[Apolipoprotein E and activity of cholesterol esters transport in type IIA and IIB hyperlipoproteinemia]

The authors studied the activity of cholesterol esters transport (CET), concentrations of apolipoprotein E in the blood and high density lipoproteins (HDLP) in parallel with other parameters of lipoprotein metabolism in 79 males and 62 females. 122 of them had ischemic heart disease (IHD) and primary hyperlipoproteinemia (HLP). 19 healthy controls were normolipidemic. Activation of CET and relative lowering of apoE content in HDLP with relevant increase in lipoproteins containing apoB were seen only in type IIB HLP. CET activity in controls was related to a significant positive correlation with concentrations of both cholesterol (CS) and CS esters (CSE) in HDLP and HDLP3 and negative correlation with the proportion free CS/CSE in HDLP. Opposite to normolipidemic subjects, in type IIB HLP there was a negative relationship between CET activity and HDLP3 CS level and positive--between free CS/CSE in HDLP but not with concentration of CSE and total CS in HDLP. In type IIA HLP patients no relationships were registered between CET activity and HDLP content of total CS and CSE as well as with HDLP3 CS level. In type IIB HLP a significant correlation was found between level of HDLP CS and CET activity. Concentration of apoE in HDLP correlated with apoB level in the serum but not with quantity of HDLP CS. Patients with type IIA HLP exhibited a significant negative correlation between CET activity and HDLP apoE. These patients had no dependence of CET activity on HDLP CS but had positive correlation between HDLP apoE and HDLP CS in the serum. Thus, defects of reverse CS transport may be induced not only by changes in CET activity but also by apoE distribution among lipoproteins of different classes.