A Low-Molecular-Weight Phenotype of Apolipoprotein(a) as a Factor Provoking Accumulation of Cholesterol by THP-1 Monocyte-Like Cells.

Increased concentration of lipoprotein(a) is a risk factor of coronary heart disease. lipoprotein(a) consists of LDL-like and highly polymorphic apolipoprotein(a). Here we studied the effect of lipoprotein(a)-containing sera with different apolipoprotein(a) phenotypes on lipid accumulation by THP-1 monocyte-like cells. Cholesterol concentration in lysates of THP-1 cells was significantly higher after their incubation with lipoprotein(a)-containing serum samples with low-molecular-weight phenotype of apolipoprotein(a) in comparison with samples with a high-molecular-weight apolipoprotein(a) phenotype irrespective of initial cholesterol level as well as serum concentrations of apoB-100, oxidized LDL, and circulating immune complexes. The presence of the most atherogenic small dense LDL subfractions in examined sera in addition to a low-molecular-weight apolipoprotein(a) phenotype resulted in significant elevation of cholesterol accumulation by THP-1 cells. The data obtained explain greater atherogenicity of lipoprotein(a) with low-molecular-weight apolipoprotein(a) phenotype.