Somatic Mosaicism in Hemophilia A: A Fairly Common Event

SummaryIn this study we sought to determine whether factor VUI-reactive T lymphocytes were present in hemophilia A patients with inhibitor antibodies. Peripheral blood mononuclear cells (MNC) were obtained from 12 severe hemophilia A patients having high titer inhibitors, 4 severe hemophilia A patients without inhibitors and 5 normal male subjects. B cell-depleted MNC were cultured in serum-free medium in the absence or presence of 2 µg of recombinant human factor VIII (rFVIII) per ml, and cellular proliferation was assessed after 5 days of culture by measuring 3H-thymidine incorporation. rFVIII induced marked cellular proliferation in cultures of 4 of 12 inhibitor-positive hemophilia patients: fold increase over background (stimulation index, SI) of 7.8 to 23.3. The remaining 8 inhibitor-positive patients, the 4 hemophilia patients without inhibitors and the 5 normal subjects, all had lower proliferative responses to rFVIII, SI range = 1.6 to 6.0. As a group, the inhibitor-positive subjects had significantly higher proliferative responses to rFVIII than did the inhibitor-negative and normal subjects (p < 0.05 by t-test). Cell fractionation experiments showed that T lymphocytes were the rFVIII-responsive cell type, and that monocytes were required for T cell proliferation. Thus, rFVIII-reactive T lymphocytes are present in the peripheral circulation of some inhibitor-positive hemophilia A patients. These T cells may recognize FVIII in an antigen-specific manner and play a central role in the regulation of inhibitor antibody production

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Low Prevalence of the Factor V Leiden Mutation Among “Severe” Hemophiliacs with a “Milder” Bleeding Diathesis

Thrombosis and Haemostasis ◽

10.1055/s-0038-1649922 ◽

1995 ◽

Vol 74 (05) ◽

pp. 1255-1258 ◽

Cited By ~ 50

Author(s):

Arnaldo A Arbini ◽

Pier Mannuccio Mannucci ◽

Kenneth A Bauer

Keyword(s):

Hemophilia A ◽

Factor V Leiden ◽

Protein S ◽

Factor Ix ◽

Hemophilia B ◽

Factor V ◽

Bleeding Diathesis ◽

Mutation Site ◽

Spontaneous Bleeding ◽

Factor V Leiden Mutation

SummaryPatients with hemophilia A and B and factor levels less than 1 percent of normal bleed frequently with an average number of spontaneous bleeding episodes of 20–30 or more. However there are patients with equally low levels of factor VIII or factor IX who bleed once or twice per year or not at all. To examine whether the presence of a hereditary defect predisposing to hypercoagulability might play a role in amelio rating the hemorrhagic tendency in these so-called “mild severe” hemophiliacs, we determined the prevalence of prothrombotic defects in 17 patients with hemophilia A and four patients with hemophilia B selected from 295 and 76 individuals with these disorders, respectively, followed at a large Italian hemophilia center. We tested for the presence of the Factor V Leiden mutation by PCR-amplifying a fragment of the factor V gene which contains the mutation site and then digesting the product with the restriction enzyme Mnll. None of the patients with hemophilia A and only one patient with hemophilia B was heterozygous for Factor V Leiden. None of the 21 patients had hereditary deficiencies of antithrombin III, protein C, or protein S. Our results indicate that the milder bleeding diathesis that is occasionally seen among Italian hemophiliacs with factor levels that are less than 1 percent cannot be explained by the concomitant expression of a known prothrombotic defect.

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A Hexagonal (II) Phase Phospholipid Neutralization Assay for Lupus Anticoagulant Identification

Thrombosis and Haemostasis ◽

10.1055/s-0038-1649671 ◽

1993 ◽

Vol 70 (05) ◽

pp. 787-793 ◽

Cited By ~ 77

Author(s):

Douglas A Triplett ◽

Linda K Barna ◽

Gail A Unger

Keyword(s):

