Anti-cardiolipin and anti-β2-glycoprotein I (β2GP-I) antibody assays as screening for anti-phospholipid syndrome

Background: Antiphospholipid antibodies are a family of autoantibodies that exhibit a broad range of target specificities and affinities, all recognizing various combinations of phospholipids, phospholipid binding proteins or both. Objective: To evaluate the frequency of an4ticardiolipin (aCL) or anti-beta-2 glycoprotein I (anti -βGPI) antibodies in a cohort of patients with primary (PAPS) and secondary (SAPS) antiphospholipid syndrome and other rheumatic and infectious conditions. Methods: Sera were drawn from 226 patients with PAPS (n = 66), SAPS (n = 60), rheumatoid arthritis (RA) (n = 30), scleroderma (SSc) (n = 30) or syphilis (n = 30). IgG, IgM, IgA aCL and anti-β2GPI antibodies were determined for all patients. We employed Varelisa diagnostic kits (Pharmacia Diagnostics GmbH & Co.KG, Germany). Results: In APS patients: aCL and anti-βGP1 antibodies were detected in 81.8% and 70% in PAPS and SAPS patients, respectively. In PAPS, aCL were detected in 71.2%, and anti-β2GP1 in 50% of patients. In SAPS, aCL were detected in 63.3%, and anti-β2GP1 in 53.3% of patients. In syphilis, aCL and anti-β2GP1 antibodies were detected in 46.7% of patients in low levels: aCL in 36.7% and anti-β2GP1 in 20% of patients. aCL antibodies were detected in 10%, 13.3%, and 0% of RA patients, SSc patients, and healthy persons, respectively. Anti-β2GP1 antibodies were not detected in RA patients, SSc patients, and healthy persons. Conclusions: aCL and anti-β2GP1 antibodies are more frequently found in sera of APS patients, and can be found in low levels in syphilis. Anti-β2GPI assay found to be more specific than aCL in antiphospholipid antibodies determination.