title: LpA-I levels do not reflect pre beta1-HDL levels in human plasma.
abstract: High-density lipoprotein (HDL) containing apo A-I but no apo A-II (LpA-I) can promote cholesterol efflux from cells, while HDL containing apo A-I and apo A-II can not. Pre beta1-HDL, a minor fraction of LpA-I, is the initial acceptor of cellular cholesterol. To determine whether the pre beta1-HDL:LpA-I ratio is constant in human plasma, we measured LpA-I levels by differential electroimmunoassay, and HDL subfraction levels by nondenaturing 2-dimensional gel electrophoresis in 26 subjects. We found that the pre beta1-HDL:LpA-I ratio was higher in hypercholesterolemia (0.21+/-0.09; n = 11, P < 0.05), coronary artery disease (0.26+/-0.13; n = 5, P = 0.08) and hypertriglyceridemia (0.39+/-0.22; n = 3, P = 0.16) than in normolipidemia (0.11+/-0.03, n = 5). LpA-I levels were significantly correlated with HDL2b (r = 0.771, P=0.000001), HDL2a (r = 0.438, P < 0.01), and pre beta2-HDL levels (r = 0.496, P < 0.005) but not with pre beta1-HDL or HDL3 levels. In conclusion, the pre beta1-HDL:LpA-I ratio is not constant in human plasma. These findings strongly suggest that size distribution of LpA-I may change in various disorders.
authors.affiliation: Department of Laboratory Medicine, Niigata University School of Medicine, Asahimachi, Japan. miida@med.niigata.u.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Miida
authors.forename: K
authors.initials: K
authors.lastname: Inano
authors.forename: T
authors.initials: T
authors.lastname: Yamaguchi
authors.forename: T
authors.initials: T
authors.lastname: Tsuda
authors.forename: M
authors.initials: M
authors.lastname: Okada
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016632:Apolipoprotein A-I / Q000097:blood*; D002469:Cell Separation; D003327:Coronary Disease / Q000097:blood / Q000503:physiopathology; D015180:Electrophoresis, Gel, Two-Dimensional; D005260:Female; D053442:High-Density Lipoproteins, Pre-beta; D006801:Humans; D006937:Hypercholesterolemia / Q000097:blood / Q000503:physiopathology; D006949:Hyperlipidemias / Q000097:blood / Q000503:physiopathology; D015228:Hypertriglyceridemia / Q000097:blood / Q000503:physiopathology; D008075:Lipoproteins, HDL / Q000097:blood* / Q000737:chemistry / Q000302:isolation & purification; D053439:Lipoproteins, HDL2; D008297:Male; D008875:Middle Aged
chemical_list: D016632:Apolipoprotein A-I; D053442:High-Density Lipoproteins, Pre-beta; D008075:Lipoproteins, HDL; D053439:Lipoproteins, HDL2