[Clinical subsets and phospholipid-dependent anti-beta 2-glycoprotein I antibodies in antiphospholipid syndrome]

Clinical significance of IgG phospholipid-dependent anti-beta 2-glycoprotein I (beta 2-GPI) antibodies in patients with antiphospholipid syndrome (APS) was studied. The subjects consisted of 14 patients with primary APS (PAPS) and 32 with secondary APS based on SLE. IgG phospholipid-dependent anti-beta 2-GPI antibodies were examined by ELISA. Incidences of malar rash, arthritis, renal disorder, leucopenia, immunological disorder, and hypocomplementemia were significantly less frequent in patients with PAPS than in those with secondary APS based on SLE. However, sustained positive reactions of IgG anticardiolipin antibodies were found in 86% of patients with PAPS. Frequency of IgG phospholipid-dependent anti-beta 2-GPI antibodies was significantly higher in patients with PAPS (100%) than in those with secondary APS (34%). Moreover, titer of IgG phospholipid-dependent anti-beta 2-GPI antibodies was significantly higher in patients with PAPS than in those with secondary APS. These data indicated that IgG phospholipid-dependent anti-beta 2-GPI antibodies are useful for identifying a subset in patients with APS as well as for studying the mechanism of thrombotic events in these patients.