EPITOPES ON BETA-2-GPI RECOGNIZED BY ANTICARDIOLIPIN ANTIBODIES

Anticardiolipin antibodies (aCL) found in sera from patients with anti phospholipid syndrome recognize a cryptic epitope that appears on the beta 2-glycoprotein I (beta 2-GPI) molecule when beta 2-GPI interacts with a lipid membrane composed of negatively charged phospholipid or w hen beta 2-GPI is adsorbed on a polyoxygenated polystyrene plate. A ho mology based model of beta 2-GPI was constructed based on the NMR coor dinates of sushi domains of human factor H. The conformation was like a cylinder consisting of five domains, its IV and V domains being glue d by electrostatic interaction. We used phage-displayed random peptide libraries to search the epitopes of human aCL. Structures similar to consensus sequences selected by a biopanning method was found on domai n IV of beta 2-GPI.