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Phagocytosis stimulates the release of a slow reacting substance in cultured macrophages
Abstract:
1 A slow-reacting substance (SRS) was released from non-elicited mouse peritoneal macrophages during phagocytosis of zymosan particles, whereas no detectable SRS was produced by resting cells. 2 The macrophage SRS induced a delayed and slow contraction of the guinea-pig ileum but not of the chick rectum. 3 The myotonic activity was antagonized by low concentrations of FPL 55712 (sodium 7-[3-(4-acetyl-3-hydroxy-2-propylphenoxy)-2-hydroxypropoxy]-4-oxo-8-propyl-4H-1 -benzopyran-2 carboxylate) but was not affected by mepyramine or hyoscine, and was not associated with tachyphylaxis. 4 SRS release was increased by indomethacin and was abolished by the lipoxygenase and cyclooxygenase inhibitor, BW755C (3-amino-1-[m-(trifluoromethyl)-phenyl]-2-pyrazoline). 5 Addition of exogenous arachidonic acid or cysteine enhanced SRS production.
Insights
Mouse macrophages release a slow-reacting substance (SRS) during phagocytosis. This SRS causes muscle contractions, and its production is influenced by specific inhibitors and substrates like arachidonic acid.
Area of Science:
- Immunology
- Pharmacology
- Cell Biology
Background:
- Macrophages play a key role in immune responses.
- Phagocytosis is a critical cellular process for immune cells.
- Slow-reacting substances (SRS) are involved in inflammatory processes.
Purpose of the Study:
- To investigate the release of SRS from mouse peritoneal macrophages during phagocytosis.
- To characterize the biological activity of macrophage-derived SRS.
- To identify factors influencing SRS production and release.
Main Methods:
- Phagocytosis of zymosan particles by mouse peritoneal macrophages.
- Assay of SRS release.
- Measurement of guinea-pig ileum and chick rectum contraction.
- Pharmacological inhibition of SRS production using indomethacin and BW755C.
- Effect of exogenous arachidonic acid and cysteine on SRS production.
Main Results:
- Non-elicited mouse peritoneal macrophages released SRS during zymosan particle phagocytosis.
- Macrophage SRS induced delayed, slow contraction of guinea-pig ileum, but not chick rectum.
- SRS-induced myotonic activity was antagonized by FPL 55712, unaffected by mepyramine or hyoscine, and showed no tachyphylaxis.
- Indomethacin increased SRS release; BW755C abolished it.
- Exogenous arachidonic acid and cysteine enhanced SRS production.
Conclusions:
- Mouse peritoneal macrophages produce SRS upon phagocytic stimulation.
- Macrophage SRS exhibits specific smooth muscle contracting activity.
- SRS production is modulated by cyclooxygenase and lipoxygenase pathways and substrate availability.