Myeloid and Megakaryocytic Properties of K-562 Cell Lines1

The expression of myeloid and megakaryocytic markers of differentiation has been studied in one K-562 cell subline, in its clones, and in the original cell line. Cytotoxicity, electron micros copy, immunofluorescence studies with a panel of polyclonal and monoclonal antibodies, and radioimmunoassays were performed on K-562 cells before and after induction with hemin, sodium butyrate, and 12-O-tetradecanoylphorbol-13-acetate. Myeloid membrane markers were present in all K-562 cell lines. Only the early granulopoietic cell surface markers were expressed in 75 to 95% of the cells, while none of the late membrane markers was detected. In contrast, neither the early (myeloperoxidase) nor late (lactoferrin) cytoplasmic markers were present. Thus, K562 cells showed a membrane phenotype similar to that of a normal or leukemic promyelocyte but lacking myeloperoxidase. Membrane megakaryocytic markers, such as platelet glycoprotein Ilia and platelet peroxidase, were also detected in K-562 cells. However, some other early megakaryocytic markers, such as platelet glycoprotein Ib, Factor VIII-R-Ag, and platelet Factor 4, could not be detected by fluorescent labeling. Cloning of the cell line did not result in the selection of a unipotential cell line. These results could be explained by the expression of multilineage markers in a single cell. In all of the cell lines and clones, hemin slightly increased the expresston of the myeloid membrane markers without any modification of the megakaryocytic mark ers. Sodium butyrate and 12-O-tetradecanoylphorbol-13-acetate diminished most of the myeloid markers and very significantly increased the expression of the megakaryocytic markers.