Measurement of antiphospholipid antibody by ELISA using purified beta 2-glycoprotein I in preeclampsia.

It has been reported that the binding of some antiphospholipid antibodies (APA) to phospholipids requires the presence of beta 2-glycoprotein I (beta 2-GPI). Using a new ELISA, in which well coated phospholipids were treated with a constant amount of purified beta 2-GPI, we tried to detect the presence of APA which binds to phospholipid/beta 2-GPI complex or to phospholipids such as cardiolipin (CA) and phosphatidylserine (PS) in preeclampsia, and to check for clinical abnormalities in antibody-positive cases. Serum samples were taken from 43 cases of preeclampsia, including 26 cases of the severe type, and 47 normal pregnant women. Positive rates of anticardiolipin antibody (ACA) by ELISA using CA/beta 2-GPI complex in mild, severe and total preeclampsia were 20.0, 17.4% and 18.4% respectively. No antibody-positive cases were found in normal pregnancies. ACA was detected much more frequently when cardiolipin/beta 2-GPI complex was used in ELISA compared with ELISA without beta 2-GPI. Positive rates of antiphosphatidylserine antibody (APSA) in mild, severe and total preeclampsia were 5.9%, 11.5% and 9.3% respectively. APSA was also detected much more frequently when the phosphatidylserine/beta 2-GPI complex was used in ELISA. The frequency of intrauterine growth retardation (IUGR) in the ACA-positive subjects was higher than that of ACA negatives. We suggest that the ACA and APSA which bind to phospholipid/beta 2-GPI complex are detectable in preeclampsia, and that these antiphospholipid antibodies are related to fetal growth.