OXIDATIVE AND MALONDIALDEHYDE MODIFICATION OF LOW-DENSITY-LIPOPROTEIN- A COMPARATIVE-STUDY OF BINDING AND DEGRADATION BY MACROPHAGES AND ENDOTHELIAL-CELLS

Comparative study of oxidatively modified low-density lipoprotein (Ox- LDL) and malondialdehyde-modified low-density lipoprotein (MDA-LDL) is important for further understanding the biological properties of Ox-L DL, such as its toxic effects, immunogenicity and multiplicity of scav enger receptor binding. In this study, the characteristics of Ox-LDL a nd MDA-LDL binding and degradation were compared. The results show tha t when their degree of modification (as determined by relative electro phoretic mobility) was similar, the binding and degradation of Ox-LDL by the macrophage cell line P388D1 were greater than those of MDA-LDL. The binding and degradation of Ox-LDL by macrophages and human umbili cal vein endothelial cells increased with the degree of modification. In addition, Ox-LDL or MDA-LDL could competitively inhibit binding of labelled Ox-LDL or labelled MDA-LDL to their respective macrophage rec eptors, and could partially inhibit each other.