Changes in cell surface glycoproteins and antigens during differentiation of the human myeloid leukemia cell lines ML-1, ML-2, and HL-60.
Two recently derived human myeloid leukemia cell lines, ML-1 and ML-2, were induced to differentiate by treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA) or with retinoic acid for 5 to 12 days. They were then compared with similarly treated promyelocytic HL-60 cells. TPA-treated ML-1 and ML-2 cells became firmly surface adhesive with a fibroblastoid morphology, while TPA-treated HL-60 cells adhered as rounded macrophages. In contrast, retinoic acid induced only slight morphological changes in all three cell lines. The differentiation-related alterations of the surface membrane glycoproteins were followed by polyacrylamide gel electrophoresis after surface labeling by the periodate-NaB3H4 or galactose oxidase-NaB3H4 methods. The expression of surface membrane differentiation antigens was analyzed with a panel of monoclonal antibodies against myeloid, myelomonocytic, monocytic, and granulocytic determinants using FACS IV flow cytometry. The acquisition of surface adhesiveness by TPA-treated ML-1 and ML-2 cells coincided with the appearance of membrane surface proteins of varying molecular weights, ranging between 90,000 and 155,000, which were not labeled in untreated ML-1 and ML-2 cells. These findings and the results obtained by monoclonal antibody staining and FACS analysis indicate that treatment of the myeloid lines ML-1, ML-2, and HL-60 by TPA induced the expression of antigenic and membrane molecular features compatible with a monocytic-macrophage phenotype, while treatment by retinoic acid induced granulocytic differentiation. The ML-1 and ML-2 cells offer interesting models for studies on the membrane molecular events occurring when nonadherent, monocytic cells become surface adherent.