Platelet shape in primary platelet dysfunctions and shape change in response to agonists

Abstract

In order to clarify the relationship between the platelet shape and the disease abnormality, the circualting form and its change in response to agonists were examined in various primary platelet abnormalities. Patients consisted of thrombashenia (T) 3, essential athrombia (E) 2, Bernard-Soulier syndrome (BS) 1, May-Hegglin anomaly (MH) 2, Hermansky-Pudlak syndrome (HP) 1, platelet cyclo-oxygenase deficiency (CD) 1, release mechanism abnormality characterized by defective A23187-aggregation (A) 1, and aspirin-ingested volunteers (AS) . The circulating form was examined by our method using light microscopy. Shape change was induced by incubation of native platelet suspension from the subjects with various concentrations of either ADP (-10^-5M, 1min), thrombin (-2^-1U/ml, 30sec) or arachidonate (-2^-1mM, 2min).
Striking spherification and pseudopod formation were noted in circulating form in BS, a mild one in some of T and E, and a slight spherification in MH, whereas not in the others. Shape change induced by ADP was inhibited in none, and that by arachidonate was completely inhibited in CD (as previously reported ¹⁴), AS, HP and 2 out of 11 normal subjects. Thrombin-induced change was inhibited only in BS probably in agreement with its defect of glycoprotein Ib as a possible receptor of thrombin.
Thus the circulating form and its change response to some agonists differed among various platelet abnormalities. This indicates the necessities for clarifying the mechanism of shape change and for investigating clinical usefulness of shape (change) determination.