Enhancement of monocyte adhesion to endothelial cells by oxidatively modified low-density lipoprotein is mediated by activation of CD11b.

Treatment of human peripheral blood monocytes with oxidized (oxLDL), minimally modified low-density lipoprotein (mmLDL) or lysophosphatidylcholine (LPC) for 24h was associated with macrophage-like differentiation, as assessed by morphology/CD14 expression. Suppression of these effects by staurosporin (STS) indicated the dependence on protein kinase C (PKC) activation. OxLDL and mmLDL increased monocyte adhesion to human umbilical vein endothelial cells 2-fold. Enhancement of adhesion was prevented by an anti-CD11b mAb, demonstrating the involvement of CD11b. While LPC increased monocyte adhesion, inhibition of PKC by STS reversed enhancement of adhesion by oxLDL, showing mediation by LPC-induced PKC activation. OxLDL, mmLDL or LPC increased CD11b expression and stimulated a distinct peak in fluorescence intensity, suggesting that CD11b activation was crucial for enhanced monocyte adhesion.