Abstract
We have investigated a double precipitation procedure for the determination of serum HDL2-and HDL3-cholesterol by Gidez et al (1982), and its clinical availability was evaluated. The procedure is composed of a initial precipitation of apo B containing lipoprotein with heparin-MnCl2 and a further precipitation of HDL2 by adding dextran sulfate (MW 15, 000, Sochibo, Boulogne, France) to the initial supernatant.
1. The concentrations of serum total HDL-cholesterol by the precipitation method with heparin-MnCl2 (final concentration of MnCl2: 0.091M) were compared with those of the preparative ultracentrifuge. The correlation coefficient of the values between two methods was r=0.940, and the difference of the means was 1.1mg/dl.
2. With regard to the second precipitation, we have found that a optimal final concentration of dextran sulfate required to precipitate HDL2 was 0.30g/dl or above, which differed from the concentration of 0.13g/dl originally recommended by Gidez. By the precipitation with dextran sulfate concentration of 0.30g/dl, the values of HDL2-and HDL3-cholesterol gave a best correlation compared with those of the ultracentrifuge method, and their correlation coefficients were r=0.933, 0.927 respectively. But the precipitation method showed slightly higher results for HDL2-cholesterol and slightly lower values for HDL3-cholesterol.
3. By using this method, we have confirmed that mean HDL2-cholesterol values of the patients with coronary heart disease (18.1±7.3) and hypertriglycemia (16.1±6.0) were significantly lower than that of control (29.2±13.3mg/dl), and mean HDL3-cholesterol value of the patients with cirrhosis of the liver (7.8±3.0) was characteristically lower than that of control (23.3±4.9mg/dl).
We have concluded that this precipitation procedure for determination of HDL subclasses was very useful in clinical studies, because not only the results by this method correlated well with those obtained by the preparative ultracentrifuge, but also the procedure was simple and rapid.
