ABSTRACT
Immunophenotyping by flow cytometry (FC) plays an important role in the diagnosis and subclassification of acute leukemias. FC is a quick process, allowing diagnosis within one or two hours after the specimen reaches the laboratory. FC is much more sensitive and specific than morphology and not only allows differentiating between acute myeloid leukemia (AML) and acute lymphoblastic leukemia, but in many cases aids in further subclassification of AML. Hematopoietic stem cells in the bone marrow express CD34, HLA-DR, CD38, and CD117. CD133 is a stem cell marker which proceeds and overlaps with expression of CD34. The most valuable markers to differentiate between myeloblasts and lymphoblasts are CD13/CD33/CD117, CD10/CD19/cytoplasmic CD79a, and cytoplasmic CD3. Cytochemical staining with myeloperoxidase is often helpful in the subclassification of acute leukemia.
