Objective        To study the expression of HA117 protein in bone marrow mononuclear cells (BMMNC) of children with acute leukemia (AL) and its clinical significance.       Methods        Sixty-seven AL children were divided into initial diagnosis group

complete remission group and non-remission group. Ten children with immune thrombocytopenia (ITP) served as a control group. Expression of HA117

protein and P-glycoprotein (P-gp) was detected with immunohistochemical methods.       Results       The HA117 protein was positively expressed in complete remission group

initial diagnosis group

non-remission group

and negatively expressed in control group. The first complete remission (CR

1

) rate was significantly lower in initial diagnosis group and complete remission group or non-remission group than in control group (16.67% vs 94.74% and 87.50%

P0.01 or P0.05）. No correlation was observed between the expressions of HA117 protein and P-gp in a same AL child (Kappa=0.195

P0.05). The CR rate of HA117

+

protein and P-gp

+

was significantly lower than that of HA117

+

/P-gp

-

and HA117

-

/P-gp

+

(30.00% vs 83.33% and 94.44%

P0.05）.       Conclusion       Over-expression of HA117 protein

which is closely correlated with clinical resistance to chemotherapy

is an unfavorable factor for the prognosis of AL children and its drug resistance may be mediated by the independent non P-gp. Over-expression of both HA117 protein and P-gp indicates a poor prognosis of AL children.