Plasma cholesteryl ester transfer protein is lowered by treatment of hypercholesterolemia with cholestyramine

Cholestyramine (INN, colestyramine) treatment of subjects with hypercholesterolemia reduced the plasma level of cholesteryl ester transfer protein (CETP) as measured by radioimmunoassay (CETP-RIA) and, as expected, also reduced the levels of total cholesterol, low-density lipoprotein (LDL) cholesterol, and apolipoprotein B. The extent of CETP variation was significant only in the subjects whose LDL cholesterol levels were reduced by more than 25%. Furthermore, CETP-RIA was correlated with total cholesterol, LDL cholesterol, and apolipoprotein B concentrations. Plasma CETP was also measured by an indirect procedure that uses high-density lipoprotein (HDL) 14C-cholesteryl ester and very low-density lipoprotein cholesterol from a pool of plasma donors, and the patient's plasma as the source of CETP. The two procedures for CETP determination correlated well with each other, although the CETP-RIA was more sensitive in the detection of changes of plasma CETP ascribed to cholestyramine (INN, colestyramine) treatment. The rise of plasma HDL cholesterol levels after cholestyramine probably resulted from the reduction of CETP activity.