Radioimmunoassay of human plasma lecithin-cholesterol acyltransferase.
A sensitive and precise competitive-displacement double-antibody radioimmunoassay was developed for the human plasma enzyme lecithin-cholesterol acyltransferase (LCAT; Ec 2.3 1.43). The ability of plasma from various animal species to displace labeled human LCAT from goat anti-human LCAT could be ranked in the following order: man and sheep > nonhuman primates > cat or dog > pig > rabbit or guinea pig > mouse > rat. Normolipidemic subjects had levels of LCAT of 6.14 +/- 0.98 micrograms/ml (mean +/- SD, n = 66). Subjects with dysbeta-lipoproteinemia had the highest plasma LCAT levels (7.88 +/- 0.39 micrograms/ml, n = 7, P < 0.05), followed by hypercholesterolemic subjects (7.00 +/- 1.30, n = 41) and hypertriglyceridemic subjects (6.96 +/- 1.3, n = 10). LCAT-deficient subjects had the lowest enzyme levels (0.89, 0.83, and 0.05 micrograms/ml, respectively, and two subjects with no detectable enzyme).  Males had lower LCAT levels (6.42 +/- 1.05 micrograms/ml, n = 90, for all subjects; 5.99 +/- 1.03, n = 44, for normolipidemics) than females (7.01 +/- 1.14, n = 34, for all subjects P < 0.01; 6.44 +/- 0.79, n = 22, for normolipidemics, P < 0.01). LCAT levels correlated significantly with total cholesterol (males, r = 0.384, P < 0.001; females, r = 0.519, P < 0.002); and total triglyceride (only in females, r = 0.512, P < 0.002). LCAT levels in females correlated inversely with HDL cholesterol (r = 0.341, P < 0.05) and apoprotein D (r = 0.443, P < 0.02), but no such relationship existed in males.
D000818:Animals; D001793:Blood Preservation; D001798:Blood Proteins / Q000032:analysis; D005260:Female; D005615:Freezing; D000882:Haplorhini / Q000097:blood; D006801:Humans; D006949:Hyperlipidemias / Q000201:enzymology; D007863:Lecithin Cholesterol Acyltransferase Deficiency / Q000201:enzymology; D008055:Lipids / Q000097:blood; D008297:Male; D007862:Phosphatidylcholine-Sterol O-Acyltransferase / Q000097:blood*; D010949:Plasma / Q000201:enzymology; D011863:Radioimmunoassay; D012756:Sheep / Q000097:blood
D001798:Blood Proteins; D008055:Lipids; D007862:Phosphatidylcholine-Sterol O-Acyltransferase