Automated immunoturbidimetric assay of serum apolipoprotein A-II using the Cobas-Bio centrifugal analyser: influence of hyperlipoproteinemia.

A quantitative automated immunoturbidimetric procedure for the analysis of apolipoprotein A-II (Apo A-II) in human serum is described. Dilution of antibody with a 5% solution of PEG 6000 enhanced the quantification. The within- and between-assay coefficients of variation were less than 5%. Results correlated well with those obtained by classic electroimmunodiffusion and immunonephelometry. No extraction of samples with organic solvent was necessary, whatever the triglyceride concentration. Large lipoproteins such as VLDL and immunocomplexes did not affect the method, nor was there interference from icteric or hemolyzed serum or from serum with excessive hyperlipemia. Physiological values of Apo A-II were determined in a normal population. Concentrations were found to be age-dependent, and higher in women than in men. The procedure is very suitable for the rapid, precise, reproducible and inexpensive assay of Apo A-II.