Large-liposome agglutination reagent and method

An agglutination assay reagent for determination of serum or plasma reagin antibody comprising

• liposomes containing cardiolipin at a molar concentration between about 1 and 20% and prepared by (a) forming a dispersion of lipid vesicles having heterogeneous sizes both less than and greater than 1 micron, and (b) treating the dispersion to remove vesicles whose sizes are less than about 1 micron, wherein incubation of the liposomes in the presence of reagin antibody at room temperature for 5 minutes is effective to produce liposome liposome agglutination on a slide, and
• a dye trapped by the liposomes at a concentration effective to allow said liposomes to be visualized directly without magnification on a slide.

A rapid agglutination assay method for determination of a multivalent ligand-binding analyte, said method comprising

• providing a suspension of liposomes (a) prepared by forming a dispersion of lipid vesicles having heterogeneous sizes both less than and greater than 1 micron, and treating the dispersion to remove vesicles whose sizes are less than about 1 micron, and (b) having a surface array of ligand molecules and a trapped dye, and
• mixing the suspension with the analyte on a slide to produce liposome agglutination which is readily detectable, without magnification, within about five minutes at room temperature.

A rapid-agglutination assay method for determination of reagin antibody comprising

• providing a suspension of reagent particles composed of liposomes containing cardiolipin at a molar concentration between about 1%-20% and a trapped dye and prepared by (a) forming a dispersion of lipid vesicles both having heterogeneous sizes less than and greater than 1 micron, and (b) treating the dispersion to remove vesicles whose size is less than about 1 micron, and
• mixing the reagent with a sample of the antibody to produce agglutination which is readily detectable, without magnification, after 2 to 5 minutes at room temperature.

In an assay procedure which includes reacting multivalent ligand-binding molecules with a suspension of ligand-coated liposomes having heterogeneous sizes both greater and less than about 1 micron, to produce liposome agglutination in proportion to the concentration of ligand-binding molecules, the improvement comprising:

• enhancing the rate and extent of liposome agglutination by treating the liposome suspension to remove liposomes whose sizes are less than about 1 micron.

An agglutination assay reagent comprising liposomes predominantly in the 1-20 micron size range, wherein the interior liposome spaces are substantially filled with a semi-rigid gel or a polymerized matrix,

• each liposome having a surface array of ligand molecules at a surface concentration effective to produce liposome agglutination within about 5 minutes, when the reagent is incubated at room temperature with a multivalent ligand-binding analyte on a slide, and
• a dye trapped by the liposomes at a concentration adapted to allow such agglutination to be visualized readily without magnification on a slide.

A rapid agglutination assay method for determination of a multivalent ligand-binding analyte, said method comprising

• providing a suspension of reagent particles composed of liposomes primarily in the 1-20 micron size range, each liposome having a surface array of ligand molecules and a trapped dye, wherein the interior liposome spaces are substantially filled with a semi-rigid gel or polymerized matrix, and
• mixing the suspension with the analyte on a slide to produce particle agglutination which is readily detectable, without magnification, within about 5 minutes at room temperature.