The Type of Factor VIII Deficient Plasma Used Influences the Performance of the Nijmegen Modification of the Bethesda Assay for Factor VIII Inhibitors

Bert Verbruggen; Alan Giles; John Samis; Kitty Verbeek; Ewald Mensink; Irena Novákovà

doi:10.1055/s-0037-1616765

Thrombosis and Haemostasis, Table of Contents

Thromb Haemost 2001; 86(06): 1435-1439
DOI: 10.1055/s-0037-1616765

Review Article

Schattauer GmbH

The Type of Factor VIII Deficient Plasma Used Influences the Performance of the Nijmegen Modification of the Bethesda Assay for Factor VIII Inhibitors

Bert Verbruggen

¹Central Laboratory for Haematology, University Medical Centre St. Radboud, Nijmegen, The Netherlands

,

Alan Giles

³Department of Pathology, Queen‘s University, Kingston, Ontario, Canada

,

John Samis

³Department of Pathology, Queen‘s University, Kingston, Ontario, Canada

,

Kitty Verbeek

¹Central Laboratory for Haematology, University Medical Centre St. Radboud, Nijmegen, The Netherlands

,

Ewald Mensink

¹Central Laboratory for Haematology, University Medical Centre St. Radboud, Nijmegen, The Netherlands

,

Irena Novákovà

²Department of Haematology, University Medical Centre St. Radboud, Nijmegen, The Netherlands

› Author Affiliations

Abstract

Summary

We have investigated the influence of the type of factor VIII deficient plasma used on the assay results of the Nijmegen modification of the Bethesda method for factor VIII inhibitors. Immuno depleted factor VIII deficient plasmas, lacking besides factor VIII also von Willebrand factor, gave decreased inhibitor titres compared to assay results with factor VIII deficient plasmas containing von Willebrand factor suggesting the need of the latter in the test system for the stability of factor VIII:C. Moreover the performance of the assay with immuno depleted plasma was contaminated in a certain type of this plasma by the presence of a factor VIII:C inhibitor. Chemically depleted factor VIII deficient plasma appeared to give falsely elevated titres when used in combination with other types of deficient plasmas as substrate plasma in the factor VIII:C assay due to the presence of activated factor Va in the preparation. Suggestions are described with respect to the observed limitations in order to obtain reliable results.

Keywords

Factor VIII inhibitors/assay - standardisation

Full Text

References

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