DETECTION OF ANTIPHOSPHOLIPID ANTIBODIES IN CHILDREN WITH IMMUNE THROMBOCYTOPENIC PURPURA

Purpose: Antiphospholipid antibodies (aPLs) are autoantibodies that ma y occur in patients with autoimmune disorders and recurrent vascular t hrombotic disease. Concurrent thrombocytopenia is frequently observed in these conditions. We prospectively studied a cohort of children wit h immune thrombocytopenic purpura (ITP), a disorder with a suspected a utoimmune etiology, for the presence of aPLs. Patients and Methods: Se rum obtained at diagnosis from 35 children with ITP was analyzed for t he presence of antibodies to six phospholipid moieties using an enzyme -linked immunosorbent assay. Assessment for the presence of fluorescen t antinuclear antibody (FANA) and anti-double-stranded DNA was also pe rformed. Results of the patient's clinical course arid aPL data were c orrelated. Results: Thirteen of 35 (37%) patients had aPLs detected in their serum. Nine of these had IgG antibodies alone, 3 had IgM alone, and 1 had both IgG and IgM aPLs. Eight patients had antibodies direct ed at more than one phospholipid moiety. Antiphosphatidylinositol anti body was the most frequently detected aPL. Patients who eventually dev eloped chronic ITP had a higher prevalence of aPLs, but there was no c orrelation between the presence of aPLs and the patient's response to oral corticosteroids or the presence of an antecedent viral illness. C onclusions: The incidence of aPLs in our cohort of patients with ITP i s between that reported for juvenile rheumatoid arthritis and systemic lupus erythematosus, two disorders with a known autoimmune basis. We conclude that the presence of antibodies to multiple phospholipids in childhood ITP may provide insight into the pathophysiological interact ion of these antibodies with platelet membrane components in other dis eases characterized by thrombocytopenia Further prospective studies ma y permit elucidation of a subgroup of patients who are more likely to develop chronic ITP or autoimmune disease.