title: Differential expression of tumor necrosis factor and interleukin-6 by peritoneal macrophages in vivo and in culture.
abstract: To investigate the differences in cytokine regulation in vitro as compared to in vivo, we examined the synthesis of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) by peritoneal macrophages in response to lipopolysaccharide (LPS). Mice (CBA/J) were primed with an intraperitoneal injection of complete Freund's adjuvant and after 2 weeks, peritoneal cells were harvested for culture or mice were injected intraperitoneally with LPS for in vivo studies. In ascites fluid, TNF-alpha peaked 1 hour after LPS and returned to baseline levels by 4 hours. In contrast, TNF-alpha in the media reached maximum at 7 hours. Expression of TNF-alpha messenger (m)RNA in vivo was rapid but transient, as levels peaked at 15 minutes and returned to baseline 1 hour after LPS. In contrast, TNF-alpha mRNA in vitro became maximal at 1 hour, but remained elevated to 5 hours after LPS. In vivo, IL-6 in ascites fluid peaked at 2 hours, whereas in vitro, IL-6 continued increasing to 24 hours. In vivo, IL-6 mRNA reached maximum at 30 minutes, but fell below baseline by 1.5 hours after LPS. In contrast, IL-6 mRNA in vitro was sustained at maximal expression between 5 to 9 hours after LPS. These results demonstrate that both TNF-alpha and IL-6 synthesis is more rapid in vivo than in vitro. The rapid kinetics of cytokine expression in vivo must considered when designing strategies to inhibit cytokine action in vivo.
authors.affiliation: Department of Pathology, University of Michigan Medical School, Ann Arbor.
authors.forename: G K
authors.initials: GK
authors.lastname: Wollenberg
authors.forename: L E
authors.initials: LE
authors.lastname: DeForge
authors.forename: G
authors.initials: G
authors.lastname: Bolgos
authors.forename: D G
authors.initials: DG
authors.lastname: Remick
mesh_terms: D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002478:Cells, Cultured; D005260:Female; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism*; D017737:Macrophages, Peritoneal / Q000378:metabolism*; D051379:Mice; D008808:Mice, Inbred CBA; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism*
chemical_list: D015850:Interleukin-6; D015345:Oligonucleotide Probes; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha