Apo E levels were measured by double antibody radioimmunoassay. Plasma apo E levels in normal subjects were 9.5±1.8mg/dl. Both LCAT and LPL deficient patients had abnormal plasma lipoprotein patterns as well as 3-4 folds higher plasma apo E levels than those of normal controls.
In order to characterize abnormally high levels of apo E in these two diseases, we analyzed the distribution of apo E in plasma lipoproteins using gel chromatography (Bio-Gel A5m). In plasma of normal subject, apo E was mainly distributed in triglyceride-rich lipoproteins (Fraction A) and large HDL (Fraction B). LPL deficient patient had large Fraction A and small Fraction B, and LCAT deficient patient had large Fraction B.
From these results, we suggested that the increase of plasma apo E in LPL deficiency is due to the retention of triglyceride-rich lipoproteins and that the increase of plasma apo E in LCAT deficiency is due to the defect of apo E transfer from HDL to triglyceride-rich lipoproteins.
