title: Synthesis of cathepsin B by cells derived from the HL60 promyelocytic leukaemia cell line.
abstract: Cells of the human promyelocytic HL60 line were induced to differentiate into granulocyte-like cells with dimethylsulphoxide (DMSO) or macrophage-like cells with 12-0-tetradecanoylphorbol-13-acetate (TPA). The synthesis of Cathepsin B by these cells was studied by immunoperoxidase staining and assay of cell lysates using the fluorimetric substrate benzoyloxycarbonyl-phenylanalyl-arginine-4-methyl-7-coumarylamide. Only 2-5% of the uninduced HL60 cells and DMSO-induced cells were immunohistochemically positive for Cathepsin B, compared with over 80% of the TPA-induced cells. Cathepsin B activity was lowest in the lysates of uninduced HL60s. DMSO-induced cells contained 1.5-2-fold the enzyme activity of HL60s and TPA-induced cell lysates demonstrated 5-14-fold the activity of uninduced HL60s. Induction of Cathepsin B synthesis was therefore associated with differentiation of the promyelocytes into cells of the monocyte/macrophage type, but not granulocyte-like cells. Cathepsin B was located immunohistochemically in human palatine tonsils. The enzyme was only demonstrated within macrophages in these tissues. Cathepsin B may therefore be a useful immunohistochemical marker for malignant and nonmalignant cells of the monocyte/macrophage lineage.
mesh_terms: D002401:Cathepsin B; D002403:Cathepsins / Q000032:analysis / Q000096:biosynthesis*; D002454:Cell Differentiation; D002460:Cell Line; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D006098:Granulocytes / Q000201:enzymology*; D006801:Humans; D007124:Immunoenzyme Techniques; D015470:Leukemia, Myeloid, Acute; D008264:Macrophages / Q000201:enzymology*; D014066:Palatine Tonsil / Q000201:enzymology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D002403:Cathepsins; D002401:Cathepsin B; D013755:Tetradecanoylphorbol Acetate; D004121:Dimethyl Sulfoxide