Dissociation-enhanced lanthanide fluorescence immunoassay of lipoprotein(a) in serum.

Lipoprotein(a), a human serum lipoprotein structurally related to low-density lipoprotein (LDL), contains in addition to apolipoprotein B (apo B) apolipoprotein(a) [apo(a)], a glycoprotein with a strong homology to plasminogen. Lp(a) is a risk factor for coronary heart disease and ischemic cerebrovascular disease. Several immunological techniques are used to quantify Lp(a) in human serum, including radioimmunoassays, rocket immunoelectrophoresis, and enzyme-linked immunosorbent assays. Only the last method is suitable for large-scale clinical studies. We describe another solid-phase immunoassay, based on the dissociation-enhanced lanthanide fluorescence system Delfia (Wallac Oy), and outline the technical details. A polyclonal antiserum directed against Lp(a) was used as the capture antibody. Two kinds of detection antibodies were applied, a polyclonal antiserum against apo B and the polyclonal antiserum against Lp(a). The results agree excellently with the values estimated by rocket immunoelectrophoresis. This assay is easily established, measures Lp(a) in a wide concentration range, and is suitable for screening large populations.