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Updated: Sep 27, 2026

Procoagulant Platelet Characterization by Measuring Phosphatidylserine Exposure and Microvesicle Release from Human Purified Platelets
Published on: November 29, 2024
Cyclic-AMP agonists inhibit antiphospholipid/beta2-glycoprotein I induced synthesis of human platelet thromboxane A2
Reginald Opara1, Dick L Robbins, Vincent A Ziboh
1Department of Dermatology, School of Medicine, University of California at Davis, 95616, USA.
Objective:
To investigate mechanisms responsible for increased thrombotic activity in systemic lupus erythematosus (SLE) associated with the antiphospholipid syndrome (APS). We had reported that anticardiolipin/beta2-glycoprotein I (aCL/beta2-GPI) complexes induce platelet overactivity resulting in excessive production of thromboxane A2 (TXA2). Presumably this occurs by decreased platelet cyclic AMP (cAMP) activity and results in increased platelet aggregation.
Methods:
We stimulated platelet intracellular cAMP generation with known cAMP agonists (dibutyryl cAMP, theophylline, and prostaglandin E1) and measured aCL/beta2-GPI induced platelet TXB2 production in vitro. Isolated human platelets were prelabeled with 14C-arachidonic acid and then challenged with aCL/beta2-GPI in the presence or absence of cAMP-activating substances. The resulting 14C labeled TXB2 was quantified by thin layer chromatography and radioactive scanning.
Results:
We found a marked decrease in aCL/beta2-GPI induced platelet TXB2 production by the cAMP agonists in a dose dependent manner.
Conclusion:
Our findings suggest the usefulness of cAMP agonists in the control of thrombosis in some patients with SLE and APS.
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