title: Time-course of changes in the plasma-membrane lipid bilayer and cellular ultrastructure induced by tumour necrosis factor-alpha in K 562 and Daudi cells.
abstract: The time-course of changes in the plasma-membrane lipid bilayer induced by tumour necrosis factor-alpha (TNF) were investigated in cultured cells using spin-label electron-spin-resonance techniques. Treatment of K 562 cells, a human chronic myelocytic leukaemia cell line, in suspension culture with TNF for up to 6 h caused an initial increase in cell-membrane fluidity, which returned to the control level after 12 h of treatment. After 24 h of treatment, the cell-membrane fluidity had decreased and this decrease was maintained after 48 h of treatment. In Daudi cells, a human malignant lymphoma cell line, TNF, did not induce any changes in cell-membrane fluidity, indicating that the effect of TNF on membrane structure is cell-specific. The early and transient change in membrane fluidity in K 562 cells is probably related to signal generation, while the later, persistent change may reflect the phenotype of TNF-treated cells, in particular, changes in the plasma membrane-cytoplasmic complex. Histochemical electron microscopic studies indicated that the membrane fluidity changes induced by TNF have an ultrastructural correlate.
authors.affiliation: First Department of Surgery, Okayama University Medical School, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Marutaka
authors.forename: H
authors.initials: H
authors.lastname: Iwagaki
authors.forename: K
authors.initials: K
authors.lastname: Mizukawa
authors.forename: N
authors.initials: N
authors.lastname: Tanaka
authors.forename: K
authors.initials: K
authors.lastname: Orita
mesh_terms: D002462:Cell Membrane / Q000187:drug effects*; D004578:Electron Spin Resonance Spectroscopy; D006801:Humans; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000378:metabolism; D008223:Lymphoma / Q000378:metabolism; D008560:Membrane Fluidity / Q000187:drug effects; D008854:Microscopy, Electron; D013997:Time Factors; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D014409:Tumor Necrosis Factor-alpha