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Zuowei Su, Tomonori Izumi, Thomas L. Ortel
Prothrombin and 2-glycoprotein I frequently contribute to antiphospholipid antibody interactions with phospholipids and the generation of abnormal waveform profiles in coagulation assays
Transmittance waveforms are generated during clot formation on photo-optical coagulation analyzers. We previously showed that 61.5% of patients with antiphospholipid antibodies (APLA) exhibited a negative deflection in the pre-coagulation phase of the prothrombin time (PT slope 1). The current studies investigated the molecular basis of this abnormal parameter. We found that the negative PT slope 1 is IgG-mediated and is not dependent on the presence of fibrinogen or thrombin activity. We also found that IgG from most of the patients required a specific thromboplastin and the presence of prothrombin or 2-glycoprotein I 2 GPI) to produce an abnormal IgG wave-form assay. In addition, the abnormal IgG waveform required cofactor binding to phospholipids when 2 GPI was the cofactor, and annexin V could partially block this interaction. In conclusion, these results showed that the interactions of IgG with phospholipids via 2 GPI or prothrombin constitute the core mechanisms of the abnormal waveforms.
Thrombosis and Haemostasis, Schattauer
Print ISSN: 0340-6245
Volume: 90, 08/2003
Pages: 218 - 226