Immunonephelometric determination of apolipoprotein A-1 in hyperlipoproteinemic serum.

Abstract

The intensity of scattered light varies with the size of the scattering particles. Studying the quantitative immunonephelometric determination of apolipoprotein A-1 (apo A-1), we observed that the different particle sizes of lipoproteins must be taken into account in immunonephelometry if apo A-1 is a constituent of the lipoprotein particles. Because interaction between large lipoproteins and immunocomplexes of high-density lipoproteins increases light scattering nonspecifically, false estimations may be obtained in serum with excessive hyperlipoproteinemia. Furthermore, the accessibility of antigenic sites of apo A-1 in intact high-density lipoproteins is limited. Immunonephelometry of apo A-1 in serum necessitates therefore the elimination of various interferents, which we have achieved by a single one-step extraction of lipids in a two-phase liquid system. With n-hexanol/polyfluoro-polychloro-polyethylene, about 90% of the serum lipids are extracted and only apolipoprotein B is precipitated at the interphase. This pretreatment eliminates the interferences caused by excessive hypertriglyceridemia and therefore greatly facilitates the endpoint immunonephelometry of apo A-1 in normal and pathological serum samples.

Speciated Human High-Density Lipoprotein Protein Proximity Profiles

“…These include their sites of generation , , different interaction capabilities with various plasma factors − , and catabolism . In the context of their heterogeneity, several methods have been used to determine HDL:apolipoprotein stoichiometry, including immunonephelometry , and cross-linking followed by gel-based interpretations . The former method measures scattered light intensity as a function of particle size, and the stoichiometries are then estimated compared to standards with known compositions , .…”

“…In the context of their heterogeneity, several methods have been used to determine HDL:apolipoprotein stoichiometry, including immunonephelometry , and cross-linking followed by gel-based interpretations . The former method measures scattered light intensity as a function of particle size, and the stoichiometries are then estimated compared to standards with known compositions , . The latter method determines the migration distance of cross-linked HDL particles by sodium dodecyl sulfate−polyacrylamide gel electrophoresis (SDS−PAGE), and the molecular mass ( M r ) determinations of these complexes are conducted with respect to a set of M r standards.…”