Novel approaches to refractory immune thrombocytopenic purpura.

Chronic immune thrombocytopenic purpura (ITP) is an organ-specific autoimmune bleeding disorder in which autoantibodies are directed against the individual's own platelets, resulting in increased Fc-mediated platelet destruction by macrophages in the reticuloendothelial system. Although ITP is primarily mediated by IgG autoantibodies, the production of these autoantibodies is regulated by the influence of T lymphocytes and antigen-presenting cells (APC). There is evidence that enhanced T-helper cell/APC interactions in patients with ITP may play an integral role in IgG antiplatelet autoantibody production. New therapies may improve platelet production, decrease platelet antibody production, and decrease monocyte function and/or B-cell and T-cell activities. Understanding these cellular immune responses in ITP may lead to the development of more specific immunoregulatory therapies for the management of this disease.