Concentration of apolipoprotein-E in high-density lipoproteins of human blood plasma

The aim of this study was to determine apolipoprotein (apo) E concentration in the high-density lipoprotein (HDL) fractions of normolipidemic subjects. ApoE concentrations in total blood plasma and HDL fractions were measured by an immunoturbidimetric method. We observed that the quantitative distribution of apoE among different lipoprotein classes depends on the total plasma apoE concentration: at low total plasma apoE concentration, a substantial amount of apoE was associated with HDL; an increase in total plasma apoE was accompanied by a more equal distribution of apoE among lipoprotein fractions. The concentration of apoE in the HDL fraction was stable and did not depend on the total plasma apoE concentration. Thus, the preservation of a constant concentration of apoE in HDL due to its redistribution among lipoprotein classes is a priority when total plasma apoE concentrations change. This feature should be considered at diagnosis and for the treatment of lipid disorders.