Anticardiolipin antibodies in pediatric systemic lupus erythematosus.

To investigate the prevalence and the clinical significance of anticardiolipin antibodies (ACLs) in a group of children with systemic lupus erythematosus (SLE).Cross-sectional and longitudinal study.Pediatric Clinic, University of Pavia, Italy.Thirty children (aged 4.9 to 16.5 years) with SLE.Twenty-six (87\%) of the 30 patients were initially positive for either IgG or IgM ACLs; 24 (80\%) of 30 had IgG ACLs, and 15 (50\%) of 30 had IgM ACLs. The cross-sectional analysis showed a trend for IgG ACLs to be positively associated with autoimmune cytopenia and negatively associated with renal disease. The levels of ACLs, particularly of the IgG isotype, tended to correlate with SLE activity as expressed by the complement fraction C3, the erythrocyte sedimentation rate, or the SLE Activity Measure, but not by the SLE Disease Activity Index or the anti-DNA antibodies. Serial determinations of ACL levels in 20 patients revealed frequent fluctuations. High levels of IgG ACLs (> 50 arbitrary units) were observed in nine patients; all nine had active disease and eight had one or more clinical features that have been previously associated with antiphospholipid antibodies: neuropsychiatric manifestations in six patients, autoimmune cytopenia in two patients, and avascular necrosis of bone in one patient. Only one patient experienced an overt episode of vascular thrombosis; IgG ACLs were positive at a medium level 6 months before the thrombotic event, but their level was unchanged when the thrombosis was discovered; the lupus anticoagulant test was positive at time of the thrombosis.Our results show that in pediatric SLE, ACLs are frequently found, high levels of IgG ACLs are often associated with central nervous system involvement, and ACLs have a low predictive value in the development of vascular thrombosis.