Binding of Platelet-Activating Factor to Platelets of Ischemic Stroke Patients

Platelet-activating factor (PAF) has been suggested to play an important role in brain ischemia and stroke. We examined whether binding of PAF to platelets of patients suffering from ischemic stroke differs in the acute and subacute stages, and correlated the results with the severity of neurological presentation. A total of 30 patients with first ever ischemic stroke was studied. The patients were divided into two groups according to stroke severity as assessed by the Scandinavian Stroke Scale (SSS). Binding of PAF to platelets was performed on admission (first determination) and 3 weeks later (second determination) by labeling with [H]PAF. Results of PAF binding were obtained also from 21 healthy age- and sex-matched volunteers. Binding results shortly after stroke onset were significantly lower in the severely affected group (analysis of variance, F = 11.0, p < .001). Moreover, only in these patients was there a change in PAF binding between the first and the sec-nd determinations (Wilcoxon signed ranks test, p = .018). A significant correlation was found between PAF binding and severity of neurologic deficits as assessed by the SSS (correlation coefficient = .52, p = .01). This result shows evidence of PAF system involvement in stroke patients. PAF binding to platelets clearly differs in the acute and subacute stages, and the reduction in the number of binding sites correlates with severity of neurologic deficits. We conclude that PAF binding in platelets may serve as an additional marker of stroke severity.