Defective Platelets in Essential Thrombocythemia

Abstract

Platelets from three consecutive patients with essential thrombocythemia were studied. In each case there were characteristic abnormalities. These included absent aggregation in response to epinephrine and reduced aggregation by adenosine diphosphate. The platelets were aggregated normally by collagen. Uptake by platelets of serotonin labeled with radioactive carbon¹⁴C was reduced, and there was possibly reduced platelet adenosine diphosphatase activity. The platelets supported normal clot retraction, and gave normal platelet factor 3 availability. The abnormality appears to be specific for the disease rather than a nonspecific reflection of thrombocythemia.