The use of streptavidin-biotin interaction for preparation of reagents for complement-dependent liposome immunoassay of proteins: detection of latrotoxin.

We have developed liposome sensitization by a protein, latrotoxin (LT), using immobilization of biotinylated LT via streptavidin with biotinylated phosphatidylethanolamine contained in liposomes. The use of such liposomes in the complement-dependent homogeneous liposome immune lysis assay (LILA) has allowed us to detect in the test sample as little as 2 micrograms/ml of polyclonal and 50-100 ng/ml of monoclonal IgG and IgM antibodies to LT. LT concentration in solution was determined by inhibition of immune lysis by free LT.