Inclusion Criteria:  Confirmed primary refractory ITP Platelet counts <30×10^9/L or with bleeding symptoms Willing and able to sign written informed consent  Exclusion Criteria:  Secondary thrombocytopenia Received chemotherapy or anticoagulants or other drugs affecting the platelet counts within 6 months before the screening visit HIV infection or hepatitis B virus or hepatitis C virus infections Malignancy Severe medical condition (e.g., unstable angina, congestive heart failure, uncontrolled hypertension or cardiac arrhythmia) Nursing or pregnant patients Patients who are deemed unsuitable for the study by the investigator