Immunonephelometry of Apolipoprotein A-Il in Plasma

A quantitative assay based on endpoint immunonephelo-metry was developed for human apolipoprotein A-Il (apoA-Il) in plasma or serum. Dilution of plasma samples with a 0.1 mol/L solution of sodium cholate enhanced the quantification. We used either purified apoA-II as the primary standard or plasma as a secondary standard. Results correlated well (r = 0.90) with those by a double-antibody radioimmunoassay for 63 serum samples from both normal and hyperlipemic indi-viduals. The interassay coefficient of variation for the immun-onephelometric assay was 7 % within a working range be-tween 0.05 and 0.7.rg of apoA-ll per sample (corresponding to a 1500-fold final dilution of serum). No extraction of samples with organic solvent is necessary if the triglyceride concentration is <4 g/L. Additional Keyphrases: hyperilpidemia. coronary heart dis