Elevated levels of beta 2 glycoprotein-I (beta 2 GPI) in antiphospholipid antibody syndrome are due to increased amounts of beta 2 GPI in association with other plasma constituents

Blood Coagul Fibrinolysis. 1995 Jul;6(5):411-6. doi: 10.1097/00001721-199507000-00006.


beta 2 glycoprotein-I (beta 2 GPI) is a 50 kDa plasma protein which associates with a number of anionic plasma constituents and has been identified as a cofactor for the binding of some antiphospholipid antibodies (aPAs). beta 2 GPI antigen levels are increased in some patients with aPAs. In order to examine the distribution of beta 2 GPI in these patients, we developed a method for measurement of free beta 2 GPI. Forty-three patients with SLE, of whom 18 had laboratory evidence of aPAs, and 22 normal healthy subjects were studied. Plasma was filtered by centrifugation at 650 x g through a 100 kDa filter in order to allow separation of free and complexed beta 2 GPI, and beta 2 GPI levels were measured in the starting plasma and filtrate by a standardized ELISA. Total beta 2 GPI levels of the SLE aPA positive patients (253.3 mg/l) were significantly increased compared with the SLE aPA negative patients and normal controls (188.0, P < 0.001 and 194.9 mg/l, P < 0.01, respectively), but there were no significant differences between free beta 2 GPI levels of these groups (20.8, 24.0 and 20.5 mg/l, respectively). These results suggest that levels of complexed beta 2 GPI are increased in patients with aPAs, perhaps as a result of immune complex formation, or altered binding to other plasma constituents.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antigen-Antibody Complex / blood
  • Antiphospholipid Syndrome / blood*
  • Antiphospholipid Syndrome / immunology
  • Apolipoproteins / blood
  • Blood Proteins / metabolism*
  • Female
  • Glycoproteins / blood*
  • Humans
  • Immunoelectrophoresis, Two-Dimensional
  • Lupus Erythematosus, Systemic / blood
  • Lupus Erythematosus, Systemic / immunology
  • Male
  • Middle Aged
  • Phospholipids / blood
  • beta 2-Glycoprotein I


  • Antigen-Antibody Complex
  • Apolipoproteins
  • Blood Proteins
  • Glycoproteins
  • Phospholipids
  • beta 2-Glycoprotein I