High density lipoprotein particle size distribution in cord blood

Cord blood from 73 full term healthy newborns and blood from adults were analysed for the protein content of high density lipoprotein subclasses separated by gradient gel electrophoresis. Cholesterol and triglyceride concentrations of very low (VLDL), low (LDL) and high (HDL) density lipoproteins were also analysed and newborns had lower concentrations of cholesterol and triglycerides in VLDL, LDL and HDL (p less than 0.001) than adults. The HDL3c subclass, comprising the smallest particles of the HDL particle spectrum, was the major component for newborns and the minor one for adults and was the only lipoprotein fraction with a higher concentration in cord than in adult blood. No sex differences were present for any of the lipoprotein levels of the newborns. Serum cholesterol concentrations were positively correlated to HDL2b (r = 0.49, p less than 0.001) and HDL2a levels (0.42, p less than 0.001), correlations confined to the cholesterol contents of HDL (r = 0.72 and r = 0.67 respectively, both p less than 0.001). Serum triglycerides were inversely correlated to HDL2b and HDL2a levels in male newborns only (r = 0.38 and r = 0.34 respectively, both p less than 0.05). Irrespective of sex, gestational age and birthweight the newborns had 2 typical HDL subclass distributions, characterized by high or low levels of HDL2b and HDL2a. The newborns with high HDL2b and HDL2a levels also had low VLDL lipid levels and high HDL cholesterol concentrations.