【Objective】 The objective of this study was to investigate the myeloid antigen expression features of adult acute lymphoblastic leukemia (ALL) patients and its correlation with clinical characteristics and prognostic significance

then compare the effects of various induction regimen for MyAg+ALL patients.【Methods】 A total of 159 newly diagnosed ALL patients with a median age of 26 years were enrolled in this study from January 2006 to May 2011. These patients were divided into myeloid antigen-positive group (MyAg+ALL) and myeloid antigen-negative group (MyAg-ALL) based on the flow cytometric (FCM) analysis in bone marrow. Myeloid antigen expression and its correlation with the clinical features

short-term efficacy and 5-year overall survival were assessed in the two groups.【Results】 Myeloid antigen expression was detected in 45.9% out of 159 cases and CD13

CD33 were the most commonly expressed MyAg (31.4% and 21.4%

respectively). The clinical and biological characteristics of ALL patients showed that higher percentage of incoincidence of classification between morphology and immunology and higher CD34 positivity were found to be correlated with MyAg+ALL. Significant difference was observed in the expression of MyAg between the groups of patients with T-ALL (66.7%) and B-ALL (42.8%). The complete remission (CR) rate was not significant in MyAg+ALL patients after receiving VDLP

VDCP or MA as induction therapy. MyAg expression was associated with lower CR rate but not with 5-year overall survival rate.【Conclusion】 Induction treatment combining mitoxantrone and cytarabine would not improve the CR rate of MyAg+ALL. MyAg expression was not correlated with prognosis in adult ALL.