Thromb Haemost 1985; 54(03): 709-712
DOI: 10.1055/s-0038-1660103
Original Article
Schattauer GmbH Stuttgart

The Dilute Phospholipid APTT: A Sensitive Assay for Verification of Lupus Anticoagulants

Barbara M Alving
The Departments of Hematology and Membrane Biochemistry, Walter Reed Army Institute of Research and the Hematology-Oncology Service, Walter Reed Army Medical Center, Washington, D. C., USA
,
Phillip E Baldwin
The Departments of Hematology and Membrane Biochemistry, Walter Reed Army Institute of Research and the Hematology-Oncology Service, Walter Reed Army Medical Center, Washington, D. C., USA
,
Roberta L Richards
The Departments of Hematology and Membrane Biochemistry, Walter Reed Army Institute of Research and the Hematology-Oncology Service, Walter Reed Army Medical Center, Washington, D. C., USA
,
Beverly J Jackson
The Departments of Hematology and Membrane Biochemistry, Walter Reed Army Institute of Research and the Hematology-Oncology Service, Walter Reed Army Medical Center, Washington, D. C., USA
› Author Affiliations
Further Information

Publication History

Received 19 March 1985

Accepted 29 August 1985

Publication Date:
19 July 2018 (online)

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Summary

A simple sensitive method for verification of lupus anticoagulants utilizing dilution of phospholipid in the activated partial thromboplastin time (APTT) system is described. Patient plasma, mixed with an equal volume of normal plasma, is activated with micronized silica. To this mixture are added different dilutions of Thrombofax® and then calcium chloride. Clotting times are plotted linearly against the logarithm of the phospholipid dilutions and slopes are calculated by regression analysis. In this assay the mean negative slope of 19 plasmas that contained antiphospholipid activity was five times greater than those of normal plasma or those obtained from patients having single or multiple coagulation factor deficiencies such as those induced by warfarin. The assay can be modified to test heparinized plasmas. Thus, it is a sensitive means by which to verify the presence of lupus anticoagulants in patients who have congenital or acquired factor deficiencies or who are receiving anticoagulant therapy.