Juvenile dermatomyositis: immunopathogenesis, role of myositis-specific autoantibodies, and review of rituximab use.

Juvenile dermatomyositis (JDM) is an autoimmune disease of the skin and muscle that affects children. The etiology is poorly understood, but genetic susceptibility, environmental triggers, and abnormal immune responses are each thought to play a part. T cells have traditionally been implicated in the immunopathogenesis of JDM, but dendritic cells, B cells, and microchimerism are increasingly associated. Additionally, myositis-specific autoantibodies (MSA) can be present in the sera of affected patients and may correlate with distinct clinical phenotypes. Given the role of humoral immunity and MSA, there has been recent interest in the use of rituximab to treat JDM. Early results are mixed, but it is hoped that a prospective clinical trial will shed light on the issue in the near future.