Fractionation of a Differentiated Mouse Leukemia Cell Line by Discontinuous Ficoll-Urografin Density Gradients

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Abstract
The Ficoll-Urografin density gradient method was used to separate differentiated mouse myeloid [leukemia] cells (M1) and the properties of the fractionated cell populations were investigated. During differentiation in vitro, M1 cells produced large adherent cells. These adherent cells showed an increased cell size and a decreased ratio of nucleus size to cell size (N/C ratio) in comparison with untreated M1 cells and nonadherent cells. With discontinuous Ficoll-Urografin density gradient centrifugation, adherent cells could be separated into subfractions with low N/C ratios (d = 1.033-1.054, rich in macrophage-like cells); those with intermediate N/C ratios (d = 1.054-1.059, rich in cells in the intermediate stages of differentiation); and those with high N/C ratios (d = 1.059-1.067, rich in myeloblastic cells). Almost all the untreated M1 cells and nonadherent cells were banded in the high density region (d = 1.059-1.067). Both phagocytic and lysozymic activities were highest in the lowest density band. Elevated lysosomal enzyme activity in the highest density fraction of the fractionated cells indicates that these cells may differ from M1 cells in their biological activity.
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