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Induction of macrophage growth by lipoprotein
Abstract:
Cell-free tumorous ascitic fluid stimulated growth of variously induced mouse peritoneal macrophages and resident macrophages in vitro. This induction of macrophage growth by the tumorous ascitic fluid was confirmed by autoradiography. The macrophage growth-stimulating activity was stable on heating at 100 degrees C, in contrast to that of macrophage growth factor (colony stimulating factor) previously reported. This heat-stable macrophage growth-stimulating activity was recovered in the lipoprotein fraction of tumorous ascitic fluid. The lipoprotein from heat-treated normal mouse serum also induced growth of macrophages. These results indicate that lipoprotein can induce macrophage proliferation, at least in vitro.
Insights
Tumorous ascitic fluid contains heat-stable lipoproteins that stimulate macrophage proliferation in vitro. This finding suggests lipoproteins may play a role in tumor-associated macrophage activation.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Tumorous ascitic fluid (TAF) is known to influence immune cells.
- Macrophages are crucial immune cells involved in various biological processes.
- Previous studies identified heat-labile factors like colony-stimulating factor in TAF.
Purpose of the Study:
- To investigate the in vitro effects of cell-free tumorous ascitic fluid on macrophage proliferation.
- To characterize the nature of the macrophage growth-stimulating activity present in TAF.
Main Methods:
- In vitro culture of mouse peritoneal macrophages and resident macrophages.
- Stimulation of macrophage growth using cell-free TAF.
- Autoradiography to confirm macrophage proliferation.
- Heat treatment of TAF to assess activity stability.
- Fractionation of TAF to isolate active components, including lipoproteins.
Main Results:
- Cell-free TAF significantly stimulated the growth of both induced and resident mouse macrophages in vitro.
- The macrophage growth-stimulating activity in TAF was resistant to heat treatment at 100°C.
- This heat-stable activity was localized to the lipoprotein fraction of TAF.
- Lipoproteins isolated from normal mouse serum also demonstrated macrophage growth-inducing properties.
Conclusions:
- Lipoproteins present in tumorous ascitic fluid possess heat-stable macrophage growth-stimulating activity.
- Lipoprotein appears to be a key factor in inducing macrophage proliferation in vitro.
- These findings suggest a potential role for lipoproteins in modulating macrophage behavior in the tumor microenvironment.