title: Regulation of tumor necrosis factor-alpha production and gene expression in monocytes.
abstract: Tumor necrosis factor-alpha (TNF-alpha), produced predominantly by activated monocytes/macrophages, inhibits leukemic cell growth and may contribute to a graft-versus-leukemia effect after marrow transplantation. We examined the recombinant cytokines interferon (IFN)-alpha, IFN-gamma, granulocyte- macrophage colony-stimulating factor (GM-CSF), and macrophage colony-stimulating factor (M-CSF), alone or in combination, for their ability to induce monocytes from normal donors and patients after marrow grafting to express TNF-alpha mRNA and secrete TNF-alpha bioactivity. Monocytes were isolated from peripheral blood by Percoll separation of E-rosette-negative cells, and cultured with cytokines under non-adherent, endotoxin-free conditions. TNF-alpha transcripts were undetectable in freshly isolated monocytes from normal donors. Only the combination of IFN-gamma/GM-CSF was consistently capable of inducing substantial TNF-alpha mRNA transcript levels and protein secretion. Levels of TNF-alpha transcripts induced by IFN-gamma/GM-CSF were maintained for at least 36 h, in contrast to lipopolysaccharide (LPS) stimulation which caused TNF-alpha mRNA levels to peak after 2 h and decline rapidly thereafter. IFN-gamma/GM-CSF was also capable of inducing a prolonged (at least 48 h) secretion of TNF-alpha bioactivity. In contrast, greater than 80% of the total TNF-alpha bioactivity secreted by LPS-stimulated monocytes was secreted in the first 8 h. When monocytes were incubated with IFN-gamma alone ('priming'), washed and then exposed to GM-CSF, both TNF-alpha mRNA expression and TNF-alpha protein production occurred.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Leukemia/Bone Marrow Transplantation Program of British Columbia, Vancouver, Canada.
authors.forename: F R
authors.initials: FR
authors.lastname: Kohn
authors.forename: G L
authors.initials: GL
authors.lastname: Phillips
authors.forename: H G
authors.initials: HG
authors.lastname: Klingemann
mesh_terms: D000293:Adolescent; D000328:Adult; D015152:Blotting, Northern; D016026:Bone Marrow Transplantation; D002469:Cell Separation; D005260:Female; D005786:Gene Expression Regulation / Q000235:genetics*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000502:physiology; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects; D014184:Transplantation, Homologous; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics* / Q000378:metabolism*
chemical_list: D008070:Lipopolysaccharides; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D016178:Granulocyte-Macrophage Colony-Stimulating Factor