BETA-2-GLYCOPROTEIN-I AND ANTI-BETA-2-GLYCOPROTEIN-I ANTIBODIES - WHERE ARE WE NOW

beta 2-Glycoprotein I (beta 2-GPI), a plasma protein with in vitro ant icoagulant properties, has been recognized to have an important role i n the antiphospholipid syndrome (APS) as a cofactor and an (co)antigen in ELISA assays. Although beta 2-GPI levels were found to be increase d in some patients with APS, the clinical value of measuring beta 2-GP I levels in APS is not known. Several reports have suggested that anti -beta 2-GPI antibodies may be a marker for the APS and might be more s pecific for the vascular complications of the APS than anticardiolipin antibodies. There have been major discoveries about phospholipid (PL) and antibody binding sites on beta 2-GPI, although more studies are n eeded. Reports of changes in cell membrane PL composition or exposure of other anionic molecules by apoptosis, cell activation and oxidative injury suggest mechanisms to explain beta 2-GPI binding and the gener ation of cryptic epitopes for aPL/anti-beta 2-GPI antibodies.