Characterization of antigen-coupled liposomes for homogenous immunoassay of polyclonal antibodies

Abstract

Abstract The effects of the preparation conditions of antigen-coupled liposomes on their characteristics in liposome immune lysis assay (LILA) of specific antibodies were studied. The amount of antigen coupled to liposomes depended on the molar ratio of N-[4-( p -maleimidophenyl)butyryl] dipalmitoyl phosphatidylethanolamine (MPB-DPPE) constituting the liposomes as well as on the molar ratio of modified antigen to MPB-DPPE in the reaction mixture. In depended also on the molecular weight of the antigen. With increases in the amount of antigen coupled to liposomes higher sensitivity and a wider dynamic range were obtained. Though an increase in the average association constant between antigen and antibody lowered the detection limit, the wide dynamic range, which prevents false positive results in LILA, can be controlled mainly by the amount of coupled antigen.