Flow cytometric analysis is useful for deciding the therapeutic method in adult leukemia

Abstract

Flow cytometric analysis has become essential in the diagnosis and management of hematologic neoplasms. The cellular markers commonly used for immunophenotyping of leukemia are CD13, CD33, CD117,cytoplasmic myeloperoxidase for myeloid lineage, CD10, CD19, CD20, CD22, CD23, cytoplasmic CD79a for B-cell, CD2, CD3, CD7, CD4, CD8, cytoplasmic CD3, TCRα/β, TCRγ/δfor T-cell, CD16, CD56 for NK-cell lineage, CD41, CD42, CD61 for megakaryocytic lineage and CD235a for erythroid lineage. CD34, HLA-DR and TdT are also used. Immunophenotyping is especially necessary for the diagnosis of biphenotypic acute leukemia and FAB M0 of AML. Blasts of AML M0 are histochemically negative for myeloperoxidase, but flow cytometry (FCM) demonstrates myeloid markers such as CD13, CD33 and myeloperoxidase. Biphenotypic acute leukemia is characterized by the presence of blasts coexpressing lymphoid and myeloid antigens. In addition, FCM is useful in diagnosing the extramedullary infiltration of leukemia by analysing specimens such as ascites, pleural effusion, cerebrospinal fluid and solid tissue specimens. The evaluation of mininal residual disease (MRD) by FCM is useful for leukemic blasts with antigenic abnormalities, such as AML with B- or T-cell associated markers or CD56. Sensitivity of 10^-2～10^-4 can be achieved by identifying blasts on SSC/CD45 dot plots and data acquisition from a large number of events.