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S-protein is synthesized by human monocytes and macrophages in vitro
G Hetland1, H B Pettersen, T E Mollnes
1Bloodbank, Ullevål Hospital, Oslo, Norway.
Abstract:
Human monocytes and alveolar and peritoneal macrophages were cultured in serum-free medium with or without endotoxin (ET), agarose beads, or cycloheximide. The cell culture supernatants were collected after various intervals and examined by a monoclonal anti-S-protein antibody in Western blot and in a solid-phase enzyme immunoassay. We found that the phagocytes synthesize and secrete S-protein. ET stimulation or prolonged incubation of the cells did not favour S-protein production, which was inhibited by cycloheximide. Agarose stimulation increased the S-protein level in supernatants from monocyte but not from macrophage cultures.
Insights
Human phagocytes, including monocytes and macrophages, synthesize and secrete S-protein. Production is inhibited by cycloheximide, with agarose stimulating monocytes but not macrophages.
Area of Science:
- Immunology
- Cell Biology
- Protein Synthesis
Background:
- Monocytes and macrophages are key immune cells involved in host defense.
- S-protein is a component relevant to cellular processes and immune responses.
- Understanding the regulation of S-protein production by phagocytes is crucial for immunological research.
Purpose of the Study:
- To investigate the synthesis and secretion of S-protein by human monocytes and macrophages.
- To determine the effects of endotoxin (ET), agarose beads, and cycloheximide on S-protein production.
- To differentiate the regulatory mechanisms of S-protein production between monocytes and macrophages.
Main Methods:
- Human monocytes, alveolar macrophages, and peritoneal macrophages were cultured in serum-free medium.
- Cultures were treated with endotoxin (ET), agarose beads, or cycloheximide.
- Cell culture supernatants were analyzed for S-protein using Western blot and enzyme immunoassay with a monoclonal anti-S-protein antibody.
Main Results:
- Human monocytes and macrophages were confirmed to synthesize and secrete S-protein.
- Endotoxin (ET) stimulation and prolonged cell incubation did not enhance S-protein production.
- Cycloheximide significantly inhibited S-protein production, indicating de novo synthesis.
- Agarose bead stimulation increased S-protein levels in monocyte cultures but not in macrophage cultures.
Conclusions:
- Phagocytes actively synthesize and secrete S-protein, a process dependent on protein synthesis.
- Monocyte S-protein production is differentially regulated compared to macrophages, particularly in response to particulate stimuli like agarose.
- These findings provide insights into the cellular regulation of S-protein in innate immune cells.