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Updated: Jul 5, 2026
Transfer of Manipulated Tumor-associated Neutrophils into Tumor-Bearing Mice to Study their Angiogenic Potential In Vivo
Published on: July 20, 2019
The neutrophil migration induced by tumour necrosis factor alpha in mice is unaffected by glucocorticoids
C A Cecilio1, E H Costa, P Ucelli
1Department of Microbiology and Immunology Institute of Biology UNICAMP Campinas SP 13081-970 Brazil.
Abstract:
Macrophages harvested from the peritoneal cavities of rats release a neutrophil chemotactic factor (MNCF) in response to stimulation with Gram-negative bacterial lipopolysaccharide (LPS). MNCF has been shown to be active in rats treated with dexamethasone, a glucocorticoid that usually inhibits the neutrophil migration induced in this species by interleukin (IL)-1, tumour necrosis factor alpha (TNFalpha), IL-8, C5a and leukotriene B(4) (LTB(4)). Here we report that macrophages harvested from peritoneal cavities of mice, and stimulated in vitro with LPS, also release a factor that induces neutrophil migration in dexamethasone-treated animals. This chemotactic activity was neutralized by the incubation of the LPS-stimulated macrophage supernatants with a purified polyclonal IgG anti-mouse TNFalpha. In addition, significant amounts of TNF were detected in the supernatants. The neutrophil migration induced by intraperitoneal administration of recombinant murine TNFalpha was also unaffected by pretreatment of the mice with dexamethasone. Moreover, neutrophil migration induced by intraperitoneal injection of LPS was completely blocked by pretreatment of the mice with a monoclonal antibody against murine TNFalpha. In conclusion, our results support the hypothesis that, in contrast to the role of TNF in rats (where it indirectly induces neutrophil migration), in mice, it may be an important mediator in the recruitment of neutrophils to inflammatory sites.
Insights
Macrophages stimulated with lipopolysaccharide (LPS) release a factor that recruits neutrophils, even in dexamethasone-treated mice. This activity is mediated by tumor necrosis factor alpha (TNF), highlighting its role in mouse neutrophil recruitment.
Area of Science:
- Immunology
- Cell Biology
Background:
- Macrophages release neutrophil chemotactic factors upon stimulation with lipopolysaccharide (LPS).
- Dexamethasone, a glucocorticoid, typically inhibits neutrophil migration induced by various inflammatory mediators in rats.
Purpose of the Study:
- To investigate the role of tumor necrosis factor alpha (TNF) in neutrophil recruitment in mice.
- To determine if LPS-stimulated macrophages release neutrophil chemoattractants active in dexamethasone-treated mice.
Main Methods:
- Macrophages from mouse peritoneal cavities were stimulated in vitro with LPS.
- Supernatants were tested for neutrophil chemotactic activity in dexamethasone-treated mice.
- Neutralization assays using anti-mouse TNFalpha antibodies were performed.
- TNF levels in supernatants were quantified.
- Neutrophil migration was assessed following recombinant TNFalpha or LPS administration in vivo.
Main Results:
- LPS-stimulated mouse macrophages released a factor inducing neutrophil migration in dexamethasone-treated mice.
- This activity was neutralized by anti-mouse TNFalpha antibodies, and TNF was detected in supernatants.
- Neutrophil migration induced by TNFalpha or LPS was unaffected by dexamethasone pretreatment.
- Monoclonal antibodies against TNFalpha blocked LPS-induced neutrophil migration.
Conclusions:
- In mice, TNFalpha is a significant mediator of neutrophil recruitment to inflammatory sites.
- Unlike in rats, TNFalpha appears to directly induce neutrophil migration in mice, independent of dexamethasone's inhibitory effects.
