Characterization of a Monoclonal Antibody that Binds to Apolipoprotein E and to Lipoprotein of Human Plasma Containing APO E. Applications to ELISA Quantification of Plasma APO E

Abstract

This study describes the development of an enzyme-linked immunosorbent assay for human apolipoprotein E (apo E). A mouse monoclonal IgG₁ antibody named E01 against apolipoprotein E was selected from five antibodies secreted by hybridomas. This antibody had a high affinity for apo E ((K a 1.2 × 10⁷ L.M⁻¹ for purified apo E and K = 1.05 × 10⁷ L.M⁻¹ for native apo E in very low density lipoproteins) in liquid phase and recognized every isoform of apo E but not other proteins in VLDL. Competition experiments with ¹²⁵I apo E showed that its binding affinity for the E in every density class (VLDL, HDL, LDL) and in serum was the same. This antibody was used for the quantification of human apo E in serum by enzyme linked immunoassay. E01 was coated on microtiter plates and a polyclonal peroxidase-conjugate was used as second antibody. A good correlation was observed between the values obtained for apo E using both monoclonal and polyclonal antibodies.