Testing Factor VIII Activity by Using the Chromogenic Assay in Carriers of Hemophilia A

2006 ◽  
pp. 179-182
Author(s):  
W. Miesbach ◽  
Th. Vigh ◽  
I. Scharrer
Keyword(s):  
Factor Viii ◽  
Hemophilia A ◽  
Factor Viii Activity ◽  
Chromogenic Assay

scholarly journals Anti-factor VIII antibodies of hemophiliac patients are frequently directed towards nonfunctional determinants and do not exhibit isotypic restriction

Blood ◽  
1993 ◽  
Vol 82 (8) ◽  
pp. 2452-2461 ◽  
Author(s):  
JG Gilles ◽  
J Arnout ◽  
J Vermylen ◽  
JM Saint-Remy
Keyword(s):  
Antibody Response ◽  
Factor Viii ◽  
Specific Antibody ◽  
Hemophilia A ◽  
Significant Proportion ◽  
Functional Method ◽  
Specific Antibody Response ◽  
Functional Assays ◽  
Epitope Specificity ◽  
Chromogenic Assay

Abstract A significant proportion of hemophilia A patients receiving transfusions of factor VIII (FVIII) develop a specific antibody response towards FVIII. These antibodies are usually detected by assays in which they inhibit the function of the molecule, such as the Bethesda clotting test. We have prepared anti-FVIII antibodies by specific immunoadsorption from the plasma of four hemophiliacs with stable inhibitor levels. The isotypic distribution of such antibodies was determined and their capacity to bind to insolubilized FVIII was compared with their inhibitory activity in two functional assays, namely, the Bethesda assay and a chromogenic assay. In addition, the FVIII epitope specificity was determined by competition with monoclonal antibodies for the binding to insolubilized FVIII. We show here that (1) anti-FVIII antibodies are not isotypically restricted; thus, a significant proportion of specific IgG2 was found; (2) antibodies are frequently directed towards epitopes of FVIII that are not directly involved in the function of the molecule and therefore escape detection in the Bethesda method or chromogenic assay; and (3) each patient shows a unique pattern of FVIII epitope recognition. We conclude that evaluation of anti-FVIII antibodies by a functional method does not provide an accurate evaluation of the specific antibody response. These findings have important implications for the comparison of the immunogenicity of FVIII molecules produced by different technologies and for the development of methods to control anti-FVIII antibody production.

scholarly journals Postpartum Acquired Hemophilia: A Rare Cause of Postpartum Hemorrhage

2013 ◽  
Vol 2013 ◽  
pp. 1-2 ◽  
Author(s):  
Srikanth Seethala ◽  
Sumit Gaur ◽  
Elizabeth Enderton ◽  
Javier Corral
Keyword(s):  
Factor Viii ◽  
Hemophilia A ◽  
Factor Vii ◽  
Normal Vaginal Delivery ◽  
Factor Viii Inhibitor ◽  
Activity Levels ◽  
Factor Viii Activity ◽  
Acquired Hemophilia A ◽  
Acquired Hemophilia ◽  
Viii Inhibitor

A 36-year-old female started having postpartum vaginal bleeding after normal vaginal delivery. She underwent hysterectomy for persistent bleeding and was referred to our institution. An elevation of PTT and normal PT made us suspect postpartum acquired hemophilia (PAH), and it was confirmed by low factor VIII activity levels and an elevated factor VIII inhibitor. Hemostasis was achieved with recombinant factor VII concentrates and desmopressin, and factor eradication was achieved with cytoxan, methylprednisolone, and plasmapheresis.

scholarly journals Assessing the Performance of Extended Half-Life Coagulation Factor VIII, FC Fusion Protein by Using Chromogenic and One-Stage Assays in Saudi Hemophilia A Patients

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Tarek M. Owaidah ◽  
Hazzaa A. Alzahrani ◽  
Nouf S. Al-Numair ◽  
Abdulmjeed O. Alnosair ◽  
Amelita M. Aguilos ◽  
...  
Keyword(s):  
Factor Viii ◽  
Half Life ◽  
Hemophilia A ◽  
Coagulation Factor ◽  
Time Interval ◽  
One Stage ◽  
Chromogenic Assay ◽  
Significant Difference ◽  
Mean Differences ◽  
The One

