The Liposome Company, Inc.

Joyce Rauch

Andrew S Janoff

Colin P Tilcock

Theodore F Taraschi

For use in a lipid-dependent diagnostic assay, a stable aqueous suspension of a phospholipid which normally has a hexagonal (H,) organization when dispersed in an aqueous medium without detergent, the suspension containing the phospholipid, a detergent, and an aqueous phase. In the stable suspension, the phospholipid remains in suspension at a temperature of 25&deg; C. for at least one hour. The suspension is suitable for providing the phospholipid to an assay for lupus anticoagulants which includes the step of pre-incubating a test sample with the phospholipid.

Lipid-dependent diagnostic assays

Lipid-dependent diagnostic assays are provided wherein the test sample to be assayed is pre-incubated with one or more phospholipids having a hexagonal (H.sub.II) organization, with lipidic particles, or with bilayer-forming lysophospholipids such as monooleoylphosphatidylethanolamine (MOPE). The pre-incubation results in reduced false positives due to antiphospholipid antibodies, such as, lupus anticoagulants, which may be present in the test sample, without changing the overall character, including the normal baseline, of the assay. Surprisingly, in accordance with the invention, it has been found that only hexagonal phospholipids, lipidic particles, and bilayer-forming lysophospholipids can be used, and, in particular, lamellar (bilayer) phospholipids (other than such lysophospholipids) cannot be used. An assay for diagnosing systemic lupus erythematosus (SLE) is also provided.

Improved lipid-dependent diagnostic assays are provided wherein the test sample to be assayed is pre-incubated with one or more phospholipids having a hexagonal (H.sub.II) organization or with lipidic particles. The pre-incubation results in reduced false positives due to anti-phospholipid antibodies, such as, lupus anticoagulants, which may be present in the test sample, without changing the overall character, including the normal baseline, of the assay. Suprisingly, in accordance with the invention, it has been found that only hexagonal phospholipids and lipidic particles can be used, and, in particular, lamellar (bilayer) phospholipids cannot be used. An assay for diagnosing systemic lupus erythematosus (SLE) is also provided.

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Montreal, Canada

Joyce Rauch