| Budget Amount *help |
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 1999: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1998: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
The primary aims of this study are to identify epitopes recognized by antiphospholipid monolconal autoantibodies established from (NZW X BXSB) FィイD21ィエD2 mice with antiphospholipid syndrome (APS), and clarify mechanisms of antibody-mediated pathological thrombosis. In addition, we examined the platelet-membrane flip-flop translocates phosphatidylserine (PS) or cardiolipin (CL) in cells from the inside to outside in patients with APS or healthy controls. Identification of epitopes recognized by antiphospholipid monolconal autoantibodies (aPL) : In this study, we succeeded to establish six monoclonal antibodies (mAb) against cardiolipin (CL) derived from (NZW X BXSB) FィイD21ィエD2 mice with APS. Of the 6 mAb against CL, 2 clones recognized βィイD22ィエD2 -glycoprotein I (β2GPI), and also these 2 clones cross-reacted with the oxidative form of low-density lipoproteins (ox-LDL). β2GPI, also known as the complement control protein (CCP) consists of five consensus repeat domains, is a plasma glycop
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rotein with anticoagulant activity. To identify the epitope on β2GPI recognized by aCL, we established five deletion mutants of β2GPI lacking each of consensus repeat domains. Interestingly, mAb failed to bind to all of five mutants, suggesting that these mAb recognize the conformational epitopes consist of five consensus repeat domains.
Analysis of the membrane flip-flop of platelets derived from patients with APS : It has been known that the binding of phospholipid-binding protein (PBP) such as β2GPI or annexin V to phospholipids (especially, PS or CL) translocated to the outside of platelet membrane, is important for aPL-mediated thrombosis. These phospholipids are usually located at the inside leaf of the bilayer membrane in an intact platelet. We examined the membrane flip-flop of platelets derived from APS patient or healthy controls in the presence of some agonists. Slightly increased membrane flip-flop was found in patients with APS compared with controls. suggesting that aCL/β2GPI complexes may contribute to platelet activation through Fc receptors. Less
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