Reduction of monocyte-platelet interaction and monocyte activation in patients receiving antiplatelet therapy after coronary stent implantation

BACKGROUND: Monocyte activation induces different procoagulant and proadhesiveinflammatory responses and thus may play a role in thromboticcomplications after coronary interventions. Monocyte-plateletinteraction may trigger these effects inducing monocyte activation. AIMS: To characterize the effect of antiplatelet vs anticoagulationtherapy on monocyte-platelet interaction and monocyte functionafter intracoronary stenting. METHODS AND RESULTS: Immediately before, and during the first 12 days after successfulcoronary stenting, monocyteplatelet conjugates and monocytefunction were assessed by flow cytometric detection of GPIIb/IIIa(CD41) on monocytes and by monocyte surface exposure of Mac-1(CD11b/ CD18) and L-selectin (CD62L). Twenty patients receivingcombined antiplatelet therapy (ticlopidine, aspirin) were comparedto 20 patients with standard anticoagulation (phenprocoumon,overlapping heparin, aspirin). Before stenting, monocyte-plateletconjugates and Mac-1 surface expression in both groups weresignificantly increased, while L-selectin was significantlydiminished. Anticoagulation did not change these variables significantlyduring the subsequent 12 days. In contrast, antiplatelet therapyreduced platelet-monocyte conjugates by 46±9·3%(mean±SEM, P=0·0019) within 4 days, which wasassociated with a decrease in Mac-1 expression (28±6·7%,P=0·0013) and an increase in L-selectin (56±15·0%,P=0·0061). CONCLUSION: After intracoronary stenting, combined antiplatelet therapy,but not anticoagulation, causes reduction of monocyte-plateletinteraction, which is associated with monocyte deactivation.This may contribute to a decreased risk for thrombotic events.