Enzyme-linked immunoabsorbant assay of apolipoprotein AII in plasma, with use of a monoclonal antibody.

We produced a monoclonal antibody (C2-22) to human apolipoprotein (Apo) AII and describe its use in an enzyme-linked immunoabsorbant assay (ELISA) for Apo AII in human plasma and lipoprotein subfractions. No cross reactivity of the antibody with Apo CI, CII, CIII, E, or ablumin was detected. Apo AI and low- and very-low-density lipoprotein cross reacted by 0.25%, less than 0.2%, and less than 0.3%, respectively. Whole plasma high-density lipoprotein (HDL) and HDL subfractions (HDL2 and HDL3) produced parallel displacement curves. This quantitative ELISA is based on competition between solid-phase-bound Apo AII and free Apo AII. Bound C2-22 is detected by alkaline-phosphatase-labeled second antibody. The standard curve for the assay is linear for plasma diluted 500-fold originally containing 140 to 1140 mg of Apo AII per liter. Delipidation of plasma samples exposed no additional antigenic sites. Within- and between-run CVs were respectively 8.4% and 8.7% at 327 mg/L of Apo AII, and 6.8% and 7.4% at 587 mg/L. Results correlated well with those by a polyvalent-antisera-based RIA procedure: r = 0.916, p less than 0.01, RIA = 0.896 ELISA -19.1 mg/L.