Abstract: Dehydrated liposomes are prepared by drying liposome preparations under reduced pressure in the presence of one or more protective sugars, e.g., the disaccharides trehalose and sucrose. Preferably, the protective sugars are present at both the inside and outside surfaces of the liposome membranes. Freezing of the liposome preparation prior to dehydration is optional. Alternatively, the protective sugar can be omitted if: (1) the liposomes are of the type which have multiple lipid layers; (2) the dehydration is done without prior freezing; and (3) the dehydration is performed to an end point which results in sufficient water being left in the preparation (e.g., at least 12 moles water/mole lipid) so that the integrity of a substantial portion of the multiple lipid layers is retained upon rehydration.

Abstract: Methods and compositions are described for the preparation of alpha-tocopherol vesicles, the bilayers of which comprise a salt form of an organic acid derivative of alpha-tocopherol such as the Tris salt form of alpha-tocopherol hemisuccinate. The method is rapid and efficient and does not require the use of organic solvents. The alpha-tocopherol vesicles may be used to entrap compounds which are insoluble in aqueous solutions. Such preparations are especially useful for entrapping bioactive agents of limited solubility, thus enabling administration in vivo.

Abstract: Methods and compositions are described for the preparation of lipid vesicles, the bilayers of which comprise a salt form of an organic acid derivative of a sterol such as the tris-salt form of a sterol hemisuccinate. The method is rapid, efficient, and does not require the use of organic solvents. The sterol hemisuccinate vesicles may be used to entrap compounds which are insoluble in aqueous solutions. Such preparations are especially useful for entrapping bioactive agents of limited solubility thus enabling administration in vivo.

Abstract: 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.

Abstract: An immunoassay utilizing a novel liposome composition in which there is incorporated a stabilizing or destabilizing component and an antigen. The presence of cognate antibodies in test samples is detected by the alteration of the supramolecular structure of the liposomes resulting in changes in stabilization. Destabilization can be detected, and in certain cases, caused by, the addition of magnesium or calcium ions. Increased stabilization can be detected by the polymerization of bilayer components in response to ultraviolet light. Antibody-antigen interactions at the liposome surface mediate the stabilization/destabilization response.

Abstract: 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.

Abstract: An assay for detecting SLE antibodies utilizing a novel liposome composition in which there is entrapped a divalent cation responsive indicator. The presence of such antibodies is detected by their stabilization of the supermolecular structure of the liposomes. Such stabilization can be detected, and in certain cases, caused by, the addition of magnesium or calcium ions.

Abstract: A new and substantially improved type of lipid vesicle, called stable plurilamellar vesicles (SPLVs), are described, as well as the process for making the same. SPLVs are stable during storage and can be used in vivo for the sustained release of compounds and in the treatment of disease.