Usefulness of Anti-beta2-Glycoprotein I Antibody Test for the Diagnosis of Antiphospholipid Syndrome

Lee, Hye Rim; Kim, Think You; Kim, Sun E

Abstract

BACKGROUND: The conventional anticardiolipin antibody (aCL)-ELISA test that has been widely used to diagnose antiphospholipid syndrome (APS) has drawbacks in that false-positive reactions can occur. There have been considerable controversy as to the exact nature of the epitopes to which antiphosholipid antibodies (a PL) are directed. Almost all investigators now agree that the actual antigen to which aPL derived from patient with APS is directed, is beta2-glycoprotein I (beta2GPI). Therefore, we thought that anti-beta2GPI antibodies (abeta2GPI) might be a more specific marker for APS, and attempted to evaluate the usefulness of abeta2GPI test.
METHODS
ELISA tests for a CL-IgG and abeta2GPI-IgG were performed simultaneously using the sera from 70 patients with clinically suspected APS and 10 healthy volunteers. The results of abeta2GPI were compared with those of aCL and evaluated clinically by reviewing the medical records.
RESULTS
The correlation coefficient between the two was 0.54 (p<0.005). Twelve of 70 patients were abeta2GPI-positive and they were also positive for aCL (mean 45GPL). Forty of 58 abeta2GPI- negative patients were aCL-positive, and many of them were diagnosed to have APS clinically. There was no case showing aCL-negative but abeta2GPI-positive result.
CONCLUSIONS
According to our results, abeta2GPI test seems specific but too insensitive to differentiate APS by itself, so it has no additional diagnostic value superior to aCL test. We believe that a study which includes more cases and various test methods will be needed for the precise assessment of abeta2GPI test.