OBJECTIVEThe prognostic significance of immunophenotyping in acute myeloid leukemia (AML) has been controversial. This study investigated the relationship of immunophenotypes with French-American-British (FAB) subtypes and chromosomal abnormalities and assessed the prognostic value of immunophenotyping in children with AML.

METHODSFrom January 1998 to May 2003, 75 children with newly diagnosed AML were enrolled on protocol AML-XH-99. Immunophenotypes were measured with the flow cytometry. According to the McAbs used, the patients were classified into five groups: panmyeloid antigens (CD13, CD33, and MPO), myeloid-lineage associated antigens (CD14, CD15), lineage-specific antigens (CD41, GlyA), progenitor-associated antigens (CD34, HLA-DR) and lymphoid-associated antigens (CD19, CD7). The probability of event-free survival (EFS) was estimated by Kaplan-Meier analysis. The distributions of EFS were compared using the log-rank test. Chi-square analysis or Fisher exact test was used to compare the differences in the distribution of biologic presenting features. A Cox proportional hazards model was used to identify independent prognostic factors.

RESULTSAt least one of panmyeloid antigens CD13, CD33 and MPO was expressed in 72 patents (97.3%). Two or more panmyeloid antigens were expressed in 45 patients (60.8%). The proportion of children with AML expressing one or more of the lymphoid-associated antigens was 24.3%. Lymphoid-associated antigen CD19 was expressed by blast cells in most of FAB M2 patients. The patients with acute promyelocytic leukemia were characterized by the absence of HLA-DR and lymphoid-associated antigens CD19 and CD7. Monovariate analysis showed immunophenotypes were not related to the complete remission rate after the first induction course and the 5-year-EFS. Multivariate analysis suggested immunophenotyping had no independent prognostic value in AML.

CONCLUSIONSImmunophenotyping can not be used independently in the evaluation of risk classification in children with AML. However, it is useful in the reorganization of special types of AML.