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Measurement of Factor V Activity in Human Plasma Using a Microplate Coagulation Assay
Published on: September 9, 2012
Assay discrepancies with highly purified factor VIII concentrates
N J Dawson1, G Kemball-Cook, T W Barrowcliffe
1Division of Haematology, National Institute for Biological Standards and Control, South Mimms, Herts., UK.
Haemostasis
|January 1, 1989
Summary
Assay methods significantly impact the measured potency of factor VIII concentrates, especially highly purified ones. Careful evaluation of factor VIII:C activity assay methodologies is crucial for accurate assessment.
Area of Science:
- Hematology
- Biochemistry
- Clinical Chemistry
Background:
- Accurate measurement of factor VIII concentrate potency is vital for effective hemophilia treatment.
- Different assay methodologies may yield varying results, particularly for highly purified factor VIII products.
Purpose of the Study:
- To compare the potencies of monoclonal-antibody-purified and conventional factor VIII concentrates using various assay methods.
- To investigate the influence of assay methodology and von Willebrand factor on factor VIII:C activity determination.
Main Methods:
- Assayed two monoclonal-antibody-purified (A and B) and one conventional (C) factor VIII concentrate.
- Utilized one-stage, two-stage, and chromogenic assay methods against the 3rd International Standard.
- Employed immunodepleted plasmas and haemophilic plasma for comparative analysis.
Main Results:
- One-stage assays with immunodepleted plasmas yielded lower potencies for all concentrates compared to haemophilic plasma.
- Discrepancies were most pronounced for highly purified products (A and B).
- Absence of von Willebrand factor contributed to observed low potencies.
- Product A showed 50% higher potencies by one-stage assay (haemophilic plasma) versus two-stage or chromogenic methods.
Conclusions:
- Assay methodology significantly influences the assessed potency of factor VIII concentrates.
- Highly purified factor VIII concentrates require careful evaluation of assay techniques for accurate factor VIII:C activity determination.
- The role of von Willebrand factor in assay results warrants further investigation.
