Low dose IL-2 increase regulatory T cells and elevate platelets in a patient with immune thrombocytopenia.

Immune thrombocytopenia (ITP) is an autoimmune disorder in which its immune system destroys platelets and leads to haemorrhage symptom. Recent studies have found that regulatory T cells (Tregs) in peripheral blood, bone marrow, and spleen were reduced in ITP patients and recovered after effective ITP therapy. Low-dose Interleukin-2 (IL-2) has been reported recently to increase Tregs and used to treat autoimmune disease including graft-versus-host disease (GVHD) after organ transplantation and HCV-related autoimmune vasculitis. However, it is unknown whether IL-2 is able to treat ITP. We have used low-dose IL-2 (1.0 million IU/day) on 5 consecutive days per week for 4 weeks in a 36-year-old patient with ITP. The result has shown that low-dose IL-2 induces expansion of Tregs significantly and increase platelet count was gradually from 36 × 109 /L to maximum 85 × 109 /L. No side effects of IL-2 have been found. This result suggested that low-dose of IL-2 may have therapeutic potential for ITP.