OBJECTIVETo investigate the biological characteristics of childhood T-lineage acute lymphoblastic leukemia (T-ALL) and their clinical significance.

METHODSImmunophenotyping was performed by three-color flow cytometry analysis using CD45 /SSC gating in 23 children with newly diagnosed T-ALL. Meanwhile cytogenetic analysis was performed.

RESULTSCD3(+) expression of T-lineage antigens was apparently higher than CD7(+) and CD5(+) expression. CD19(+) expression of B-lineage antigens was apparently higher than CD22(+), CD10(+) and CD20(+) expression. Myeloid antigen was expressed in 4 cases (17%). CD34(+) and HLA-DR(+) were observed in 4 cases (17%) and 5 cases (22%), respectively. cCD3(+) and cCD79(+) were expressed in 23 cases (100%) and 22 cases (96%), respectively. The chromosome detection in 8 cases with T-ALL showed hyperdiploid or Ph(+) chromosome (one case each). The fusion gene detection in 5 cases showed MLL rearrangements in two cases and positive SIL/TAL1 fusion gene in one case. CD3 expression was related with the complete remission rate.

CONCLUSIONSImmunophenotyping is an important tool for diagnosis of T-ALL. However, the immunophenotype of T-ALL is heterogeneous. So, immunophenotyping along with cytogenetic and molecular genetic analysis is needed in the treatment and prognosis evaluation of T-ALL.