Relationship of microparticles with beta 2-glycoprotein I and P-selectin positivity to anticardiolipin antibodies in immune thrombocytopenic purpura.
We investigated the association of beta 2-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 beta 2-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, beta 2-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 beta 2-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 thrombocytopenic purpura and cause the generation of microparticles rich in beta 2-glycoprotein I and P-selectin. These microparticles may then act to regulate coagulation abnormalities in patients with anticardiolipin antibodies.
Nomura
S
S
First Department of Internal Medicine, Kansai Medical University, Osaka, Japan.
Yanabu
M
M
Miyake
T
T
Miyazaki
Y
Y
Kido
H
H
Kagawa
H
H
Fukuhara
S
S
Komiyama
Y
Y
Matsuura
E
E
Koike
T
T
D000293:Adolescent; D000328:Adult; D000368:Aged; D017153:Antibodies, Anticardiolipin / Q000276:immunology*; D001777:Blood Coagulation; D001792:Blood Platelets / Q000276:immunology* / Q000502:physiology / Q000648:ultrastructure; D002458:Cell Fractionation; D002462:Cell Membrane / Q000276:immunology / Q000502:physiology / Q000648:ultrastructure; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D006023:Glycoproteins / Q000032:analysis / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019007:P-Selectin; D010980:Platelet Membrane Glycoproteins / Q000032:analysis / Q000276:immunology*; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000097:blood / Q000276:immunology*; D053482:beta 2-Glycoprotein I
D017153:Antibodies, Anticardiolipin; D006023:Glycoproteins; D019007:P-Selectin; D010980:Platelet Membrane Glycoproteins; D053482:beta 2-Glycoprotein I