Increased platelet glycoprotein Ib receptor number, enhanced platelet adhesion and severe cerebral ischaemia in a patient with polycythaemia vera.

The present study describes severe multiplex cerebral ischaemic laesions in a male patient being diagnosed with polycythaemia vera (PV). In contrast to previous publications, unique platelet receptor pattern with normal platelet count was identified. Glycoprotein Ib receptor number on the surface of resting platelets was increased two-fold and almost three-fold in case of activated platelets compared to the controls. More over, in an in vitro study when whole blood was circulated both at venous and arterial shear conditions and shear rate was adjusted according to the blood viscosity, platelet aggregate/thrombus formation was characteristic on surfaces covered with purified von Willebrand factor while in case of controls the surface was covered with single platelets or platelet monolayer. Similar results with pathological findings have not been published in PV until now. Our result undersigns the necessity of antiplatelet therapy of PV patients, even at normal platelet count.