Immunoassay with High Sensitivity by Using Immunoliposomes and Membrane Lysis Reaction of the Complement System

免疫分析技术依赖于抗原和抗体之间的高亲和力和高灵敏度，被广泛应用于微量分析和临床检测。然而，目前的固相免疫分析需要分离结合抗体和游离抗体，因此既耗时又麻烦。本文提出了一种新的免疫脂质体均相免疫分析方法，即脂质体与抗体(抗原)偶联。在这种方法中，这些脂质体是通过补体系统在形成抗原-抗体复合体时的裂解反应而被破坏的，而脂质体包裹的标志物的释放量作为该反应发生的定量指标。主要研究结果如下：1.免疫脂质体在含有明胶的缓冲溶液中稳定数月，包埋标记物不丢失。与兔免疫球蛋白偶联的免疫脂质体主要通过补体的替代途径被破坏。由于经典的补体途径被激活，加入抗兔免疫球蛋白抗体显著促进了标志物的释放。利用免疫脂质体可以在同一系统中测量这两条通路的活性。通过添加针对该抗原的特异性抗体来破坏与该抗原偶联的免疫脂质体。标志物的释放与免疫脂质体表面形成的抗原抗体复合体的数量成正比。

Immunoassays, which depend on the high affinity and sensitivity between antigen and antibody, are widely used in microanalyses and clinical assays. The present solid-phase immunoassays, however, need separation between bound and free antibodies and so are time-consuming and troublesome. In the present work a new homogeneous immunoassay by using immunoliposomes, i. e. liposomes coupled with antibodies (antigens), was developed. In this method, these liposomes are destroyed by the lysis reaction of the complement system on the formation of antigen-antibody complexes, and the released amount of liposome-encapsulated marker serves as a quantitative indication of the reaction taking place. The results are summarized as follows :1. The immunoliposomes were stable in buffer solutions containing gelatin for several months without any loss of encapsulated marker.2. The immunoliposomes coupled with rabbit IgG were destroyed mainly by the alternative pathway of complement. Addition of anti-rabbit IgG antibody enhanced significantly marker release because of the activation of the classical pathway of complement. The activities of both the pathways can be measured in the same system by using the immunoliposomes.3. The immunoliposomes coupled with an antigen were destroyed by addition of the specific antibody against the antigen. The marker release was proportional to the amount of antigen-antibody complexes formed on the surface of the immunoliposomes.