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Mouse macrophages release a neutrophil chemotactic mediator following stimulation by staphylococcal enterotoxin type
I A Desouza1, S Hyslop, C F Franco-Penteado
1Department of Physiology and Biophysics, Institute of Biology, State University of Campinas, SP, Brazil. ivanidesouza@uol.com.br
Objective And Design:
To examine the role of macrophages in the neutrophil migration induced by staphylococcal enterotoxin type A (SEA) in mice.
Materials And Methods:
Peritoneal macrophages were harvested from male Swiss mice pre-treated with thioglycollate. After adhering to plastic tissue culture dishes, the cells were washed and incubated with RPMI or SEA (0.62-2.5 microg/ml) and washed again prior to further incubation with RPMI alone. The medium was then collected, sterilized and assayed for promigratory activity in the mouse peritoneal cavity.
Results:
Mouse macrophage monolayers stimulated with SEA secreted a thermolabile neutrophil chemotactic component (MNCC-SEA) with a molecular mass >100 kDa (by ultrafiltration). This release was dose- and time-dependent and was inhibited by dexamethasone but not by indomethacin or BW755C. Dexamethasone, indomethacin, BWA4C, BW755C, BN52021, cimetidine and SR48968 had no effect on the neutrophil migration induced by MNCC-SEA while capsaicin and SR 140333 reduced this phenomenon.
Conclusions:
Macrophages play a key role in the neutrophil recruitment induced by SEA probably by releasing an MNCC-SEA that presumably induces neutrophil migration via a mechanism mediated by substance P.
Insights
Macrophages release a neutrophil chemotactic factor (MNCC-SEA) in response to staphylococcal enterotoxin A (SEA), driving neutrophil migration.
Area of Science:
- Immunology
- Cell Biology
Background:
- Neutrophil recruitment is crucial for host defense.
- Staphylococcal enterotoxin A (SEA) is a potent immune stimulant.
Purpose of the Study:
- To investigate the role of macrophages in SEA-induced neutrophil migration.
- To identify mediators involved in this process.
Main Methods:
- Peritoneal macrophages from mice were stimulated with SEA.
- Supernatants containing secreted factors were collected and tested for neutrophil chemotactic activity.
- Inhibitors were used to probe the mechanism of action.
Main Results:
- SEA-stimulated macrophages released a heat-labile neutrophil chemotactic component (MNCC-SEA) >100 kDa.
- Release was dose- and time-dependent and inhibited by dexamethasone.
- Capsaicin and SR 140333 modulated MNCC-SEA-induced migration.
Conclusions:
- Macrophages are key players in SEA-induced neutrophil recruitment.
- Macrophages release MNCC-SEA, which likely mediates neutrophil migration via substance P pathways.