Comprehensive flow cytometry phenotype in acute leukemia at diagnosis and at relapse

Multiparameter flow cytometry (MFC) plays a vital role in the detection of minimal residual disease (MRD) and diagnosis of relapse in acute leukemia. However, application of a limited panel of antibodies in MFC leads to high rates of false-negative and false-positive results. Thirteen patients with acute lymphoblastic leukemia (ALL) and 12 patients with acute myeloid leukemia (AML) were immuno-phenotyped by MFC at diagnosis and at relapse using a comprehensive panel of monoclonal antibodies (McAbs) to 27 antigens and CD45/SSC gating. In 23 of 25 patients (92.3%), changes in at least one of progenitor-associated, myeloid and lymphoid antigens between diagnosis and relapse were observed. Antigen changes were observed in 92 of 239 antigens (38.5%) expressed in 25 patients, in 49 of 117 antigens (41.9%) expressed in 13 ALL patients, and in 43 of 122 antigens (35.2%) expressed in 12 AML patients. Phenotypic changes were characterized by the expression of cross-lineage antigens. The intra-lineage change was observed in the majority of patients. However, myeloid lineage shift was identified by MFC in two patients with T-ALL. Multiple panels of three or more McAbs are likely to be required in the monitoring of MRD and diagnosis of relapse in acute leukemia by MFC.