[Cholesterol, phospholipid and apoB composition of LDL: comparison of precipitation and ultracentrifugation methods]

Cholesterol, phospholipid and apoB levels were determined in LDL precipitated by amphiphatic polymers (Biomérieux kit, Marcy-l'Etoile, France). Intra-assay and inter-assay analysis performed on 4 serum pools were satisfactory. For 113 sera (triglyceride level less than 4.5 mmol/l, absence of VLDL-remnants), the 3 variables were well correlated with those of centrifuged LDL (0.93 less than r less than 0.98); however, LDL-cholesterol values were significantly higher (p less than 0.001), and those of LDL-phospholipids (p less than 0.001) and LDL-apoB (p less than 0.005) significantly lower. The correlations between the 3 constituents studied gave statistically different regression coefficients for the two methods. It is concluded that these precipitated lipoproteins do not seem to correspond to LDL but to "LDL markers".