The lipoproteins of human umbilical cord blood apolipoprotein and lipid levels.

The levels of apolipoproteins B, E and A-1 and the molecular species of triacylglycerols, phospholipids and cholesteryl esters were individually quantitated by electroimmunoassay and gas chromatographic total lipid profiling in 50 fresh samples of umbilical cord sera obtained from full term, normal delivery, healthy human neonates. All samples were screened for IgA to eliminate those samples with maternal blood contamination. The whole serum apolipoprotein levels in mg/dl +/- SEM for all neonates were; Apo B = 25.4 +/- 1.2; Apo E = 5.0 +/- 0.3; Apo A-1 = 86.6 +/- 2.3. These values represented 25% and 60% of adult serum values for Apo B and A-1, respectively, with normal adult values for Apo E. Apo A-1 was higher (P less than 0.020) in sera from female when compared to male neonates. The whole serum lipid values in mg/dl +/- SEM for all neonates were: 20.8 +/- 2.0 for triacylglycerols; 74.2 +/- 2.6 for lecithin and sphingomyelin; 79.8 +/- 2.7 for cholesteryl esters and 20.4 +/- 0.8 for unesterified cholesterol. Phospholipids, cholesteryl esters and total cholesterol levels were higher (P less than 0.025) in sera from female neonates when compared to males. The proportion of unesterified cholesterol relative to cholesteryl esters was high in comparison to adult sera, however the total cholesterol to phospholipid ratios were similar. The molecular species of cord sera triacylglycerols indicated a decreased proportion of C16 fatty acids with increased C18 and C20 when compared to adult sera. The molecular species of cord sera phospholipids similarly contained a decreased proportion of C16/18 fatty acids with increased C18/20 or C16/22 fatty acid combinations when compared to adults. The cord sera cholesteryl esters contained a significantly higher proportion of cholesterol esterified to C16 fatty acids with decreased amounts of cholesterol esterified to C18 and C20 fatty acids when compared to adults. Good correlations were obtained between Apo B and total serum cholesterol (R = 0.77) and also between Apo B and total serum triacylglycerols (R = 0.78).