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Studies on in vitro colony formation by mouse bone marrow cells using different inflammatory pleural exudates.
Abstract:
An inflammatory exudate obtained in Swiss mice 3 hours after intrapleural injection of dextran was able to increase the number of cultivated peritoneal macrophages in S phase. This exudate was also able to stimulate the formation of colonies from mice bone marrow progenitors of macrophages and granulocytes in methylcellulose culture. The stimulating activity of this acute inflammatory exudate was compared with that of colony stimulating factor (GM.CSF). The qualitative and quantitative results showed that the biological activity of the mitogenic factor of this inflammatory exudate, inflammatory mitogenic factor (IMF) was very close to GM.CSF at optimal concentration, but when used at the same concentration, the exudate was less active than GM.CSF. A stimulating activity was also found with another inflammatory pleural exudate induced by calcium pyrophosphate. The comparative kinetics of the action of the two exudates on CFUc appeared alike but the rise was earlier with calcium pyrophosphate. These results suggest the release of a growth factor for monocyte-macrophage in different acute inflammatory exudates.
Insights
Acute inflammatory exudates stimulate macrophage proliferation and colony formation. These exudates contain a mitogenic factor (IMF) comparable to, but less potent than, granulocyte-macrophage colony-stimulating factor (GM-CSF).
Area of Science:
- Immunology
- Cell Biology
- Hematopoiesis
Background:
- Inflammatory exudates are complex biological fluids containing various mediators.
- The role of acute inflammatory exudates in regulating hematopoiesis is not fully understood.
- Colony-stimulating factors (CSFs) are crucial for myeloid cell development.
Purpose of the Study:
- To investigate the hematopoietic stimulating activity of acute inflammatory exudates.
- To compare the activity of inflammatory exudates with granulocyte-macrophage colony-stimulating factor (GM-CSF).
- To identify potential growth factors involved in monocyte-macrophage regulation during inflammation.
Main Methods:
- Intrapleural injection of dextran or calcium pyrophosphate in Swiss mice to induce inflammatory exudates.
- Cultivation of peritoneal macrophages to assess proliferation (S phase).
- Methylcellulose culture of bone marrow progenitors to evaluate colony formation (macrophages and granulocytes).
- Comparison of exudate activity with purified GM-CSF.
Main Results:
- Dextran-induced inflammatory exudate increased macrophage proliferation and stimulated colony formation from bone marrow progenitors.
- The mitogenic factor in the exudate (IMF) showed activity similar to GM-CSF at optimal concentrations but was less potent at equal concentrations.
- Another inflammatory exudate (calcium pyrophosphate-induced) also demonstrated stimulating activity on colony-forming units (CFUc), with similar kinetics but an earlier rise.
Conclusions:
- Acute inflammatory exudates contain factors that promote monocyte-macrophage proliferation and differentiation.
- The biological activity of these exudates is comparable to, yet distinct from, established colony-stimulating factors like GM-CSF.
- These findings suggest the release of endogenous growth factors for monocyte-macrophage lineages during acute inflammation.