This study aimed to evaluate the efficacy of interferon α after prophylactic donor lymphocyte infusion (DLI) among high-risk acute leukemia patients undergone unmanipulated blood and marrow transplantation. Hematopoietic stem cell transplantation (HSCT) is an effective treatment option for high-risk acute leukemia (AL). However, post-transplant relapse can occur in some patients, and the prognosis of these patients is usually very poor.Prophylactic DLI can decrease the risk of relapse of high-risk AL patients. Interferon α-2b exerts a relatively strong immunomodulatory effect. It can kill AL cells by regulating T-cell and/or natural killer cell functions.Consequently, interferon α-2b may have potential value for high-risk AL patients after transplantation. The study hypothesis: Using interferon α-2b after prophylactic DLI following hematopoietic stem cell transplantation in patients with high-risk AL can further reduce relapse rate and improve leukemia-free survival.

High risk acute leukemia patients (except t(9;22)(q34; q11) cytogenetic abnormalities.) received interferon α-2b after prophylactic DLI at day 30-60 after unmanipulated blood and marrow transplantation. The end points were safety, leukemia-free survival, and immunologic response. Following time is 12 months.

Inclusion Criteria:

• Patients who had high-risk acute leukemia after hematopoietic stem cell transplantation

Exclusion Criteria:

• Patients with t(9;22)(q34; q11) cytogenetic abnormalities;active graft-versus-host disease; active infection; organ failure, or relapse