Hemophilia A ◽

Clinical Laboratory ◽

Neutralization Assay ◽

Confirmatory Test ◽

Specific Factor ◽

Clinical Settings ◽

Drug Induced ◽

Variable Screening ◽

Routine Clinical Laboratory

SummaryLupus anticoagulants (LAs) are immunoglobulins (IgG, IgM, or both) which interfere with in vitro phospholipid (PL) dependent tests of coagulation (e.g. APTT, dilute PT, dilute Russell Viper Venom Time). These antibodies may be identified in a wide variety of clinical settings. With the exception of heparinized patient samples, the presence of LAs is often the most common cause of an unexplained APTT in a routine clinical laboratory. The diagnosis of LAs is difficult due to variable screening reagent sensitivity and intrinsic heterogeneity of LAs. Recently, Rauch and colleagues have shown human monoclonal hybridoma LAs were inhibited by hexagonal (II) phase PLs. In contrast, lamellar phase PLs had no effect. We have evaluated a new assay system, Staclot LA®, which utilizes a hexagonal (II) phase PL (egg phosphatidylethanolamine [EPE]) as a confirmatory test for LAs. Plasma samples from the following patient populations were studied: LA positive, heparinized, oral anticoagulated, hemophilia A and B, and specific factor inhibitors (factors V, VIII, IX). Unlike previous studies, the LA positive patients were a mixed population including: autoimmune diseases, drug-induced, and post-infection. Our findings confirm the specificity of hexagonal (II) phase PL neutralization of LAs.

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Treatment of Hemophilia A with a Highly Purified Factor VIII Concentrate Prepared by Anti-FVIIIc Immunoaffinity Chromatography

Thrombosis and Haemostasis ◽

10.1055/s-0038-1648373 ◽

1992 ◽

Vol 67 (01) ◽

pp. 019-027 ◽

Cited By ~ 47

Author(s):

Joseph E Addiego ◽

Edward Gomperts ◽

Liu Shu-Len ◽

Patricia Bailey ◽

Suzanne G Courter ◽

...

Keyword(s):

Factor Viii ◽

Hemophilia A ◽

Virus Transmission ◽

Human Albumin ◽

Immunoaffinity Chromatography ◽

Exchange Chromatography ◽

Pharmacokinetic Studies ◽

Enveloped Viruses ◽

Clinically Significant ◽

Detergent Mixture

SummaryTo reduce the risk of pathogenic virus transmission associated with the therapeutic administration of plasma-derived antihemophilic factor (FVIIIc), a process utilizing anti-FVIIIc immunoaffinity chromatography to isolate FVIIIc has been developed. In addition, the starting cryoprecipitate solution has been treated with an organic solvent/detergent mixture to inactivate lipid-enveloped viruses. A final ion exchange chromatography step is used to further remove contaminants, e.g., anti-FVIIIc antibody, potentially leached with FVIIIc during the immunoaffinity step. The purified FVTII is stabilized for lyophili-zation and storage by the addition of human albumin. The monoclonal anti-FVIIIc antibody used in the immunoaffinity step of the process is not detectable in the final preparation. Viral reduction studies performed at specific steps of the process demonstrate that 11 logs of human immunodeficiency virus (HIV) and greater than 4-5 logs of other lipid-enveloped viruses are inactivated within the first 30 s of exposure to the solvent/ detergent mixture and 4-5 logs of various model viruses, e. g. Endomyocarditis virus (EMC), are physically removed during washing of the immunoaffinity column. The lyophilized product is reconstituted using sterile water in a matter of seconds.The pharmacokinetics of Hemofil® M were compared to those obtained using a standard heat-treated concentrate (Hemofil® CT) in five severe factor VIII deficient hemophiliacs in a randomized, cross-over study. No statistically significant differences were observed in mean half life (p >0.6) or median recovery (p = 0.4) between the two preparations. No clinically significant adverse effects were observed in patients receiving either FVIII preparation.In addition, 43 patients at 18 different centers underwent pharmacokinetic studies, with a nominal dose of 50 u/kg FVIIIc Hemofil® M. The mean recovery was 103.6%, and the t 1/2 was 14.6 h. The recovery of FVIII in this group was as expected, providing an increase of assayed FVIII of approximately 2% per unit of FVTII/kg infused.Clinical trials using Hemofil® M have been initiated in 124 hemophilia A patients. The safety and efficacy of Hemofil® M has been established. To date, 0 of 60 patients tested have seroconverted to HIV. None of the previously untreated patients show clinical or laboratory evidence of Non-A, Non-B hepatitis (NANB), with 21 patients remaining negative as far as presence of antibodies to the Hepatitis C virus (a-HCV negative) at least 6 months after the initial infusion. There is no evidence of neoantigenicity, evidenced by seroconversion to murine antibody. An 8.7% (2 of 23) prevalence of anti-FVIIIc inhibitor development has been observed in previously untreated patients with FVIIIc⩽3%, receiving only the monoclonally purified solvent/ detergent treated FVIII concentrate while on study and on poststudy surveillance. All patients demonstrated clinical hemostasis following product use for either on demand bleeding or surgical prophylaxis.

