Pathogenetic analysis of five cases with a platelet disorder characterized by the absence of thromboxane A2 (TXA2) -induced platelet aggregation in spite of normal TXA2 binding activity
Fuse, I.; Hattori, A.; Mito, M.; Higuchi, W.; Yahata, K.; Shibata, A.; Aizawa, Y.
Thrombosis and Haemostasis 76(6): 1080-1085
1996
ISSN/ISBN: 0340-6245 PMID: 8972034 Document Number: 457670
Five patients with mild bleeding tendencies characterized by defective thromboxane A-2 (TXA-2)-induced platelet aggregation are reported. The platelets of all the patients had the ability to bind exogenous TXA-2. Bleeding time was markedly prolonged in one patient. In three of the five patients, synthetic TXA-2 mimetic (STA-2)-induced platelet responses, including IP-3 formation, Ca-2+ mobilization, phosphatidic acid formation and GTPase activities were selectively defective, suggesting impaired coupling between the TXA-2 receptor and phospholipase C activation. However, in the remaining two patients, these responses were all within normal limits. This suggests that the defective site of this type of platelet disorder is heterogenous and that signaling mechanisms other than the TXA-2 receptor-phospholipase C pathway are also involved in TXA-2-induced platelet aggregation.