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Regulation of interleukin 1 gene expression by adherence and lipopolysaccharide
Abstract:
Murine peritoneal exudate cells (PEC), analyzed immediately after isolation, did not express detectable IL 1 activity or IL 1-specific mRNA. Stimulation of these cells by adherence induced the expression of intracellular, membrane, and extracellular IL 1 activities within 4 hr. Analysis of mRNA from these cells showed a concurrent induction of both IL 1 alpha and IL 1 beta mRNA within 1 hr. However, this stimulation of IL 1 expression was transient, since PEC cultured for 5 days no longer expressed IL 1 bioactivity or specific mRNA. Stimulation of these quiescent cells with bacterial lipopolysaccharide induced the re-expression of intracellular, membrane, and extracellular IL 1 activities as well as IL 1 alpha and IL 1 beta mRNA. We found no qualitative difference in the degree or rate of induction of IL 1 alpha compared with IL 1 beta mRNA. These results indicate that resting macrophages are IL 1 negative, and that the IL 1 inducing stimuli used in this study act transiently to increase the levels of IL 1 alpha and IL 1 beta mRNA.
Insights
Resting macrophages do not produce interleukin-1 (IL-1). Adherence or lipopolysaccharide stimulation transiently increases IL-1 alpha and IL-1 beta mRNA and activity in these cells.
Area of Science:
- Immunology
- Cell Biology
Background:
- Interleukin-1 (IL-1) is a key cytokine in immune responses.
- The regulation of IL-1 expression in macrophages is not fully understood.
Purpose of the Study:
- To investigate the regulation of IL-1 alpha and IL-1 beta expression in murine peritoneal exudate cells (PECs).
- To determine the effect of adherence and lipopolysaccharide (LPS) stimulation on IL-1 production.
Main Methods:
- Isolation and culture of murine PECs.
- Measurement of intracellular, membrane, and extracellular IL-1 activity.
- Analysis of IL-1 alpha and IL-1 beta mRNA levels using RT-PCR.
Main Results:
- Resting PECs showed no detectable IL-1 activity or mRNA.
- Adherence induced intracellular, membrane, and extracellular IL-1 activities and IL-1 alpha/beta mRNA within 1-4 hours.
- This induction was transient, with IL-1 expression ceasing after 5 days of culture.
- LPS stimulation re-induced IL-1 expression in quiescent PECs.
- No qualitative difference was observed in the induction of IL-1 alpha versus IL-1 beta mRNA.
Conclusions:
- Resting macrophages are IL-1 negative.
- Stimuli like adherence and LPS transiently induce IL-1 alpha and IL-1 beta mRNA and bioactivity.
- Macrophage IL-1 expression is tightly regulated and stimulus-dependent.