Immunologic Abnormalities of Juvenile Arthritis

Many immunologic abnormalities have been found in children with all forms of chronic arthritis, but few are clinically useful or well understood. However, in children with arthritis it is important to distinguish among those with rheumatoid factor, antinuclear antibodies, or hypogammaglobulinemia. Rheumatoid factor is specific for adult-type rheumatoid arthritis; the presence of antinuclear antibodies increases the likelihood that the child may develop uveitis; and hypogammaglobulinemia may be associated with complicating infections. Other unusual antibodies, autoantibodies, antigen-antibody complexes, and complement activation products are found in children with arthritis, but none of these define a diagnostic or consistent group of diseases. Similarly, changes in the numbers of immunologically active cells and regulating mechanisms occur but not in specific patterns. As yet, none of the known immunologic abnormalities explain the pathogenesis of these diseases and only a few appear disease specific.