Thromb Haemost 1998; 80(06): 930-935
DOI: 10.1055/s-0037-1615391
Letters to the Editor
Schattauer GmbH

A Plasma Coagulation Assay for an Activated Protein C-independent Anticoagulant Activity of Protein S

Authors

  • Merel van Wijnen*

    1   Department of Haematology, University Hospital Utrecht
    2   Institute of Biomembranes, Utrecht University, The Netherlands
  • Cornelis van ’t Veer

    1   Department of Haematology, University Hospital Utrecht
    4   Present address: Dr. C. van ’t Veer, Department of Surgery, Maastricht University, The Netherlands
  • Joost C.M. Meijers

    1   Department of Haematology, University Hospital Utrecht
    2   Institute of Biomembranes, Utrecht University, The Netherlands
  • Rogier M. Bertina

    3   Thrombosis and Haemostasis Research Center, Department of Haematology, Leiden University Medical Center, The Netherlands
  • Bonno N. Bouma

    1   Department of Haematology, University Hospital Utrecht
    2   Institute of Biomembranes, Utrecht University, The Netherlands
Further Information

Publication History

Received 29 June 1998

Accepted after revision 01 September 1998

Publication Date:
07 December 2017 (online)

Preview

Summary

To study the physiological importance of the activated protein C (APC)-independent anticoagulant activity of protein S, we developed an assay specific for this activity. The ability of protein S to prolong the clotting time in an APC-independent way was expressed as the ratio of the clotting time in a plasma sample divided by the clotting time in the presence of a polyclonal antibody against human protein S (both after 1:1 dilution in protein S-C4BP deficient plasma). The mean protein S-dependent anticoagulant ratio (PSdAR) was 1.53 ± 0.18 in 34 healthy controls, and was significantly lower in 16 heterozygous protein S deficient patients (PSdAR = 1.15 ± 0.09). In plasmas from patients under oral anticoagulant therapy the mean PSdAR was within the range of the control population (1.50 ± 0.18). The mean total protein S antigen level in these plasmas was 58%, suggesting a higher specific APC-independent anticoagulant activity of protein S in these patients than in normals.

This functional protein S assay can be used for the laboratory diagnosis of protein S deficiency, and to study the mechanism of the APC-independent anticoagulant activity in plasma.

* M. van Wijnen is supported by a grant from the Netherlands Heart Foundation (93.108). J.C.M. Meijers is an Established Investigator of the Netherlands Heart Foundation.