High-density lipoprotein subclass distribution in premature newborns before and after the onset of enteral feeding.

Changes in high-density lipoprotein (HDL) subclass distribution were evaluated in a group of premature infants during the early postnatal period to ascertain whether enteral feeding brought about a rapid shift from neonatal to adult-like distributions. All infants were fed a combination of breast milk and formula. Cord blood of premature infants had a predominance of large, less dense (HDL2b)gge and a paucity of intermediate-sized (HDL3a)gge particles. Lack of a peak in the (HDL3a)gge is a characteristic feature for cord blood, whereas a prominent (HDL3a)gge peak is characteristic of adult plasma. After the start of enteral feeding, blood was obtained at two time-points: 6-14 days (sample A) and 17-32 days (sample B) postdelivery. With the onset of feeding, triglyceride increased significantly from an average of 34 mg/dl in cord blood to 120 mg/dl in sample B, and cholesterol increased from 86 to 112 mg/dl in the same period. Increases in plasma lipid concentrations were paralleled by a redistribution of subclasses such that three components of almost equal intensity were evident in sample B; these consisted of (HDL2b)gge, (HDL2a2)gge, and (HDL3b)gge. A paucity of (HDL3a)gge particles persisted even after onset of enteral feeding; thus, increases in plasma triglyceride and cholesterol per se are not sufficient to induce the adult-like distribution. It is suggested that development of the normal adult HDL subclass pattern is complex and is probably related to the development and interaction of several factors, including plasma enzymes involved in lipid hydrolysis and esterification, lipid exchange proteins, and hormonal status.