We investigated the association of β2-glycoprotein I and P-selectin with platelet-derived microparticles in 48 patients with immune thrombocytopenic purpura and 20 normal controls using two-color flow cytometric analysis. In addition, anticardiolipin antibodies were detected by an enzyme-linked immunosorbent assay. Platelet microparticles from the patients showed a higher positivity for β2-glycoprotein I than those from the normal controls (23.1±15.4% vs. 5.3±3.1%, p<0.01), but this positivity was not related to the presence of platelet-associated IgG or to the severity of thrombocytopenia. In the 18 patients with more than 20% P-selectin-positive microparticles, β2-glycoprotein I positivity was significantly higher than in the 30 patients with less than 20% P-selectin-positive microparticles (37.1±20.5% vs. 21.5±17.3%, p<0.01). In addition, anticardiolipin antibodies were detected in eight patients, and they had a significantly higher level of β2-glycoprotein I-positive microparticles than the patients without such antibodies (42.0±22.9% vs. 22.6±18.9%, p<0.05). Our results suggest that anticardiolipin antibodies activate platelets in immune throm bocytopenic purpura and cause the generation of microparticles rich in β2-glycoprotein I and P-selectin. These microparticles may then act to regulate coagulation abnormalities in patients with anticardiolipin antibodies.
- Anticardiolipin antibody P-selectin
- Immune thrombocytopenic purpura Microparticle
- β-glycoprotein I
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