ABSTRACT
Leukemia is a group of heterogeneous blood disorders that involve clonal proliferation and developmental arrest of mature or immature blood cells. The leukemic cells can interfere with the production of normal blood cells and cause a variety of complications. Different diagnostic methods have evolved over the past century for the diagnosis of leukemia and the detection of measurable residual disease (MRD) and to assess the response to treatment. MRD is the subset of cells that persist in the bone marrow after treatment. Together, MRD and leukemia stem cell (LSC) persistence are believed to serve as the strongest risk factors for leukemia relapse. Flow cytometry, next-generation sequencing, and polymerase chain reaction are the most commonly used methods to identify these LSCs. Flow cytometry offers a unique ability to simultaneously assess and correlate multiple phenotypic properties at the single-cell level in a timely and efficient manner. Application of this technique to the detection of residual acute leukemia after therapy has proven its importance to monitor response to therapy and provide prognostic information. In this protocol, the flow cytometric detection of MRD and LSCs is outlined herein, with an emphasis on the leukemia-associated immunophenotype (LAIP) and LSC markers.
