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

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
› Author Affiliations
Further Information

Publication History

Received 29 June 1998

Accepted after revision 01 September 1998

Publication Date:
07 December 2017 (online)

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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.