Journal of Lipid Research, Vol 29, 121-135, Copyright © 1988 by Lipid Research, Inc.
High density lipoprotein particle size distribution in subjects with obstructive jaundice
PM Clifton, PJ Barter and AM Mackinnon
Department of Medicine, Flinders University of South Australia, Bedford Park.
High density lipoproteins (HDL) from 14 patients with obstructive jaundice
were examined by gradient gel electrophoresis to determine the effect of
obstruction on particle size distribution. HDL from 7 of these patients
were fractionated by gel permeation chromatography and further
characterized by electron microscopy, SDS gel electrophoresis,
apolipoprotein A-I and apolipoprotein A-II immunoturbidimetry, and analysis
of chemical composition. In addition, lecithin:cholesterol acyltransferase
(LCAT) activity was measured and correlated with plasma apolipoprotein A-I
concentration and particle size distribution. HDL were abnormal in all
patients regardless of severity, cause, or duration of obstruction. The
major HDL subfraction in normal subjects, HDL3a (radius 4.1-4.3 nm) was
either absent or considerably diminished, and HDL2b (radius 5.3 nm) was
also frequently absent. Very small particles comparable in size to normal
HDL3c (radius 3.8 nm) were prominent. In patients with a bilirubin
concentration greater than 250 mumol/l, normal HDL had totally disappeared
and were replaced by large discoidal particles of radius 8.5 nm and small
spherical particles of radius 3.6-3.7 nm. Both populations of particles
were markedly depleted of cholesteryl ester and enriched in free
cholesterol and phospholipid. The discoidal particles were rich in
apolipoproteins E, A-I, A-II, and C, while the small spherical particles
contained predominantly apolipoprotein A-I. LCAT activity was diminished in
all subjects to 8- 54% of normal, and was strongly positively correlated (r
= 0.91 P less than 0.05) with plasma apolipoprotein A-I levels.