MODIFICATION OF PLATELET-AGGREGATION BY LEUKOCYTES IN ACUTE ISCHEMIC STROKE

Background and Purpose Platelet aggregation plays an important role in the pathogenesis of thromboembolic cerebrovascular disease. Leukocyte s can efficiently stimulate as well as inhibit platelet aggregability. We studied the influence of leukocytes on collagen-induced platelet a ggregation in patients with acute ischemic stroke. Methods We investig ated 23 patients within 2 days after stroke and 23 healthy age- and se x-matched control subjects and determined collagen-induced platelet ag gregation in platelet-rich plasma with or without addition of polymorp honuclear or mononuclear leukocytes. Results Platelet aggregation with out leukocytes tended to be lower in patients than in control subjects (P=.06). Mononuclear leukocytes reduced (P=.018) and polymorphonuclea r leukocytes tended to reduce (P=.06) platelet aggregation in patients . Leukocytes did not significantly alter platelet aggregation in contr ol subjects. In the presence of either mononuclear or polymorphonuclea r leukocytes, platelet aggregation was significantly lower in patients than in control subjects (P=.004 and P=.008). The ratio of polymorpho nuclear leukocytes to platelets in venous blood was higher in patients than in control subjects (P<.001). Conclusions Mononuclear-and less c learly polymorphonuclear-leukocytes possess a platelet aggregation-inh ibiting potential in the early stages after ischemic stroke, a feature with possible antithrombotic effects.