Thromb Haemost 1981; 45(01): 051-054
DOI: 10.1055/s-0038-1650127
Original Article
Schattauer GmbH Stuttgart

Respective Roles of Antithrombin III and Alpha 2 Macroglobulin in Thrombin Inactivation

A M Fischer
The Department of Haematology, University Hospital Necker-Enfants Malades, Paris, France
,
J Tapon-Bretaudiere
The Department of Haematology, University Hospital Necker-Enfants Malades, Paris, France
,
A Bros
The Department of Haematology, University Hospital Necker-Enfants Malades, Paris, France
,
F Josso
The Department of Haematology, University Hospital Necker-Enfants Malades, Paris, France
› Author Affiliations
Further Information

Publication History

Received 05 September 1980

Accepted 01 December 1980

Publication Date:
04 July 2018 (online)

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Summary

In order to investigate the mechanism of thrombin inactivation in the presence of both antithrombin III (AT III) and α 2-macroglobulin (α 2 M), thrombin and the inhibitors have been purified from human material and thrombin inactivation studied using purified reagents either alone or added to defibrinated plasma. Comparison of clotting and amidolytic activities of residual thrombin allowed to measure the amount of thrombin bound to α 2 M. In a purified reagent system as well as in plasma, part of exogenous thrombin is bound to α 2 M. The amount of bound thrombin is related to α 2 M concentration. Conversely, previous plasma α 2 M depletion by immunoabsorption increases the consumption of heparin-cofactor activity by exogenous thrombin. Thus AT III and α 2 M compete for thrombin inactivation. This finding could be of practical interest in clinical situations associating high plasma α 2 M levels and a decrease of AT III concentration.