11 IU FVIII:C/kg and were followed up for 48 h. The plasma levels of FVIII and vWf and the multimeric pattern of vWf were determined before and 1, 3, 6, 12, 24 and 48 h after infusion. In all patients the recovery (93 +/- 14%) and half-life (13 +/- 1 h) of vWf were consistent and normal and sustained FVIII levels were attained. In four patients both the duration and the volume of shed blood were measured after one incision with a standardized template method of bleeding time (BT). The duration of bleeding was completely corrected in two out of the four patients and partially corrected in the other two while the volume of shed blood was completely corrected in three patients and partially corrected in the fourth. However, the time for correction of both BT parameters was variable between patients. These data indicate that the vWf concentrate can correct the quantitative defects related to plasma vWf deficiency in vWd patients whereas the effect on template BT is less reproducible.

Behçet syndrome associated with protein S deficiency.

Behçet syndrome is a multisystem disorder characterized by ocular, mucocutaneous, articular, gastrointestinal and neurologic abnormalities. We report here an unusual case of Behçet syndrome, characterized by the importance of the thrombotic events (7 phlebitis of both legs and resection of two toes). Additional manifestations of the Behçet syndrome occurred only 10 years after the first thrombotic episode. The oldest daughter of the propositus and his brother suffered also from thrombophlebitis; this familial history of thrombosis led to the performance of a haemostatic study. A congenital protein S deficiency was found in the propositus and in three of his children. Normal protein S levels were found in nine unrelated patients with Behçet syndrome. Thus this observation suggests that, when thrombotic manifestations are the first and major symptom of Behçet syndrome, an additional cause of thrombosis has to be investigated.

Investigation of factor VIII:C gene restriction fragment length polymorphisms and search for deletions in hemophiliac subjects in Algeria.

The frequency of alleles for intragenic (intron 17 and intron 25) and extragenic (DXS15 and DXS52) F8C RFLPs was investigated in the Algerian population. Altogether 287 X chromosomes (97 males and 95 females) were studied. The allele frequencies found with the two intragenic F8C RFLPs were not substantially different from those reported in a Mediterranean population. At the highly polymorphic extragenic DXS52 locus the distribution in Algeria differed from that found in France. A new allele (14 kb), called 1 DZ, was found in 3.1% of the chromosomes. Fifty-one families with hemophilia A were studied with the same probes (374 subjects). Of the females, 94% were informative for at least one intra- or extragenic RFLP. Two recombinations were found between DXS52 and F8C, of which one occurred between the DXS15, DXS52 block and F8C, indicating that the two anonymous loci are on the same side of the F8C gene. Only two obvious gene deletions were observed in 73 unrelated hemophiliacs: one encompassed exons 14-22 (about 4.3 kb of cDNA and 36 kb of genomic DNA); the other removed the last exon (exon 26, representing 2 kb of cDNA).

A new case of 'type II' inherited protein S deficiency.

Protein S inherited deficiency is associated with high risk of recurrent venous thrombotic disease (Broekmans et al, 1985a, b). Protein S exists as two forms in plasma, either free and functionally active or complexed with C4b-binding protein (C4b BP) and inactive (Dahlbäck & Stenflo, 1981). We report here the case of a 26-year-old woman and her brother, 28 years old, both suffering from recurrent venous thrombosis since the age of 20, diagnosed as severe protein S deficiency according to the following data: free protein S: 2.5-3% by ELISA, undetectable by electroimmunodiffusion (EID); total protein S: 13-16% by ELISA, 21-18% by EID, C4b BP: normal levels. Crossed immunoelectrophoresis using anti-protein S antibodies revealed only traces of protein S associated with C4b BP and no free protein S. All these assays were performed in the absence of any anticoagulant therapy. Among the investigated relatives, less severe protein S deficiency was observed in three children of the propositus: total protein S levels ranging from 41% to 50% (EID), 40-53% (ELISA); free protein S levels ranging from 16% to 18% (EID), 10-12% (ELISA); normal C4b BP levels. Crossed immunoelectrophoresis revealed traces of free protein S but a significant amount of protein S associated with C4b BP. From these results, we consider, according to Comp's classification (Comp et al, 1986a), that the propositus and her brother are the second case of protein S deficiency type II to be reported in the literature while her children belong to the type I category.

[Platelet aggregation in diabetes mellitus in children]. / Etude de l'agrégation plaquettaire au cours du diabète sucré de l'enfant.

Platelets-endothelial cells interaction appears to cause vascular damage in diabetes. Platelet aggregation was studied in 24 diabetic children and adolescents (mean age: 12.2 years, mean duration of diabetes: 3.3 years), with only one presenting microangiopathy complications (retinopathy). Platelet aggregation was found to be normal, suggesting that there is usually no platelet hyperactivity in diabetic children.

Antithrombin III Alger: a new homozygous AT III variant.

A qualitative abnormality of antithrombin III (AT III) was found in the plasma of a 41-year old patient. The plasmatic AT III antigen concentration was 130% and the progressive anti-F IIa and anti-F Xa activities were normal (105% and 137%). The plasma heparin cofactor activity was less than 10%, when measured by F IIa or F Xa inhibition. Crossed immunoelectrophoresis of AT III in the presence of heparin revealed in the plasma an abnormal slow-moving peak. When tested by affinity chromatography on heparin Sepharose, this abnormal AT III did not bind to heparin. Among the investigated relatives, 5 subjects had normal AT III levels, whatever the test used, the nine others having reduced levels of antithrombin heparin cofactor activity (45-61%) but normal levels of immunoreactive AT III (97-122%). Consanguinity was found in the family history. We therefore considered our patient as homozygous for an AT III molecular abnormality affecting the binding site for heparin.