Correlation between flow cytometric identification of CD33-positive cells and morphological evaluation of myeloblasts in bone marrow of patients with acute myeloblastic leukemia

Determination of the percentage of myeloblasts in bone marrow is important for the evaluation of acute myeloblastic leukemia ( AML) and related disorders. Using flow cytometry with a CD45-blast gate ( FCM/CD45), 226 bone marrow aspiration samples serially collected from 71 patients with de novo AML were analyzed. Bone marrow smears were evaluated independently by pathologists who did not know the corresponding flow cytometric data in advance. Patients received remission induction followed by consolidation. The CD33+ cell percentages evaluated by FCM/CD45 were strongly correlated to the myeloblast percentages determined by microscopic examination ( r=0.8360, p<0.001). When only samples containing leukemic cells demonstrated by chromosomal or fluorescence in situ hybridization ( FISH) analysis after induction were evaluated, positive correlations were found between CD33+ cell percentages determined by FCM/CD45 and myeloblast percentages determined by morphology ( r=0.672, p<0.001). The identification of CD33+ cells by FCM/CD45 is useful for the evaluation of bone marrow myeloblasts in AML.