Apolipoprotein A-I containing lipoproteins in coronary artery disease.

At least 2 main types of lipoprotein particles are identified within HDL. Those which contain apo A-I and apo A-II (LpA-I:A-II) and those which contain apo A-I but not apo A-II (LpA-I). This study was designed to elucidate to what degree the HDL cholesterol decrease observed in coronary artery disease affects these 2 types of lipoprotein particles. Concentrations of LpA-I:A-II and LpA-I were measured in plasma from 100 normolipidemic male subjects with angiographically defined coronary artery disease (CAD(+)) or without CAD (CAD(-)) and from 50 control subjects, matched for age. CAD(+) subjects had significantly lower levels of HDL cholesterol, total apo A-I, and LpA-I than controls. When compared to CAD(-) subjects, only their levels of HDL cholesterol and LpA-I were found lower. In both cases (CAD(+) vs CAD(-) and CAD(+) vs controls), LpA-I levels were decreased while LpA-I:A-II levels were unchanged. Even, when the levels of their total plasma lipids and lipoproteins are normal, atherosclerotic patients are characterized by a different distribution of apo A-I between LpA-I and LpA-I:A-II. These data support the view that LpA-I might represent the "antiatherogenic" fraction of HDL.