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Antiphospholipid antibody‐dependent C5b‐9 formation
Author(s) -
Stewart Michael W.,
Etches Wai S.,
Gordon Philip A.
Publication year - 1997
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1046/j.1365-2141.1997.d01-2067.x
Subject(s) - properdin , platelet , antibody , complement system , chemistry , complement membrane attack complex , flow cytometry , monoclonal antibody , immunology , microbiology and biotechnology , biology
The relationship between the presence of antiphospholipid antibodies (APA) and the production of the terminal membrane attack complex (MAC) of complement (C5b‐9) was studied. Serum samples from known high positive APA patients induced platelet activation and destruction which was inhibited by heat‐inactivation of the sera. The response was restored if the heat‐inactivated APA‐positive sera were supplemented with normal sera. Adsorption of the APA‐positive sera with phospholipid (PL)‐coated polystyrene beads inhibited platelet destruction. Addition of monoclonal antibody (mAb) to C5b‐9 (aE11) also inhibited platelet destruction, suggesting that the APA‐dependent platelet destruction might be complement‐mediated. Purified APA, in the presence of normal serum, induced C5b‐9 formation and binding to PL‐coated beads in a dose‐dependent manner as detected by flow cytometry. Prospective analysis of 200 serum samples for C5b‐9 production showed that all sera testing negative for the presence of APA also tested negative for C5b‐9 production. All sera with high levels of IgG binding to PL (GPL) showed evidence of C5b‐9 production. Sera with low or moderate GPL values showed varying levels of C5b‐9 production. These data suggest that complement may play a key role in APA‐dependent platelet activation, in vivo .