Immunophenotyping of 222 children with acute leukemia by multi-color flow cytometry

Objective Acute leukemia (AL) is one of the most common malignant diseases in children. AL immunophenotypes are known to be benefit to the predictable prognoses and specific therapy. Recently, the accuracy of AL immunophenotyping was dramatically improved with the application of the flow cytometry, the new monoclonal antibodies, the improvement of the gating strategies and the multi-parameter analytic techniques. The aim of this study was to evaluate the value of multi-color flow cytometry in the immunophenotyping of acute leukemia in children. Methods Three- or four-color flow cytometry and CD 45/Side Scatter (SSC) gating were used to analyze the surface and cytoplasmic (Cy) antigen expressions in 222 successive cases of childhood acute leukemia. Results Cells from 222 cases of children with acute leukemia were analyzed. Based on the diagnostic criterion proposed by European Group for the Immunological Characterization of Leukemia (EGIL), four categories could be identified: the undifferentiated type accounted for 0.9%, acute myeloid leukemia (AML) 35.1%, acute lymphoblastic leukemia (ALL) 55.9%, and mixed lineage AL 8.1%. Of 124 patients with ALL, 94 patients (75.8%) were classified as B lineage and 30 patients (24.2%) T lineage ALL. Antigen aberrant expressions were found in AML (24.4%), B lineage ALL (36.2%) and T lineage ALL (30.0%). CD 7 was the most commonly expressed lymphoid antigen in AML (12.8%), followed by CD 19 (6.4%) and CD 2 (5.1%). CD 13 was the most commonly expressed myeloid antigen in ALL (18.5%), followed by CD 15 (11.3%), CD 11b (6.5%) and CD 33 (4.3%). CD 117 and CD 56 presented in 73.3% and 38.0% cases of AML, respectively, but were generally absent on blast cells of ALL. CyCD 22, CyCD 3 and CyMPO were specifically expressed in B lineage, T lineage and myeloid lineage leukemia, respectively, and the first two could be more sensitively detected than they were on cell membrane surface. Conclusions Multi-color flow cytometry is a reliable technique in the diagnosis, differential diagnosis and classification of acute leukemia in children.