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 μg/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. The sensitivity of the LT assay varied from 1 × 10-9 to 5-50 × 10-9 m when antiserum (polyclonal antibodies) and monoclonal antibodies to LT were correspondingly used. The results show that a streptavidin-biotin spacer can be used to immobilize protein antigens on liposomes for a subsequent application in LILA. The suggested technique greatly simplifies the sensitization procedure and extends the applicability of the LILA. © 1992.