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On the origin of peritoneal resident macrophages. I. DNA synthesis in mouse peritoneal resident macrophages
Abstract:
Mouse resident macrophages were isolated from the unstimulated peritoneal cavity at various intervals after one intravenous injection of tritiated thymidine. EM autoradiography showed that 15 min after the injection, peritoneal resident macrophages, with the characteristic localization of the peroxidatic activity in the rough endoplasmic reticulum and the nuclear envelope, had already incorporated tritiated thymidine. In the peripheral blood, monocytes with silver grains over the nuclei were seen from 12 h onwards with a maximum at 48 h. In the peritoneal cavity labelled monocytes appeared at 24 h. The peak for labelled blood monocytes was not followed by a peak for labelled peritoneal resident macrophages. The conclusion is drawn that resident macrophages from the unstimulated peritoneal cavity are able to proliferate locally.
Insights
Resident macrophages in the mouse peritoneal cavity can proliferate locally. This study used tritiated thymidine to track macrophage proliferation and found evidence of local cell division in resident macrophages.
Area of Science:
- Immunology
- Cell Biology
Background:
- Resident macrophages are crucial immune cells residing in various tissues.
- Understanding their origin and proliferation is key to immune response and tissue homeostasis.
Purpose of the Study:
- To investigate whether resident macrophages in the unstimulated peritoneal cavity proliferate locally.
- To determine the origin and kinetics of peritoneal resident macrophages.
Main Methods:
- Mice received an intravenous injection of tritiated thymidine.
- Peritoneal lavage was performed at various time points post-injection.
- Electron microscopy (EM) autoradiography was used to detect labeled cells.
Main Results:
- Peritoneal resident macrophages incorporated tritiated thymidine as early as 15 minutes post-injection.
- Labeled monocytes appeared in peripheral blood from 12 hours and in the peritoneal cavity from 24 hours.
- The peak of labeled blood monocytes was not followed by a subsequent peak in labeled peritoneal resident macrophages.
Conclusions:
- Resident macrophages in the unstimulated peritoneal cavity exhibit local proliferation.
- These findings suggest that peritoneal resident macrophages are not solely derived from blood monocyte recruitment.