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Kinetics of changes in peritoneal cell populations following acute inflammation
M J Melnicoff1, P K Horan, P S Morahan
1Department of Immunology, Smith Kline & French Laboratories, King of Prussia, Pennsylvania 19406.
Abstract:
The kinetics of macrophage (M phi) recruitment to the peritoneum following the induction of acute inflammation by thioglycollate broth (TG) was evaluated after prelabeling resident M phi with the fluorescent cell tracking dye, PKH-1. Most of the PKH-1-labeled resident M phi disappeared from the recoverable peritoneal cell population within the first hour after injection of TG. This disappearance coincided with the inflammatory influx of neutrophils (PMNs) and was sustained for at least 5 days after administration of TG, although the PMN number had returned to resident levels by this time. PKH-1-labeled peritoneal M phi were observed again in most animals at 7 days after injection of TG. The number of labeled M phi recovered at 7 days was approximately twice the number of resident peritoneal M phi in control animals which did not receive the TG broth. These additional M phi may include progeny of either the resident M phi or other local M phi precursors, such as omental M phi, which were labeled by the PKH-1 injection.
Insights
Resident macrophages rapidly disappear during acute inflammation after thioglycollate broth (TG) induction. Labeled macrophages reappear by day 7, suggesting proliferation or recruitment of local precursors to peritoneal inflammation.
Area of Science:
- Immunology
- Cell Biology
Background:
- Acute inflammation involves complex cellular dynamics in the peritoneal cavity.
- Understanding macrophage (M phi) kinetics is crucial for inflammatory response studies.
Purpose of the Study:
- To investigate the fate of resident peritoneal macrophages during acute inflammation induced by thioglycollate broth (TG).
- To track the recruitment and potential proliferation of macrophages in the peritoneum.
Main Methods:
- Resident peritoneal macrophages were prelabeled with the fluorescent dye PKH-1.
- Acute inflammation was induced using thioglycollate broth (TG).
- Peritoneal cells were collected and analyzed at various time points post-induction.
Main Results:
- Most PKH-1-labeled resident macrophages disappeared within the first hour after TG injection, coinciding with neutrophil influx.
- This disappearance was sustained for at least 5 days, even after neutrophil numbers normalized.
- Labeled macrophages reappeared by day 7, with numbers approximately double that of control resident macrophages.
Conclusions:
- Resident macrophages are depleted early in the inflammatory response to TG.
- The reappearance of labeled macrophages suggests proliferation of resident cells or recruitment of local precursors like omental macrophages.