Background: There are few reports on the relationship of anti-β2-glycoprotein-I antibodies and anti-cardiolipin antibodies in children with systemic lupus erythematosus (SLE). This study was undertaken to compare the serum levels of anti-β2-glycoprotein I (β2-GPI) antibodies with those of anticardiolipin (aCL) antibodies in SLE patients with secondary anti-phospholipid syndrome (SAPS) and without SAPS (WSAPS).

Methods: Forty-two SLE patients with SAPS and 68 without SAPS were studied. Serum aCL antibodies and anti-β2-glycoprotein I antibodies were measured by ELISA.

Results: The serum level of anti-β2-GPI antibodies in 57.1% (24/42) of the patients in the SAPS-SLE group was higher than that in the control group, whereas it was only 1.5% (1/68) in the WSAPS-SLE group (P<0.01). The serum level of aCL antibodies was higher in 6.68% (28/42) of the patients in the SAPS-SLE group and in 42% (29/68) in the WSAPS-SLE group (P<0.01).

Conclusions: Anti-β2-glycoprotein I (β2-GPI) antibodies are not only strongly associated with SAPS in children with SLE but also highly specific in predicting SAPS-SLE in comparison with aCL antibodies.

Key words: anti-β2-glycoprotein I; platelet; anticardiolipin antibodies; thrombopeny; hemolysis; children; SLE