Flow cytometry immunophenotyping in integrated diagnostics of patients with newly diagnosed cytopenia: one tube 10-color 14-antibody screening panel and 3-tube extensive panel for detection of MDS-related features.

Acute leukemia, myelodysplastic syndromes (MDS), myeloproliferative neoplasms and lymphomas are the most prevalent diagnoses in adults presenting with new onset cytopenia. Here, we describe two 10-color panels of surface markers (screening and comprehensive panel) applied at the Flow Cytometry Laboratory, University Health Network, Toronto, ON, Canada. A 10-color flow cytometry is applied using the stain-lyse-wash sample preparation method. In patients with <10% blasts and no clear involvement by hematological malignancy based on cytomorphological evaluation of bone marrow (BM) smear, the recently published one-tube 10-color 14-antibody screening panel is applied. This panel allows detection of major B- and T-cell abnormalities, enumeration of cells in blast region (CD45 dim), and gives insight into myeloid BM compartment, including calculation of four-parameter score for MDS-related abnormalities. In patients who present with ≥10 - <20% blasts in blood or BM smears, a comprehensive three-tube panel of surface markers is used up front. The analysis is focused on the detection of abnormal antigen expression patterns not seen in normal/reactive BM, according to the guidelines developed by International/European LeukemiaNet Working Group for Flow Cytometry in MDS. In patients with ≥20% blasts, an additional tube is added to allow the detection of cytoplasmic markers necessary to diagnose mixed phenotype acute leukemia.