Anticardiolipin Antibodies in Juvenile Rheumatoid Arthritis and Systemic Lupus Erythematosus

Background: Antiphospholipid antibody syndrome (APS) can either occur as a primary syndrome or associated with other autoimmune diseases such as systemic lupus erythematosus (SLE). Anticardiolipin antibody (aCL) of IgG and/or IgM isotype in blood, measured by a standardized ELISA is the most acceptable laboratory criteria. APS IgG isotype, particularly IgG2 subclass is more strongly associated with thrombosis. Objectives: This study was done to determine the prevalence of IgG aCL and its subclasses in relation to APS symptoms, in a group of juvenile rheumatoid arthritis (JRA) and juvenile systemic lupus erythematosus (SLE) patients.   Methods: In this prospective study, 28 JRA and 16 SLE patients, aged 3-18 years, were enrolled. IgG aCL was assayed by standard aCL ELISA. IgG subclasses were also assayed by ELISA on sera with medium to high titers of aCL. ACL assay was performed on at least two occasions for each patient, over 3-6 months period of follow up.   Results: 29% (8/28) of JRA patients and 44% (7/16) of SLE patients had aCL. Six of SLE patients displayed APS related manifestations: hemolytic anemia, thrombocytopenia, arterial occlusion, valvular heart disease, livedo reticularis and pulmonary hypertension, but none of them had persistant medium or high titer of aCL. The lack of association of high titer of aCL with APS related symptoms was observed in two patients. The IgG subclasses were primarily IgG1 and IgG3.   Conclusion: The prevalence of IgG aCL in this group of pediatric SLE and JRA is not uncommon but it’s relation to clinical manifestations is not clear. IgG1 and IgG3 subclasses were not associated with thrombosis, which is in agreement with previous studies.