OXIDIZED LOW-DENSITY LIPOPROTEINS STIMULATE ADHESION OF MONOCYTES TO ENDOTHELIAL-CELLS

AIM: To study the effects of oxidized low-density lipoproteins (ox-LDL ) on the adhesiveness of monocytes to endothelial cells. METHODS: LDL was obtained from healthy human plasma by ultracentrifugation, and oxi dized by CuSO4 10 mu mol . L(-1). The assay of adhesion was performed using cultured bovine aortic endothelial cells (BAEC) and human periph eral blood monocytes. RESULTS: Pretreatment BAEC with ox-LDL enhanced monocyte adhesion to BAEC in time- and dose-dependent manner. ox-LDL a s little as 10 mg . L(-1) and 30 min of preincubation stimulated monoc yte adhesion. Cycloheximide (Cyc, a protein synthesis inhibitor) 1 mg . L(-1) and staurosporine (Sta, a PKC inhibitor) 20 nmol . L(-1) aboli shed the effect of ox-LDL (60 mg . L(-1)), but dextran sulfate 20 mg . L(-1) had no effect on monocyte adhesion. Phorbol 12-myristate 13-ace tate (PMA) 1 nmol . L(-1) and lysophosphatidylcholine (Lys) 6 mu mol . L(-1) mimicked the effects of ox-LDL and potentiated monocyte adhesio n. Sta also suppressed the augmentative effects of Lys and PMA. CONCLU SION: ox-LDL enhances the adhesion of monocytes to BAEC through the ac tivation of PKC.