LACK OF CROSS-REACTION BETWEEN ANTIBODIES TO BETA-2-GLYCOPROTEIN-I AND OXIDIZED LOW-DENSITY-LIPOPROTEIN IN PATIENTS WITH ANTIPHOSPHOLIPID SYNDROME

Previous studies have shown a cross-reaction between anticardiolipin a nd anti-oxidized low-density lipoprotein (LDL) antibodies in patients with the antiphospholipid syndrome (APS). The aim was to investigate t he existence of a cross-reaction between anti-beta 2-glycoprotein-I (b eta 2-GP-I) and anti-oxidized LDL antibodies in a group of APS patient s. Ninety-three patients with APS were included in the study 47 of the se patients were diagnosed as primary APS, while the rest (46 patients ) fulfilled criteria for the classification of systemic lupus erythema tosus (SLE). All patients were positive for the IgG isotype of anticar diolipin antibodies (aCL). Twelve (26%) SLE-associated APS and 14 (29. 7%) primary APS patients had raised concentrations of IgG antibodies t o oxidized LDL. There was no correlation between anti-beta 2-GP-I and anti-oxidized LDL antibodies. Inhibition experiments showed no cross-r eaction either between anti-beta 2-GP-I and anti-oxidized LDL antibodi es, or between anti-beta 2-GP-I and anti-native LDL antibodies. Our st udy suggests that the presence of both anti-beta 2-GP-I and anti-oxidi zed LDL antibodies in patients with APS is not due to the structural s imilarity and consequent cross-reaction, and that they are two differe nt populations of antibodies directed against different antigens.