IL-12 Is Dysregulated in Macrophages from IRF-1 and IRF-2 Knockout Mice

• Published in: The Journal of immunology (1950) 1999-08, Vol.163 (3), p.1529-1536
• Main Authors: Salkowski, Cindy A, Kopydlowski, Karen, Blanco, Jorge, Cody, M. Joshua, McNally, Ranney, Vogel, Stefanie N
• Format: Article
• Language: English
• Subjects: Animals; Consensus Sequence; DNA-Binding Proteins - genetics; Interferon Regulatory Factor-1; Interferon Regulatory Factor-2; Interferon Regulatory Factors; Interferon-gamma - biosynthesis; Interferon-gamma - immunology; Interferon-gamma - pharmacology; Interleukin-12 - biosynthesis; Interleukin-12 - genetics; Interleukin-12 - physiology; Interleukin-12 - secretion; Lipopolysaccharides - pharmacology; Macrophages, Peritoneal - immunology; Macrophages, Peritoneal - metabolism; Macrophages, Peritoneal - microbiology; Macrophages, Peritoneal - secretion; Mice; Mice, Inbred C57BL; Mice, Knockout; Phosphoproteins - genetics; Repressor Proteins - biosynthesis; RNA, Messenger - biosynthesis; Staphylococcus aureus - immunology; Transcription Factors; Up-Regulation - immunology; Zymosan - immunology
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.163.3.1529

Macrophages derived from IFN-regulatory factor-1 (IRF-1) and IRF-2 knockout (-/-) and wild-type (+/+) mice were utilized to examine the role of these transcription factors in the regulation of IL-12 mRNA and protein expression. Induction of IL-12 p40 mRNA by LPS was markedly diminished in both IRF-1(-/-) and IRF-2(-/-) macrophages. In contrast, IRF-1(-/-), but not IRF-2(-/-), macrophages exhibited impaired LPS-induced IL-12 p35 mRNA expression. The ability of IFN-gamma to augment LPS-induced IL-12 p40 mRNA further when both stimuli were present simultaneously was significantly diminished in both IRF-1(-/-) and IRF-2(-/-) macrophages, with the most profound impairment observed for IRF-1(-/-) macrophages. Reductions in IL-12 mRNA expression after stimulation with LPS or LPS plus IFN-gamma were accompanied by substantial reductions in IL-12 p40 and IL-12 p70 protein in both IRF-1(-/-) and IRF-2(-/-) macrophages. Priming IRF-1(-/-) and IRF-2(-/-) macrophages with IFN-gamma for 24 h before LPS treatment partially restored impaired IL-12 mRNA and protein production in both IRF-1(-/-) and IRF-2(-/-) macrophages. Depressed IL-12 levels were paralleled by significant reductions in IFN-gamma mRNA expression in IRF-1(-/-) and IRF-2(-/-) macrophages. These results indicate that both IRF-1 and IRF-2 are critical transcription factors in the regulation of macrophage IL-12 and consequently IFN-gamma production.