Antibody Phenotyping Test for the Human Apolipoprotein E2 Isoform

[摘要] Numerous methods have been described to determine the apolipoprotein E (apoE) phenotype or genotype of individuals (1)(2). These techniques are relatively time-consuming, and interpretation of the results can be difficult. Here, we report the development of a rapid and specific antibody-based test for the identification of the apoE2 isoform. Previously, we characterized the binding properties of a panel of anti-human apoE monoclonal antibodies (mAbs) (3)(4)(5). The locations of epitopes of selected mAbs from the panel are presented in Fig. 1A⇓ . Although neither mAb 6C5 nor 3H1 showed apoE isoform specificity, mAb 2E8 recognized an epitope that includes the apoE LDL receptor-binding site and resembles the LDL receptor in terms of its fine specificity.Several apoE variants that are defective in their ability to mediate binding of lipoproteins to the LDL receptor and are associated with type III hyperlipoproteinemia are poorly recognized by mAb 2E8. These include the relatively common apoE2 (Arg158-Cys) isoform as well as many, but not all, of the rare variants, including apoE2 (Arg136-Ser). Thus, similar to DNA-based phenotyping assays, our immunoassay is designed to detect the most common apoE2 isoforms. When mixtures of purified apoE2 and apoE3 were prepared and tested in a sandwich ELISA format using mAb 6C5 for capture and the 2E8-horseradish peroxidase (HRP) conjugate for the identification, there was selective identification of the apoE3 isoform (Fig. 1D⇓ ). Similarly, there was selective identification of apoE2 in mixtures …

[学科分类] 过敏症与临床免疫学