Thromb Haemost 1986; 56(03): 349-352
DOI: 10.1055/s-0038-1661681
Original Article
Schattauer GmbH Stuttgart

Characterization of an Abnormal Antithrombin (Milano 2) with Defective Thrombin Binding

Authors

  • A Tripodi

    The A. Bianchi Bonomi Hemophilia and Thrombosis Center and Institute of Internal Medicine, University of Milano, Italy
  • A Krachmalnicoff

    The A. Bianchi Bonomi Hemophilia and Thrombosis Center and Institute of Internal Medicine, University of Milano, Italy
  • P M Mannucci

    The A. Bianchi Bonomi Hemophilia and Thrombosis Center and Institute of Internal Medicine, University of Milano, Italy
Further Information

Publication History

Received 20 June 1986

Accepted after revision 12 September 1986

Publication Date:
18 July 2018 (online)

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Summary

Four members of an Italian family (two with histories of venous thromboembolism) had a qualitative defect of antithrombin III reflected by normal antigen concentrations and halfnormal antithrombin activity with or without heparin. Anti-factor Xa activities were consistently borderline low (about 70% of normal). For the propositus’ plasma and serum the patterns of antithrombin III in crossed-immunoelectrophoresis with or without heparin were indistinguishable from those of normal plasma or serum. A normal affinity of antithrombin III for heparin was documented by heparin-sepharose chromatography. Affinity adsorption of the propositus’ plasma to human α-thrombin immobilized on sepharose beads revealed defective binding of the anti thrombin III to thrombin-sepharose. Hence the molecular defect of this variant appears to be at the active site responsible for binding and neutralizing thrombin, thus accounting for the low thrombin inhibitory activity.