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A Survey of the Effectiveness of Prothrombin Complex Concentrates in Controlling Hemorrhage in Patients with Hemophilia and Anti-Factor VIII Antibodies

Thrombosis and Haemostasis ◽

10.1055/s-0038-1650077 ◽

1980 ◽

Vol 44 (01) ◽

pp. 039-042 ◽

Cited By ~ 14

Author(s):

Philip M Blatt ◽

Doris Ménaché ◽

Harold R Roberts

Keyword(s):

Factor Viii ◽

Ad Hoc ◽

Hemophilia A ◽

Working Party ◽

International Committee ◽

Factor Ix ◽

Prothrombin Complex Concentrates ◽

Factor Viii Concentrates

SummaryThe treatment of patients with hemophilia A and anti-Factor VIII antibodies is difficult. Between July 1977 and June 1978, a survey was carried out by an ad hoc working party of the subcommittee on Factor IX concentrates of the International Committee on Thrombosis and Hemostasis to assess the effectiveness of Prothrombin Complex Concentrates in controlling hemorrhage in these patients. The results are presented in this paper and, although subjective, support the view that these concentrates are not as effective in patients with inhibitors as Factor VIII concentrates are in patients without inhibitors.

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Prevalence of Inhibitors in a Population of 3435 Hemophilia Patients in France

Thrombosis and Haemostasis ◽

10.1055/s-0038-1648507 ◽

1992 ◽

Vol 67 (06) ◽

pp. 600-602 ◽

Cited By ~ 85

Author(s):

Y Sultan ◽

Keyword(s):

Hemophilia A ◽

Hemophilia B ◽

Study Group ◽

Cooperative Study ◽

Population Prevalence ◽

French Study ◽

Number Of Patients ◽

High Incidence ◽

Recombinant Fviii ◽

High Responders

SummaryA cooperative study between the 37 centers of the French Hemophilia Study Group was undertaken to establish the prevalence of inhibitor patients in the French hemophilia population. The prevalence reported in the literature varies widely from 3.6% to 17.5%. Some of the studies are dealing with a small number of patients and inhibitor patients are reported either to the total number of hemophiliacs or to the severely affected ones. The French study provided information concerning 3,435 hemophiliacs and showed a prevalence of 6.2% for the overall population. Prevalence of inhibitors was found to be 7% in the population of hemophilia A patients and 12.8% in the population of severely affected ones. The prevalence of inhibitors in the population of hemophilia B patients was 2% and 4% in the population of severely affected hemophilia B patients. The cooperative study also showed that 47.5% of inhibitors are detected before 10 years of age and that 82% of inhibitor patients are high responders. Analysis of inhibitor detection in patients under the age often showed that there was a peak in the population of 2 years old children. Although not comparable to the present study the high incidence of inhibitors with ultrapurified and recombinant FVIII reported in previously untransfused patient may be borne in mind.

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Investigations on the Nature of Hemophilia A

Thrombosis and Haemostasis ◽

10.1055/s-0038-1654959 ◽

1963 ◽

Vol 09 (01) ◽

pp. 030-052 ◽

Cited By ~ 4

Author(s):

Eberhard Mammen

Keyword(s):

Factor Viii ◽

Human Plasma ◽

Barium Sulfate ◽

Freeze Drying ◽

Room Temperature ◽

Hemophilia A ◽

Normal Human Plasma ◽

Normal Human ◽

And Storage ◽

Prothrombin Activation

SummaryIn this paper an inhibitor is described that is found in hemophilic plasma and serum different from any till now described inhibitor. The inhibitor only inhibits prothrombin activation in the “intrinsic clotting systems”. This inhibitor is probably not present in normal human plasma or serum. It is destroyed by ether and freeze drying, is labile to acid and storage at room temperature. It is stable upon dialysis and has not been adsorbed on barium sulfate, aluminum hydroxide or kaolin. It precipitates at 50% v/v saturation with alcohol. The nature of this inhibitor seems to be a protein or lipoprotein.Factor VIII was isolated from hemophilic plasma. The amount isolated was the same as from normal plasma and the activity properties were not different. Hemophiliacs have normal amounts of factor VIII.

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Homozygous Hemophilia A in a Female

Thrombosis and Haemostasis ◽

10.1055/s-0038-1660111 ◽

1985 ◽

Vol 54 (03) ◽

pp. 728-728 ◽

Cited By ~ 3

Author(s):

P Sié ◽

C Caranobe ◽

M Benalioua ◽

B Boneu

Keyword(s):

Hemophilia A

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