Platelet Function in Essential Thrombocythemia

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Abstract
Platelets from two patients with essential thrombocythemia failed to aggregate or release serotonin in response to concentrations of epinephrine that aggregated platelets from normal controls. Therefore, we studied their α-adrenergic receptors, using 3H-dihydroergocryptine (3H-DHE), an α-adrenergic antagonist. These platelets contained an average (mean ± S.E.) of 210±18 and 227±27 3H-DHE binding sites per platelet — less than half that found on control platelets, 464±37 (P3H-DHE sites. Platelets in essential thrombocythemia demonstrated normal kinetics of 3H-DHE binding and normal affinities for 3H-DHE and for epinephrine. When control platelets were preincubated with a half-saturating concentration of 3H-DHE, there was a diminution of epinephrine-induced platelet function comparable to that seen in essential thrombocythemia. Thus, a deficiency of α-adrenergic receptors may account for diminished functional responsiveness of platelets to epinephrine in some patients with essential thrombocythemia. (N Engl J Med 299:505–509, 1978)