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 acute B lymphoblastic leukemia

Abstract

Introduction. 60-80% of patients with acute B lymphoblastic leukemia show genetic abnormalities that 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 to immunophenotype and proliferative rate compared to normal B cell precursors.

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

Results. DNA quantification showed that 21% of the cases were hyperdiploid high index and 47.47% hyperdiploid low index. The presence of hyperdiploidy was associated with increased tumor proliferation and aberrant immunophenotypes including abnormal expression of CD10, TdT, CD38 and CD45 and increased size of the lymphoblasts. The presence of t(9;22) and t(12;21) discriminates normal cells of the 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 in conjunction with abnormalities in proliferative rate was significantly associated with DNA hyperdiploidy and clearly distinguished blasts with t(9;22) and t(12;21) of normal B cell precursors. The identification of these parameters is useful as a tool for classification and monitoring of these patients.

doi: http://dx.doi.org/10.7705/biomedica.v33i3.1441