Tumor necrosis factor production and receptor expression by a human malignant glioma cell line, D54-MG.
Human malignant gliomas possess some of the same immune-related functions as astrocytes do. For instance, they are capable of secreting various immunoregulatory molecules and expressing HLA-DR antigens on their surface. The human malignant glioma cell line, D54-MG, was used to investigate the proliferative effects of tumor necrosis factor-alpha (TNF-alpha) and the expression of specific surface receptors for TNF-alpha. Additionally, we were interested in examining whether D54-MG cells are capable of synthesizing and secreting biologically active TNF-alpha. D54-MG cells responded in a mitogenic fashion upon incubation with TNF-alpha for 48 h under serum-free conditions. 125I-labeled TNF-alpha was used in this study to investigate the expression of receptors specific for TNF-alpha on D54-MG cells. Scatchard analysis of our receptor binding data produced curvilinear plots indicating there are two distinct receptor sites for TNF-alpha. From these data, we calculated that there are approximately 3500 high affinity and 24,666 low affinity binding sites per cell. Pretreating these cells with interferon-gamma (IFN-gamma) resulted in a 2-fold increase in the number of high affinity binding sites and a moderate increase in the number of low affinity binding sites, with no appreciable change in binding affinity (Kd) of either site. D54-MG cells were unable to constitutively secrete TNF-alpha; however, upon stimulation, these cells synthesize and secrete biologically active TNF-alpha. Polyclonal antisera reactive with human macrophage-derived TNF-alpha neutralized the cytotoxicity of D54-MG-derived TNF-alpha, demonstrating that the cytotoxic activity was in fact due to TNF-alpha. Our observations indicate that TNF-alpha could act in an autocrine fashion to induce the proliferation of this malignant glioma cell line and that TNF-alpha exerts its effect by binding to specific TNF-alpha receptors whose expression was enhanced by IFN-gamma.
Bethea
J R
JR
Department of Neurology, University of Alabama, Birmingham 35294.
Gillespie
G Y
GY
Chung
I Y
IY
Benveniste
E N
EN
D002455:Cell Division / Q000187:drug effects; D005910:Glioma / Q000276:immunology* / Q000473:pathology; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D011956:Receptors, Cell Surface / Q000032:analysis* / Q000187:drug effects; D018124:Receptors, Tumor Necrosis Factor; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis* / Q000378:metabolism / Q000494:pharmacology
D008070:Lipopolysaccharides; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D013755:Tetradecanoylphorbol Acetate