Apolipoprotein H, also known as beta-2-glycoprotein I, is a component of circulating plasma lipoproteins. It has been implicated in a variety of physiologic pathways including lipoprotein metabolism, coagulation, hemostasis, and the production of antiphospholipid autoantibodies. APOH may be a required cofactor for anionic phospholipid binding by the antiphospholipid autoantibodies found in sera of many patients with lupus and primary antiphospholipid syndrome (APS). The anti-beta (2) glycoprotein I antibodies from APS patients, mediate inhibition of activated protein C which has anticoagulant properties. Because beta-2-GPI is the main autoantigen in patients with APS, the disruption of this pathway by autoantibodies may be an important mechanism for thrombosis in patients with APS.[provided by RefSeq, Dec 2019] see less Apolipoprotein H, also known as beta-2-glycoprotein I, is a component of circulating plasma lipoproteins. It has been implicated in a variety of physiologic pathways including lipoprotein metabolism, coagulation, hemostasis, and the production of antiphospholipid autoantibodies. APOH may be a required cofactor for anionic phospholipid binding by the antiphospholipid autoantibodies found in sera... see more