Abstract
The kinetics, specificity and morphology of cytolethal responses have been studied in human glucocorticoid-sensitive and -insensitive lymphoid cell lines (HLCL) and fibroblasts following treatment with high (10(-3)M) and low (10(-6)M) doses of steroid. The high dose cytolethal response appears non-specific occurring in all cell lines with every steroid tested. By contrast, the low dose (pharmacological) cytolethal response requires an active glucocorticoid and a sensitive HLCL. However, both high and low concentrations of steroid induce virtually identical morphological changes in dying cells and similar changes can be induced in cells killed by deliberate feed exhaustion. Although the morphological features in each case resemble apoptosis, the "programmed" physiological form of cell death, the intracellular events leading to cytolysis seem likely to differ. The earliest morphological changes presaging cell death comprise rounding up of cells and condensation of nuclear chromatin. Nuclear changes progress rapidly thereafter and appear to result from detachment of chromatin from the nuclear matrix. The low dose cytolethal response requires the continuous presence of glucocorticoid for periods in excess of 24h, prior to which cell growth appears unaffected. The constancy of this latent interval suggests glucocorticoids may influence some replication control mechanism unrelated initially to macromolecular biosynthesis.
Highlights
The glucocorticoid-sensitive human lymphoid cell line CCRF-CEM-C7 (Norman & Thompson, 1977) was cloned originally from a glucocorticoidinsensitive line CCRF-CEM established from a patient with acute lymphoblastic leukaemia (Foley et al, 1965)
Cell lines were grown at 37°C in suspension culture in conical glass flasks or in plastic test tubes in RPMI 1640 medium supplemented with 10% heat-inactivated (56°C for 1 h) donor calf serum (Gibco, Paisley, Scotland), morpholinopropane sulphonic acid buffer (MOPS: 2.62 gl- 1; Hopkin and Williams Ltd., Essex, England) penicillin (100 IU ml -1) and streptomycin sulphate (100,ug ml-1)
At low concentrations of hormone (10-6M) only the sensitive human glucocorticoid-sensitive and -insensitive lymphoid cell lines (HLCL) (CCRF-CEMC7) shows significant cytolethal responses (>75% cells killed after 96 h treatment)
Summary
The glucocorticoid-sensitive human lymphoid cell line CCRF-CEM-C7 (Norman & Thompson, 1977) was cloned originally from a glucocorticoidinsensitive line CCRF-CEM established from a patient with acute lymphoblastic leukaemia (Foley et al, 1965). The original clone was kindly provided by Dr M. The parent glucocorticoid-resistant line (CCRF-CEM) was used for comparison. Cell lines were grown at 37°C in suspension culture in conical glass flasks or in plastic test tubes in RPMI 1640 medium supplemented with 10% heat-inactivated (56°C for 1 h) donor calf serum (Gibco, Paisley, Scotland), morpholinopropane sulphonic acid buffer (MOPS: 2.62 gl- 1; Hopkin and Williams Ltd., Essex, England) penicillin (100 IU ml -1) and streptomycin sulphate (100 ,ug ml-1). Human fibroblasts (Flow 1000: Flow Laboratories Ltd., Irvine, Scotland) were grown in the same medium in Falcon flasks
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