Leukemia markers expression of peripheral blood vs bone marrow blasts using flow cytometry.

BACKGROUND: Flow cytometric techniques are widely used in clinical hematology. Characterization of leukemias by immunotyping is particularly helpful when the morphology is difficult to interpret. The major advantage of using immune markers by flow cytometry is the identification of particular leukemia subtype, not recognized by morphologic criteria, which may have prognostic significance. Current literature suggests when peripheral blood (PB) is consisted of 30% blasts or higher diagnosis of acute leukemia is most likely. However, bone marrow aspiration may also be performed as a confirmatory diagnosis. Immunotyping of PB and BM in leukemias not only determine the decision making for a specific therapeutic regimen, but also is a practical prognostic indicator. MATERIAL/METHODS: We evaluated 18 patients with acute myeloid Leukemia (AML) and 13 patients with acute lymphoid leukemia (ALL). In all cases, the amount of blasts in PB was 30% or higher. Two ml PB and BM samples from each patient was collected. Following the preparation process, expression of markers was detected by using flow cytometry. The panel of monoclonal antibodies used in this study were consisted of CD3, CD7, CD5 (for T lymphocytes lineage); CD19, CD22, CD20, CD10 (for B lymphocytes lineage); CD13, CD14, CD33 (for myeloid subsets); and TDT, HLA-DR, CD45 (non lineage restricted). Expression levels of PB and BM markers were compared by using statistical analysis. RESULTS: The results showed apparent discrepancies for some markers in ALL group. However, in AML patients most of the selected markers have shown considerable correlation between PB and BM samples. Only four markers (CD13, CD14, CD45, and HLA-DR) showed positive correlation. In contrast, most markers (CD3, CD5, CD13, CD14, CD19, CD45, HLA-DR, and TdT) showed strong correlation between PB and BM samples in AML group. CONCLUSIONS: The findings of this study suggests that targeted gating strategy for blast population as well as selection of a suitable panel of monoclonal antibodies may be essential for diagnosis of leukemia resulting in similar immunotyping pattern in PB and BM. Although our results are preliminary, this can minimize the necessity of BM aspiration for leukemia patients.