Low density lipoprotein subfractions and relationship to other risk factors for coronary artery disease in healthy individuals.

By a recently developed sensitive density gradient ultracentrifugation method, the distribution of low density lipoprotein (LDL) subfractions was studied in the serum of healthy blood donors (20 to 62 years old). For each subject, we observed a specific LDL subfraction distribution characterized by the relative contribution of the three major LDL subfractions, LDL-1 (1.020 to 1.028 g/ml), LDL-2 (1.027 to 1.034 g/ml), and LDL-3 (1.033 to 1.039 g/ml), to total LDL. Statistical analysis was performed by using the LDL density variable defined as: (% of LDL-1) x 1.024 + (% of LDL-2) x 1.0305 + (% of LDL-3) x 1.036 as a continuous variable. Controlling for age, smoking habits, relative body weight and, when appropriate, for gender, it appeared that: 1) dense LDL subfraction patterns characterized by a predominant LDL-3 subfraction and a decreased LDL particle size were more likely to be found among men than among women, 2) with increasing density of LDL, the levels of serum triglycerides increased, whereas the concentration of HDL cholesterol and the ratio of LDL cholesterol to LDL apolipoprotein (apo) B decreased, and 3) the best model with significant contribution in the prediction of the LDL subfraction distribution was the three-variable model: total cholesterol, serum triglycerides, and LDL apo B (R2 = 0.40), whereas the best two-variable model consisted of serum triglycerides and high density lipoprotein cholesterol (R2 = 0.37). These data are consistent with results from a study described previously in which a different approach based on LDL subfraction quantification by gradient gel electrophoresis of whole plasma was used.