Objectives--Experiments in cells and animal models show that lipoprotein lipase (LpL) bound to apolipoprotein (apo)B lipoproteins enhances their uptake by receptor mediated pathways. It is unknown whether this pathway is important in humans.

Methods and Results--apoB lipoproteins with LpL were isolated from normal subjects after oral fat loading by immunoaffinity chromatography and were further separated into apoB100 and apoB48 lipoproteins. Postprandially, apoB lipoproteins with LpL had significantly greater increases (4- to 10-fold) and faster rates of clearance (5- to 8-fold) percentage-wise than those without LpL. apoB lipoproteins with LpL had enhanced clearance regardless of whether they also contained apoE. LpL was particularly important for the clearance of apoB48 lipoproteins, of which 25% (range, 11% to 31%) could be removed from circulation together with LpL during the postprandial state. apoB lipoproteins with LpL were larger in size and were enriched in triglyceride, cholesterol, and apoE compared with those without LpL. However, neither size nor apoE content explained the faster clearance rates of LpL-containing lipoproteins.

Conclusion--Plasma LpL may act like an apolipoprotein to enhance the clearance of apoB lipoproteins in humans, a mechanism particularly important for intestinal lipoproteins in the postprandial state.