Therapeutic potential of low-dose IL-2 in immune thrombocytopenia: An analysis of 3 cases.

Immune thrombocytopenia (ITP) is an acquired immune-mediated disorder with regulatory T cells (Tregs) reduction. Recent studies have shown that low-dose interleukin-2 can preferentially induce Treg expansion in vivo, and therefore offers a therapeutic strategy against immune thrombocytopenia. We have demonstrated in a previous study that Tregs and platelet counts significantly improve in an adult with ITP following low-dose IL-2 treatment. Here we report the efficacy of low-dose IL-2 in another three adults with immune thrombocytopenia who failed the first-line treatment. All patients received a dose of 1.0 million IU IL-2/day for 5 consecutive days per week as a cycle for 2 or 4 weeks. In addition to IL-2, vincristine (2 mg IV weekly × 3 weeks) was added to one patient as a combination therapy. No specific treatment was added in the other two patients. Two cases exhibited significantly increased platelet counts with improved levels of Tregs, while no changes were observed for the remaining patient. In summary, administration of daily subcutaneous low-dose IL-2 was safe, and it may be a new therapeutic option for treatment of ITP, especially refractory ITP. © 2017 International Clinical Cytometry Society.