Concentrations of electrophoretic and size subclasses of apolipoprotein A-I-containing particles in human peripheral lymph.
When cultured cells are exposed to plasma, the initial acceptors of unesterified cholesterol are small lipid-poor apolipoprotein A-I (apoA-I)-containing high density lipoproteins (HDLs) with pre-beta electrophoretic mobility. These are converted by lecithin:cholesterol acyltransferase into larger spheroidal cholesteryl ester-rich HDLs with alpha mobility. To study the determinants of the concentration of small pre-beta HDLs in tissue fluids, we collected prenodal peripheral lymph from 34 fasted normal men. By crossed immunoelectrophoresis, the concentration of pre-beta HDLs in lymph averaged 20% of that in plasma. On multiple regression analysis, pre-beta apoA-I concentration in lymph was directly related to pre-beta apoA-I concentration in plasma and independently to alpha apoA-I concentration in lymph. Similar results were obtained when the same apoA-I-containing particles were quantified by size exclusion chromatography. Lymph pre-beta apoA-I concentration was low in a subject with familial lecithin:cholesterol acyltransferase deficiency, despite a normal plasma pre-beta apoA-I concentration, but was normal in a subject with familial lipoprotein lipase deficiency. These results suggest that the concentration of small pre-beta HDLs in human tissue fluids is determined only in part by the transfer of pre-beta HDLs across capillary endothelium from plasma. Local production, by remodeling of spheroidal alpha HDLs in tissue fluids, may be equally important. Lipolysis of triglyceride-rich lipoproteins by lipoprotein lipase appears to have little effect.
Nanjee
M N
MN
Department of Cardiovascular Biochemistry, St Bartholomew's and the Royal London School of Medicine and Dentistry, London, UK.
Cooke
C J
CJ
Olszewski
W L
WL
Miller
N E
NE
D000328:Adult; D016632:Apolipoprotein A-I / Q000737:chemistry* / Q000145:classification / Q000378:metabolism; D002850:Chromatography, Gel; D006801:Humans; D008072:Hyperlipoproteinemia Type I / Q000378:metabolism; D007122:Immunoelectrophoresis; D008196:Lymph / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010316:Particle Size; D007862:Phosphatidylcholine-Sterol O-Acyltransferase / Q000378:metabolism
D016632:Apolipoprotein A-I; D007862:Phosphatidylcholine-Sterol O-Acyltransferase