Beta-2 glycoprotein 1 (beta-2 GP1, also called apolipoprotein H) is a 326-amino acid polypeptide synthesized by hepatocytes, endothelial cells and trophoblast cells.. The persistent presence of IgG and/or IgM beta 2 glycoprotein I (B2GPI) antibodies (greater than 99th percentile) is a laboratory criterion for the diagnosis of antiphospholipid syndrome (APS).. Clinical Information. Beta-2 glycoprotein 1 (beta-2 GP1, also called apolipoprotein H) is a 326-amino acid polypeptide synthesized by hepatocytes, endothelial cells, and trophoblast cells.. Apolipoprotein H (Apo-H), previously known as β 2-glycoprotein I and beta-2 glycoprotein I, is a 38 kDa multifunctional apolipoprotein that in humans is encoded by the APOH gene . Strongly positive results for beta-2 glycoprotein 1 (beta-2 GP1) antibodies (>40 U/mL for IgG and/or IgM) are diagnostic criterion for antiphospholipid syndrome (APS). Lesser levels of beta-2 GP1 antibodies and antibodies of the IgA isotype may occur in patients with clinical signs of APS, but the results are not considered diagnostic. Beta-2 GP1 antibodies must be detected on 2 or more . Useful For. Evaluation of patients with suspected antiphospholipid syndrome by identification of beta-2 glycoprotein 1 (beta-2 GP1) IgG and IgM antibodies.