Flow cytometry demonstrates differences in platelet reactivity and microparticle formation in subjects with thrombocytopenia or thrombocytosis due to primary haematological disorders.

Background: Traditional methods for the assessment of platelet function require a minimum number of platelets. As flow cytometry is independent of platelet number, we measured platelet activation and microparticle formation in thrombocytopenia and thrombocytosis.

Materials And Methods: Blood was obtained from normal subjects or subjects with immune thrombocytopenic purpura (ITP), myelodysplasia (MDS) or essential thrombocythaemia (ET). Platelet activation and microparticle formation were assessed in resting and agonist stimulated samples.

Results: Platelet activation was significantly decreased in MDS in agonist-stimulated platelets when compared to normals and ITP, however increased microparticle-to-platelet ratios were found. Absolute platelet-derived microparticle counts were significantly higher in ET when compared to normals, but there was no significant difference in microparticle-to-platelet ratios between ET and normals.

Conclusions: Decreased platelet activation was demonstrated in MDS when compared to normal subjects and ITP. Platelet-derived microparticle counts are increased in ET, reflecting increased platelet counts rather than an increase in platelet reactivity. Flow cytometric analysis of platelets may aid the diagnosis and management of these conditions.