Background. The one-stage assay is the most common method to measure factor VIII activity (FVIII : C) in hemophilia A patients. The chromogenic assay is another two-stage test involving purified coagulation factors followed by factor Xa-specific chromogenic substrate. Aim. This study aimed to assess the discrepancy and correlation between the chromogenic and one-stage assays in measuring FVIII : C levels in hemophilia patients receiving Extended Half-Life Elocta® as a recombinant extended half-life coagulation factor. Methods. We performed a study comparing the measurements of FVIII : C levels by the chromogenic versus the one-stage assays at different drug levels. Data of FVIII : C levels, dosage, and the time interval from administration to measurement were retrieved from the hospital records. The correlation, mean differences, and discrepancy between the two assays were calculated. The linear regression analysis was used to predict the time interval till reaching 1% FVIII : C. Results. Fourteen patients with 56 samples were included in the study. Of them, 13 patients were receiving Elocta® as a prophylactic, while one was receiving Elocta® on demand. One-third of these samples showed a discrepancy between the chromogenic and one-stage assays. The two assays were well correlated. Mean differences were significant at the individual and the time interval level. The time since the last Elocta® injection could significantly predict FVIII : C levels (β = 0.366, P<0.001). Conclusion. Our findings suggested a significant difference between both methods; the FVIII : C levels measured by the one-stage assay were less than those estimated by the chromogenic assay. However, the measurements of FVIII levels by the two assays were well correlated but discrepant in one-third of the samples. The levels of FVIII : C reach 1% after 5.4 days since the last Elocta® administration.

Correction of the coagulation defect in hemophilia A mice through factor VIII expression in skin

Blood ◽  
2000 ◽  
Vol 95 (9) ◽  
pp. 2799-2805 ◽  
Author(s):  
Steven S. Fakharzadeh ◽  
Yue Zhang ◽  
Rita Sarkar ◽  
Haig H. Kazazian
Keyword(s):  
Transgenic Mice ◽  
Factor Viii ◽  
Hemophilia A ◽  
Systemic Disease ◽  
Factor Viii Activity ◽  
Human Factor Viii ◽  
Plasma Factor ◽  
Transgenic Lines ◽  
Rag 1 ◽  
Involucrin Promoter

To test the hypothesis that factor VIII expressed in the epidermis can correct hemophilia A, we generated transgenic mice in a factor VIII–deficient background that express human factor VIII under control of the involucrin promoter. Mice from 5 transgenic lines had both phenotypic correction and plasma factor VIII activity. In addition to the skin, however, some factor VIII expression was detected in other tissues that have stratified squamous epithelia. To determine whether an exclusively cutaneous source of factor VIII could correct factor VIII deficiency, we grafted skin explants from transgenic mice onto mice that are double knockouts for the factor VIII and RAG-1 genes. Two graft recipients had plasma factor VIII activity of 4% to 20% of normal and improved whole blood clotting compared with factor VIII–deficient mice. Thus, expression of factor VIII from the epidermis can correct hemophilia A mice, thereby supporting the feasibility of cutaneous gene therapy for systemic disease.

Quantitative Evaluation of Factor VIII in Factor VIII Products.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4012-4012
Author(s):  
Saulius Butenas ◽  
Behnaz Parhami-Seren ◽  
Matthew T. Gissel ◽  
Edward D. Gomperts ◽  
Kenneth G. Mann
Keyword(s):  
Factor Viii ◽  
Protein Content ◽  
Quantitative Evaluation ◽  
Hemophilia A ◽  
Specific Activity ◽  
Full Length ◽  
Recombinant Factor Viii ◽  
Factor Viii Activity

