Immunoregulatory abnormalities in children with thrombocytopenic purpura.

Twenty-eight children with idiopathic thrombocytopenia and 51 members of their immediate families were studied for immunologic function and expression of autoimmune phenomena and disease. Among patients with active ITP, 64% had defective immunoregulatory lymphocytes. The majority of patients (23/28) and family members had one or more immunologic abnormalities, including autoantibodies, other autoimmune disorders, and abnormalities in complement, immunoglobulins, or regulatory T lymphocytes. These data suggest that a genetic predisposition to autoimmunity is present in the majority of children with ITP.