What do we learn from immunomodulation in patients with immune thrombocytopenia?

Current therapeutic strategies for autoimmune diseases primarily rely on immunosuppression, but global immune suppression results in an increased risk for severe infection and malignancy. In contrast, immuomodulation is another therapeutic approach employing intrinsic or environmental regulators that exert modulatory effects by intervening multiple checkpoints of the immune system, leading to correction of dysregulated immune responses. We have learned that immunomodulation by intravenous immunoglobulin is highly efficacious and safe in patients with immune thrombocytopenia (ITP), an autoimmune disease mediated by IgG antiplatelet autoantibodies. Recently, another types of immunomodulatory treatment are also effective for ITP. These include eradication of Helicobacter pylori and thrombopoietic agents, such as thrombopoietin receptor agonists. These treatment modalities are shown to exert immunomodulatory action by suppressing multiple checkpoints of the pathogenic loop of ITP, although only certain subsets of the patients show robust responses. Understanding mechanisms underlying immunomodulation is highly useful in clarifying pathogenesis of immune-mediated diseases and developing novel therapeutic approaches.