Incidence, Sensitivity, and Specificity of Leukemia-Associated Phenotypes in Acute Myeloid Leukemia Using Specific Five-Color Multiparameter Flow Cytometry

We assessed the usefulness of 5-color multiparameter flow cytometry to detect leukemia-associated phenotypes (LAPs) in the bone marrow of patients with newly diagnosed acute myeloid leukemia (AML) and determined its usefulness for detection of minimal residual disease (MRD). Overall, 94% of patients (51/54) with AML had LAPs at diagnosis. The frequency of leukemic bone marrow/median frequency of LAPs in normal or regenerating bone marrow samples using maximum log difference statistics revealed that CD2, CD56, CD11b, CD7, and CD19 expression on AML blasts represented the most sensitive and reliable markers for detection of MRD. Serial dilutional experiments showed that the sensitivity level of immunophenotyping was between 10-4 and 10-5 and that the approach was highly reproducible. Immunophenotypic analysis using a CD45 gating strategy, 5-color staining, and an extensive panel of monoclonal antibodies allowed the identification of LAPs in 94% of AML cases, and these immunophenotypes can be used for MRD monitoring with a sensitivity limit of 10-4 to 10-5.