Slow beta-migrating lipoprotein: an atherogenic subclass of low density lipoproteins.

OBJECTIVE

To clarify the possibility that midband Lp in LDL fractions might act as an atherogenic lipoprotein in their interaction with macrophages.

DESIGN AND METHODS

Low density lipoproteins (LDL) isolated by zonal ultracentrifugation from midband lipoprotein-positive serum in type lib hyperlipidemics were subjected to polyacrylamide gel disc electrophoresis.

RESULTS

A part of midband lipoprotein was observed between pre beta-and beta-band, in addition to the main beta-band. We named this midband lipoprotein "slow beta-migrating Lp (slow beta-Lp)." The larger LDL subfraction from midband-lipoprotein positive serum on Sepharose 2B column chromatography contained much slow beta-Lp, named slow beta-Lp-rich LDL. The smaller LDL subfraction contained a little slow beta-Lp, named slow beta-Lp-poor LDL. Slow beta-Lp-rich LDL had similar composition to the control LDL except for apolipoprotein E. The uptake of [3H]cholesteryl linoleate-labeled slow beta-Lp-rich LDL by J774 macrophages was higher than that of control LDL. The cholesterol ester content of J774 macrophages incubated with slow beta-Lp-rich LDL increased significantly compared with slow beta-Lp-poor LDL, beta-VLDL, and control LDL.

CONCLUSION

These results suggest that slow beta-Lp in type llb might generate foam cells from macrophages in atherosclerotic lesions.