Abstract Several factor VIII products, recombinant and natural, have been used for hemophilia A treatment worldwide. Typically, two activity-based assays (factor Xase and aPTT) are used for the assessment of factor VIII concentration in these products. Frequently, the results are dependent upon the assay and its modifications in different laboratories. In this study, we evaluated five pharmacologic factor VIII products (three lots of each) in three activity-based assays and in two immunoassays for the concentration and activity of factor VIII protein. Two factor VIII products were plasma-derived (Immunate and Hemofil M) and three were recombinant; two of these contained full-length factor VIII (Recombinate and Kogenate) and one was B-domainless (ReFacto). Albumin-free full-length recombinant factor VIII was used as a standard in all assays. In the factor Xase assay, all recombinant factor VIII products and Immunate at 1U/ml (indicated by manufacturer) showed activity similar to that of 0.7nM (1U/ml) standard, whereas activity of Hemofil M was 64–68% of the standard. In the aPTT assay both full-length recombinant products and Hemofil M displayed activity similar to the standard, whereas Immunate had increased (142% of standard) and ReFacto decreased (83% of standard) activity. In synthetic plasma, all three recombinant products had standard-like activity, whereas Hemofil M and Immunate were slightly more active than standard. The ELISA immunoassay revealed that the factor VIII protein content in Recombinate, Kogenate and Hemofil M corresponded to the units assigned by manufacturers (1.4–1.6x1012U/mol vs1.4x1012U/mol calculated for standard), whereas the specific activity of Immunate was 50% of that expected (0.7x1012U/mol). In contrast, the specific activity of ReFacto was almost 3-fold that of full-length factor VIII (4.0x1012U/mol). The data of this study indicate that: 1) factor VIII activity estimated in different assays gives dissimilar results; 2) the specific activity of factor VIII in various factor VIII products is different and, as a consequence, administration of an equal factor VIII activity in U/ml means the administration of different amounts of factor VIII protein.

scholarly journals Features of factor VIII activity measurement in Arg531His mutant detected in patients with mild hemophilia A

2008 ◽  
Vol 19 (6) ◽  
pp. 788-795 ◽  
Author(s):  
Hiroshi INABA ◽  
Yutaka YATOMI ◽  
Keiko SHINOZAWA ◽  
Takashi SUZUKI ◽  
Kagehiro AMANO ◽  
...  
Keyword(s):  
Factor Viii ◽  
Hemophilia A ◽  
Activity Measurement ◽  
Factor Viii Activity

Partial Reconstitution of Factor VIII Activity from a Mild Crm+ Hemophilia A Patient by Replacement of the Defective A2 Domain

1998 ◽  
Vol 79 (05) ◽  
pp. 943-948 ◽  
Author(s):  
W. C. Pieneman ◽  
P. Fay ◽  
E. Briët ◽  
P. H. Reitsma ◽  
R. M. Bertina
Keyword(s):  
Factor Viii ◽  
Hemophilia A ◽  
Wild Type ◽  
Coding Region ◽  
Factor Viii Activity ◽  
Factor Ixa ◽  
Factor Viiia ◽  
Factor Viii Antigen ◽  
A2 Domain ◽  
Reduced Activity

SummaryWe further characterised the abnormal factor VIII molecule (factor VIII Leiden) of a Crm+, mild hemophilia A patient with a factor VIII activity of 0.18 IU/ml and a factor VIII antigen of 0.95 IU/ml. Mutation analysis of the coding region, promoter and 3’ untranslated region of the factor VIII gene revealed the presence of a C to T substitution at codon 527. This nucleotide change predicts the replacement of an arginine to tryptophan in the A2 domain close to a suggested binding site for factor IXa. Since a previous study of this mutant factor VIII protein suggested that this protein had a reduced affinity for factor IXa, position 527 in the protein might be involved in the interaction with factor IXa.In this study we gathered evidence for our hypothesis that the Arg to Trp mutation at position 527 is the cause of the reduced activity of factor VIII Leiden. Replacement of the mutated A2 domain by wild type A2 domain partially corrected the defect.Factor VIII from normal and factor VIII Leiden plasma was concentrated by cryoprecipitation, activated with thrombin and incubated with excess wild type A2 domain. Competition with excess isolated human A2 domain resulted in a partial reconstitution of the factor VIIIa activity of thrombin treated factor VIII Leiden. This supports the hypothesis that the mutation in the A2 domain is the cause of the reduced factor VIII activity.

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