Antiphosphatidylserine antibodies in patients with autoimmune diseases andHIV-infected patients: Effects of Tween 20 and relationship with antibodies to beta 2-glycoprotein I

Antiphospholipid antibodies (aPL) react with negatively charged phospholipi ds, which may often be complexed with a protein cofactor such as beta 2 gly coprotein (beta 2GPI) and prothrombin. Cofactor requirements may be assesse d by measuring antibodies to beta 2GPI or by adding Tween 20 to some reagen ts in the assays for aPL (anticardiolipin and antiphosphatidylserine). We h ave measured anticardiolipin antibodies (aCL), antiphosphatidylserine antib odies (aPS), and anti beta 2 glycoprotein antibodies (a beta 2GPI) in the s erum of 10 normal subjects, 20 patients with systemic autoimmune diseases ( SAD) diagnosed as having systemic lupus erythematosus (SLE) or antiphosphol ipid syndrome (APS), and 12 patients with HIV infection. Adding Tween 20 to aPS, the assay couldn't differentiate protein cofactor dependent from inde pendent antibodies, but this can be done by measuring a beta 2GPI (P = 0.00 08). There was a significant correlation between aCL and a beta 2GPI in the control group and in the patients with SAD, but not in the HIV-positive (H IV+) patients. After excluding the HIV+ patients, the best Spearman correla tion was obtained between a beta 2GPI and aCL (0.64, P < 0.0005). In 3 out of 7 patients with positive a beta 2GPI and in 5 out of 6 patients with mod erate or high positive aCL of the group of SAD, there was a history of veno us thrombosis. The presence of moderate or high Values of aCL either alone or together with a beta 2GPI was significantly associated with a history of venous thrombosis (P < 0.05). Moderate or high aCL concentrations and thei r association with a beta 2GPI seems to be useful for the assessment of the risk of venous thrombosis in unselected patients with SLE or APS. J. Clin. Lab. Anal. 13:59-64, 1999. (C) 1999 Wiley-Liss, Inc.