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C M Bunce

Publications and source records attributed to C M Bunce.

48 records · Page 3Linked to original sources
PubMed1986

Cathepsin B synthesis by the HL60 promyelocytic cell line: effects of stimulating agents and anti-inflammatory compounds.

Cathepsin B synthesis by the human HL60 promyelocyte cell line was investigated by immunohistochemistry and by the assay of the enzyme in cell lysates using a fluorimetric substrate. HL60 cells were shown to produce cathepsin B in response to treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA). Intracellular levels of cathepsin B and immunohistochemical staining of the enzyme were related to time in culture with increasing concentrations of TPA from 1 nmol/1 to 8.0 nmol/1. Synthesis of cathepsin B was associated with TPA-induced phagocytic activity of cells in culture, expression of alpha-naphthyl acetate esterase and reduced cell division. Cathepsin B production was, therefore, related to differentiation of the HL60 promyelocytes into mature macrophage-like cells. Cathepsin B activity in HL60 cell lysates was significantly increased by incubation of the cells with 10 micrograms/ml endotoxin (lipopolysaccharide) from Escherichia coli, but not carrageenan. The production of cathepsin B by TPA-induced HL60 cells was significantly reduced by 0.25 mumol/1 dexamethasone and the non-steroidal anti-inflammatory compound 4-(6-methoxy-2-naphthyl)-butan-2-one but not by indomethacin. The HL60 promyelocytic cell line is a useful model for the study of factors affecting proteinase synthesis by human mononuclear phagocytes.

Anti-Inflammatory Agents↗
PubMed1986

Expression of a 215,000-dalton nuclear envelope protein decreases during cell maturation.

The monoclonal antibody AGF2.3 identifies a nuclear envelope protein expressed at high levels in most transformed cell lines and weakly expressed in or absent from normal tissues and primary cell cultures. Here we report that expression of AGF2.3 antigen relates to the maturation status of cells. When HL60 cells were induced to mature loss of AGF2.3 antigen correlated with the appearance of neutrophils in culture. Acute myeloid leukaemia cells were intensely labelled by AGF2.3 antibody whereas chronic myeloid leukaemia cells were weakly reactive. Staining of tonsil epithelium showed a progressive loss of antigen during epithelial cell maturation. High levels of AGF2.3 antigen in most permanent cell lines suggest that such lines represent transformation of immature cells.

Antibodies, Monoclonal↗
PubMed1985

A combination of calcium ionophore and 12-O-tetradecanoyl-phorbol-13-acetate (TPA) stimulates the growth of purified resting B cells.

In this study we investigated whether the calcium ionophores A23187 and ionomycin can act synergistically with the phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA) to stimulate the growth of resting B lymphocytes purified from human tonsil cells. Ionomycin, A23187, and TPA added separately to cultures at doses of 0.4-1.6 micrograms/ml, 0.2-0.8 micrograms/ml, and 0.05-0.25 ng/ml respectively, did not induce DNA synthesis in resting B lymphocytes. In contrast, calcium ionophores at concentrations of 0.4-1.6 micrograms/ml ionomycin and 0.2-0.8 micrograms/ml A23187, in the presence of 0.05-4 ng/ml TPA, induced marked DNA synthesis and B-cell proliferation, as shown by analyses of incorporation of [3H]thymidine, growth kinetics, and the percentage of cells in the S and G2 + M phases of the cell cycle. These results show that the synergistic effects of calcium ionophores and TPA can bypass the requirement for antigen and exogenous growth factors in B-cell activation. These observations are similar to those obtained from studies of T lymphocytes by other workers.

B-Lymphocytes↗
PubMed1983

Isolation and characterisation of dimethylsulphoxide resistant variants from the human promyeloid cell line HL60.

The HL60 line can be induced to differentiate into neutrophils by 1.25% dimethylsulphoxide (DMSO) or monocytes by 12-O-tetradecanoylphorbol-13-acetate (TPA). Seven variants of this line have been isolated which do not respond to 1.25% DMSO. Five of these lines can be induced to mature into neutrophils using DMSO concentrations of 1.75% (HL60 m2, m4, Sp1 and Ast3) and 2.0% (HL60 Ast25). Two lines, HL60 Ast1 and 4, showed minimal differentiation even at a concentration of 2.0% DMSO, and 2.25% DMSO was toxic to these cells. Of the seven variant lines, HL60 Ast3, Ast4 and Sp1 failed to differentiate into monocytes in response to TPA. Sublines from HL60 that either require higher concentrations of DMSO to induce maturation or fail to differentiate into neutrophils, such as those described above, can be used to investigate how genetically determined properties within HL60 cells affect the ability to mature into neutrophils.

Antigens, Surface↗
PubMed1982

Variant cell lines from the human promyelocyte line HL60.

The continuous human promyeloid cell line HL60 may be induced to differentiate into neutrophils by the presence of 1.25% dimethylsulphoxide (DMSO) and related compounds [4]. When treated with 12-O-tetradecanoylphorbol-13-acetate (TPA), the cells exhibit may features characteristic of monocytes/macrophages [13]. In both cases, the induced HL60 cells lose their proliferative ability. The availability of this inducible cell line has led to an increasing number of studies aimed at dissecting the process of myeloid differentiation. However, the correct interpretation of such studies may only be reached through the use of appropriate cellular controls; specifically, variant HL60 cell lines which do not differentiate in response to the inducing agents. Here we report the isolation and characterization of two variant cell lines of HL60 which do not differentiate in the presence of 1.25% dimethylsulphoxide but still respond to TPA. Comparison of these HL60 variants with the parental line should facilitate the elucidation of molecular events which regulate myeloid differentiation.

Cell Division↗
PubMed1982

Studies of human myeloid antigens using monoclonal antibodies and variant lines from the promyeloid cell line HL60.

Monoclonal antibodies were produced using mice immunized with the human promyeloid cell line HL60. Two antibodies are described which identify antigens selectively expressed by myeloid cells. Studies using normal bone marrow and myeloid leukaemia cells demonstrated that one of these antibodies (AGF4.48) identifies an antigen expressed throughout the promyeloid to neutrophil stages of maturation. In contrast, the second antibody (AGF4.36) identifies an antigen expressed at the promyeloid to metamyeloid stages and is absent from most blood neutrophils. The HL60 line can be induced to differentiate into neutrophils by 1 . 25% dimethylsulphoxide (DMSO) (Collins et al., 1978). Variant lines from HL60, unresponsive to 1 . 25% DMSO, lack the 'transient' myeloid antigen (AGF4.36) and show a reduced expression of the myeloid antigen (AGF4.48). The variant lines can be induced to mature using higher DMSO concentrations (1 . 5-1 . 75%) and do not express the 'transient' antigen (AGF4.36) during their maturation. The use of these lines in studies of myelopoiesis is discussed.

Animals↗