Anti-phospholipid antibodies bind to platelet microparticles in idiopathic (autoimmune) thrombocytopenic purpura.
We recently reported that IgM antibody-related microparticles exist in some patients with idiopathic thrombocytopenic purpura (ITP) [14]. In this study, we investigated the relationship between antiphospholipid (cardiolipin and phosphatidylinositol) antibodies and microparticles in 56 ITP patients. We used an ELISA to detect anti-phospholipid antibodies. IgG antibodies against cardiolipin and phosphatidylinositol were detected in 13 and 12 patients, respectively. The titers of IgG antibodies against these phospholipids did not correlate with the platelet-associated IgG level or the platelet count. Next, we investigated the binding of anti-phospholipid antibodies to platelets and microparticles. Microparticles were obtained by incubating washed platelets with collagen plus thrombin. ITP plasma containing IgG-class anti-phospholipid antibodies showed significantly increase binding to microparticles compared with plasma without such antibodies (p less than 0.001). Our results suggest that anti-phospholipid antibodies could affect the function of platelet microparticles in ITP.
Nomura
S
S
First Department of Internal Medicine, Kansai Medical University, Osaka, Japan.
Yanabu
M
M
Fukuroi
T
T
Kido
H
H
Kawakatsu
T
T
Yamaguchi
K
K
Suzuki
M
M
Kokawa
T
T
Yasunaga
K
K
D000906:Antibodies / Q000276:immunology*; D001792:Blood Platelets / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000276:immunology; D010316:Particle Size; D010743:Phospholipids / Q000276:immunology*; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000097:blood / Q000276:immunology*; D012016:Reference Values
D000906:Antibodies; D010743:Phospholipids