Radioimmunoassay studies of human apolipoprotein E.

Abstract

A B S T R A C T This report describes the development and first applications of a sensitive and specific double antibody radioimmunoassay for human apolipoprotein E (apoE). ApoE was purified from the very low density lipoproteins of hypertriglyceridemic patients by heparin-agarose affinity chromatography, DEAE-cellulose chromatography, and preparative polyacrylamide gel electrophoresis. The purified apoprotein had an amino acid composition characteristic of apoE and resulted in the production of monospecific antisera when injected into rabbits. The radioimmunoassay, which was carried out in the presence of 5 mM sodium decyl sulfate, had a working range of 0.8-12 ng. The withinassay coefficient ofvariation was 9% and the coefficient of variation for systematic between-assay variability was 3%. Prior delipidation of samples with organic solvents did not alter their immunoreactivity.In 26 normal volunteers, the mean plasma apoE concentration was 36+13 .tg/ml.

Determination by the SRID Method of Normal Values of Serum Apolipoproteins (A-I, A-II, B, C-II, C-III, and E) in Normolipidemic Healthy Japanese Subjects

“…Nevertheless, there are only a few reports in which the apolipoprotein levels were investigated in a large number of healthy subjects [11][12][13][14][15][16]. Because a reagent kit for measuring apolipoproteins had recently become commercially available, we planned to determine the normal levels of apolipoproteins A-I, A-II, B, C-II, C-III, and E in Japanese.…”

Concentration and composition of lipoproteins in blood plasma of the WHHL rabbit. An animal model of human familial hypercholesterolemia.

“…29 This may account for the increased concentration of apo E in plasma, but an increased rate of hepatic secretion of apo E cannot be excluded. Plasma levels of apo E are modestly increased in humans with heterozygous familial hypercholesterolemia 30 and may be increased several-fold in human homozygotes (Havel, Bilheimer, Kane, Kotite, and Hamilton, unpublished observations, University of California School of Medicine, San Francisco, California, 1982).…”

Determination of Human Apolipoproteins A-I, B, and E by Laser Nephelometry

“…Distinctly elevated apolipoprotein E concentrations in type III hyperlipoproteinaemia have been demonstrated in all reports (22,(37)(38)(39)(40)). An incomplete catabolism of triglyceride-rich lipoproteins or unusual synthetic products may account for a slight increase of serum apolipoprotein E levels in other forms of hyperlipoproteinaemia (22,37,39).…”

“…An incomplete catabolism of triglyceride-rich lipoproteins or unusual synthetic products may account for a slight increase of serum apolipoprotein E levels in other forms of hyperlipoproteinaemia (22,37,39). Because of the fact that the ultracentrifugation procedure results in the appearance of considerable amounts of apolipoprotein E in the lipoprotein-free fraction of serum (22,39), a discrimination into VLDL-and HDL-associated apolipoprotein E is problematic. In agreement with Carlson & Holmquist (40) no significant relationships could be observed between serum or lipoprotein lipids and apolipoprotein E.…”