Immunophenotypic characterization of pediatric acute myeloid leukemia with inv(16)(p13.1q22)/t(16;16)(p13.1;q22)/CBFb-MYH11

Abstract

The aim of this study was to describe the immunophenotype of leukemic cells in acute myeloid leukemia (AML) with inv(16) (p13.1q22)/CBFb-MYH11 and t(16;16)(p13.1;q22)/CBFb-MYH11 in children. This study is supported by the Independent Ethics Committee and approved by the Academic Council of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology. We investigated bone marrow samples from 36 pediatric patients with initially diagnosed AML with inv(16)(p13.1q22)/t(16;16)(p13.1;q22)/CBFb-MYH11. Immunophenotypic profile of leukemic cells was very heterogeneous: cells expressed antigens of early stages of differentiation (CD34, CD117, CD123) as well as markers of mature monocytes (CD11c, CD14, CD64) and neutrophils (CD65, CD15). Moreover, in 55.6% of cases lymphoid coexpressions were noticed (CD2 – the most frequent one). Furthermore, in 83.3% of cases we detected the separation of leukemic cells population into two parts: more “immature” – myeloblastic, which expressed early markers of differentiation (CD34, CD117), and more “mature” part, expressing monocytic antigens (CD11b, CD14, CD33). There was no clear separation between these parts of population. Despite the immunophenotypic similarity between monocytic part of leukemic population and normal monocytes, in 87.5% of studied cases there were same lymphoid coexpressions on these cells as on leukemic myeloblasts. Moreover, we showed that levels of CBFb-MYH11 expression in leukemic monocytes and myeloblasts were comparable. Presence of these characteristics in monocytes allows to consider them as part of leukemic cells population and take into consideration during the total immunophenotype reporting.