Use of Antigen-Coupled Liposomes for Homogeneous Immunoassays of Polyclonal Antibody

This chapter describes the measurement of the concentration of antibodies and the measurement of the complement activities by use of immune liposomes. In the former case, the effects of the concentration, association constant and its heterogeneity of polyclonal antibodies, as well as the preparation conditions of immune liposomes on the sensitivity and reliability of the assay were quantitatively studied. For preparation of liposomes used for antigen coupling, N-[4-(p-maleimidophenyl) butyryl] dipalmi-toylphosphatidylethanolamine (MPB-DPPE) was synthesized by the procedures previously reported. The amount of antigen coupled to liposomes depended on the molar ratio of MPB-DPPE constituting the liposomes as well as on the molar ratio of modified antigen to MPB-DPPE in the reaction mixture. By use of antigen-coupled liposomes, specific antibodies are detected, and the total and alternative pathway of complement activities of complement can also determined within 2 h.