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Updated: Aug 16, 2026
Functional Characterization of Regulatory Macrophages That Inhibit Graft-reactive Immunity
Published on: June 7, 2017
Thymidine-dependent effect of granulocyte-derived inhibitor on granulocyte-macrophage progenitor cells (GM-CFC)
A Bøyum1, J Helgestad, D Løvhaug
1Norwegian Defence Research Establishment, Division for Environmental Toxicology, Kjeller.
Abstract:
We have compared the effect of granulocyte extract (GRE) on proliferation of hemopoietic cells from various sources, using two different cultures media, CMRL 1066 and McCoy 5A. GRE caused a strong (80-90%) inhibition of granulocyte-macrophage colony forming cells (GM-CFC) in cultures with medium CMRL 1066. GM-CFC in human blood and human and mouse bone marrow were equally sensitive to the inhibitor. The inhibitor had a maximal effect in the concentration range corresponding to GRE from 2 x 10(5) to 2 x 10(6) cells per 1 ml culture dish. At higher GRE concentration the inhibition was reduced. GM-CFC from human blood and mouse marrow were suppressed in cultures with McCoy's medium as well, but to a lesser extent than in CMRL 1066 cultures. On the other hand, in cultures with human bone marrow cells (BMC) and McCoy's medium, GRE had no inhibitory effect. CMRL 1066 medium contains a number of components not present in McCoy's medium. In a systematic study where these substances were added one by one to McCoy's medium we found that inhibition by GRE depended upon the presence of thymidine. At a thymidine concentration of 3 x 10(-5) mol/l GRE strongly suppressed GM-CFC in human blood and bone marrow. This thymidine concentration itself had no effect. Other nucleosides or components of the CMRL 1066 did not potentiate the suppressive effect of GRE.
Insights
Granulocyte extract (GRE) strongly inhibits hemopoietic cell proliferation, particularly granulocyte-macrophage colony forming cells (GM-CFC). This inhibition is dependent on thymidine in the culture medium, revealing a key factor in GRE
Area of Science:
- Hematology
- Cell Biology
- Biochemistry
Background:
- Hemopoietic cell proliferation is crucial for blood formation.
- Granulocyte extract (GRE) is investigated for its effects on hemopoiesis.
- Culture media composition can influence cellular responses.
Purpose of the Study:
- To compare the effect of GRE on hemopoietic cell proliferation using different culture media.
- To identify factors in culture media that modulate GRE's inhibitory effect.
- To determine the optimal conditions for GRE-induced inhibition of GM-CFC.
Main Methods:
- Culturing hemopoietic cells from human blood, human bone marrow, and mouse bone marrow.
- Assessing proliferation of granulocyte-macrophage colony forming cells (GM-CFC) using CMRL 1066 and McCoy 5A media.
- Systematically adding components of CMRL 1066 to McCoy 5A medium to identify essential factors for GRE inhibition.
Main Results:
- GRE significantly inhibited GM-CFC proliferation (80-90%) in CMRL 1066 medium across all tested sources.
- GRE's inhibitory effect was concentration-dependent, with maximal inhibition observed at specific GRE concentrations.
- Thymidine, at a concentration of 3 x 10(-5) mol/l, was identified as a critical component in CMRL 1066 that potentiated GRE's suppression of GM-CFC.
Conclusions:
- GRE is a potent inhibitor of GM-CFC proliferation.
- Thymidine is essential for GRE to exert its maximal inhibitory effect on GM-CFC in human blood and bone marrow.
- The findings highlight the importance of culture medium composition in studying the effects of GRE on hemopoiesis.
