[Development of the HDL-C and LDL-C direct methods and the subsequent evolution].

Today, more than a decade after the development of direct methods for determining HDL-cholesterol (HDL-C) and LDL-cholesterol (LDL-C) concentrations, there are calls to review the reagents in response to discrepancies in patient samples with increased levels of atypical lipoproteins, such as apoE-rich HDL, IDL, Lp-X, and Lp-Y. Seven direct HDL-C assays showed different reactions toward apoE-rich HDL in sera from patients with CETP deficiency and cholestasis. On the other hand, the reactivity of the direct LDL-C assays to serum samples with elevated levels of IDL, Lp-X, and Lp-Y varied considerably between assay kits from each manufacturer. We have also examined the anti-atherogenic functions of apoE-rich HDL from the serum of healthy individuals and patients with CETP deficiency and cholestasis. The ability of apoE-rich HDL to remove cholesterol from cholesterol-loaded macrophages showed that the apoE-rich HDL from CETP-deficient serum took up more cholesterol than apoE-poor HDL (p < 0.01), but no significant differences were observed for apoE-rich HDL from patients with cholestasis.