Role of β2‐glycoprotein I in the pathogenesis of the antiphospholipid syndrome

Abstract Antiphospholipid syndrome (APS) is typically characterized by increased levels of three classes of antiphospholipid antibodies, namely lupus anticoagulant, anti‐β2‐glycoprotein I (anti‐β2GPI), and anticardiolipin antibodies. β2‐Glycoprotein (β2GPI) is a phospholipid‐binding protein composed of five domains (DI–V) and a major antigen in APS. β2GPI is expressed on the surfaces of several cell types, including endothelial cells, monocytes, trophoblast cells, and platelets. Its binding to the anti‐β2GPI antibody triggers downstream signaling events and ultimately exerts a variety of cellular effects. β2GPI modulates hemostasis and the complement system, as well as playing an important role in APS‐associated vascular injury. Therefore, studying β2GPI will help elucidate the pathogenesis of APS and improve the treatment of patients with this condition. This review will mainly focus on the structure and function of β2GPI, as well as its implication in the pathogenesis of APS.