Direct measurement of HDL cholesterol: Method eliminating apolipoprotein E-rich particles

It has been reported that the existing direct method of high density lipoprotein (HDL) cholesterol measures particles enriched with apolipoprotein E (apoE). The aim of our study was to investigate a new analytical protocol to directly measure HDL cholesterol that eliminates apoE-rich particles. The interactions of four lipoproteins (HDL3, HDL2, LDL, and VLDL + chylomicron) with surfactants, divalent cations, sugars, and lectins were investigated. By analyzing sera, HDL3, and HDL2, we examined the relationships among the measurements obtained by our protocol, a precipitation method using heparin-MnCl2, and a commercially available kit for this direct method. A significant difference was found between the direct method and the heparin-MnCl2 method, but not between our protocol and the heparin-MnCl2 method. Multiple regression analysis showed that the difference between the direct method and the heparin MnCl2 method is dependent on sources of apoE-rich HDL. In conclusion, our protocol enables a direct measurement of HDL cholesterol that eliminates apoE-rich particles. (C) 2001 Wiley-Liss, Inc.