[Immunophenotypic characteristics of children with acute lymphoblastic leukemia carrying TEL-AML1 fusion gene]

To investigate the immunological and other clinical characteristics in TEL/AML1+ childhood B-acute lymphoblastic leukemia (B-ALL), immunophenotyping was performed with three-color flow cytometry, and the expression of TEL-AML1 fusion gene was detected with nested RT-PCR. Diagnosis was made according to FAB and MIC criteria. The results showed that (1) among 119 children with B-ALL, 22 (18.5%) were TEL-AML1 positive and classified as L2 morphological subtype. In TEL-AML1+ group, positive rate and score of PAS, which were 65% and 121 respectively, were all higher than that of TEL-AML1- group (P < 0.05); (2) compared with TEL-AML1- group, no significant difference was found in age, gender, white cell count and blasts count in peripheral blood of TEL-AML1+; (3) in TEL-AML1+ group, 21 out of 22 (95.5%) were common ALL, as compared with TEL-AML1- group, the positive rate of CD13 was higher (59.1%, 13/22) and the positive rate of CD20 was lower (22.7%, 5/22) than that in TEL-AML1- group, respectively (P < 0.05), and the mean fluorescence index of CD10 and HLA-DR significantly increased to 92.80 and 53.61, respectively (P < 0.05). It is concluded that TEL-AML1 rearrangement is a frequent molecular abnormality in childhood ALL. Leukemic blasts with this anomaly have special immunophenotypic characteristics. These characteristics may be useful in detection of minimal residual leukemia.