Immunological evaluation of minimal residual disease (MRD) in acute myeloid leukaemia (AML)

Immunophenotypic analysis of leukaemic cells using multiparametric flow cytometry has proved to be an attractive approach for MRD investigation in acute lymphoblastic leukaemia (ALL); by contrast, information on acute myeloid leukaemia (AML) is still scanty. Here, we first review the methodological strategies for these studies. Triple or quadruple antigenic combinations, analysed by multiparametric flow cytometry, have shown that in 80% of AML patients it is possible to identify aberrant or uncommon phenotypic profiles on blast cells, thereby allowing their distinction from normal cells and their use as leukaemia-associated phenotypes (LAP). We also focus on technical aspects that are important in the definition of LAP. We then review pitfalls that could potentially affect results using this approach. Finally, we review available information concerning the clinical value of these studies. Although reported data in the literature are still scanty, several authors have shown that this technique could be used for the prognostic evaluation of AML patients, when immunophenotypic evaluation is applied after induction therapy.