The purpose of this study is to determine whether All-trans retinoic acid (ATRA) are effective in the treatment of refractory idiopathic thrombocytopenic purpura (RITP).

Idiopathic thrombocytopenic purpura(ITP), an acquired immune disease is characterized by impaired generation of autoantibody-specific platelet. At least 30% adult patients turn into refractory ITP. The pathogenesis of ITP remains to be elucidated. Now ,CD4+ helper cells have been classified as belong to T-helper 1(TH1), T-helper 2(TH2), T-helper17and Regulory T cell(Tregs). All-trans retinoic acid(ATRA) mainly applied in skin disease and acute promyelocytic leukemia. Recently, ATRA is also a immunomodulator which can induce differentiation, proliferation, apoptosis of cells, and immunomudulatory. In the international, the investigators first treat RITP with ATRA. To investigate the therapeutic effects of ATRA on RITP, and using new index in the cells, cytokines and molecular biology of three in-depth study of its mechanism.

Inclusion Criteria:

• Clinical diagnosis of refratory idiopathic thrombocytopenic purpura
• Hormone and immune suppression, splenectomy is invalid

Exclusion Criteria:

• Other autoimmune diseases

35 patients of RITP who do not response to prednisone,immunosuppressive agents and/or splenectomy were observed in our study .