[Correlation of the t(9;22), t(12;21), and DNA hyperdiploid content with immunophenotype and proliferative rate of leukemic B-cells of pediatric patients with B-cell acute lymphoblastic leukemia]

Abstract

Introduction: Between 60 and 80% of patients with B-cell acute lymphoblastic leukemia show genetic abnormalities which influence the prognosis of the disease and the biology of the tumor.

Objective: To analyze different genetic abnormalities in acute B lymphoblastic leukemia in children, its relationship with the immunophenotype and the proliferative rate compared with normal B cell precursors.

Materials and methods: We assessed immunophenotype, DNA content and proliferative rate in 44 samples by flow cytometry, and translocations t(9;22), t(12;21), t(4;11), and t(1;19) by RT-PCR. Using a hierarchical cluster analysis, we identified some immunophenotypic patterns associated to genetic abnormalities when compared with normal B cell precursors.

Results: DNA quantification showed that 21% of the cases had high hyperdiploidy and 47.7% has low hyperdiploidy. The presence of hyperdiploidy was associated with increased tumor proliferation and aberrant immunophenotypes, including abnormal expression of CD10, TdT, CD38, and CD45 and an increased size of the lymphoblasts. The presence of t(9;22) and t(12;21) discriminates normal cells from tumor cells with aberrant immunophenotype in the expression of CD19, CD22, CD13, CD33, CD38, CD34, and CD45.

Conclusions: The aberrant immunophenotype profile detected in neoplastic cells along with abnormalities in the proliferative rate were significantly associated with DNA hyperdiploidy and clearly distinguished lymphoblasts with t(9;22) and t(12;21) from normal B cell precursors. The identification of these parameters is useful as a tool for classification and monitoring of these patients.