Characterization and quantification of serum lipoprotein subfractions by capillary isotachophoresis: relationships with lipid, apolipoprotein, and lipoprotein levels

Human serum lipoproteins are currently defined according to their density a s well as according to their electrophoretic mobility. They can be fraction ated into discrete subspecies which exhibit variations in their structure a nd function. Capillary electrophoresis has been suggested to be a potential analytical strategy in understanding metabolic Lipoprotein heterogeneity, In a sample of 35 normolipidemic subjects, we analyzed ceramide-labeled ser um lipoproteins by capillary isotachophoresis linked to laser-induced fluor escent detection. Capillary isotachophoresis shelved advantage to be an aut omated, rapid (6 min) and reproducible (CV < 7%) separation mode, on-line m onitoring lipoprotein subfractions according to net charge. HDL were separa ted into three subfractions: i) the fast migrating HDL correlated positivel y with serum apoA-I (P < 0.05) and negatively with triglyceride (P < 0.01) concentrations, ii) the intermediate migrating HDL involved in HDL-choleste rol delivery and inversely related to LDL particles concentration (P < 0.00 1), and iii) the slow migrating pre beta(1)-HDL, Triglyceride level was sig nificantly associated with two fractions: i) the VLDL fraction correlated p ositively with apoE serum concentration (P < 0.01), and ii) the IDL fractio n closely and positively associated with apoC-III-containing Lipoprotein le vel (P < 0.001), Two LDL subfractions were positively related to LDL-choles terol (0.05 less than or equal to P < 0.01) and might characterize, respect ively, small dense and large buoyant LDL subfractions: i) the fast migratin g LDL, positively linked to apoB concentration and to LpCIII:B (P < 0.01) r eflecting altered IDL metabolism, and ii) the slow migrating LDL.Analytical capillary isotachophoresis of fluorescent-stained lipoprotein subfractions might represent an efficient qualitative and quantitative tool which would afford complementary information on lipoprotein metabolism to current clin ical Lipoprotein analysis.