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Peritoneal macrophages from patients on continuous ambulatory peritoneal dialysis have an increased capability to
M W Fieren1, G J van den Bemd, I L Bonta
1Department of Internal Medicine I, University Hospital Dijkzigt, Erasmus University Rotterdam, The Netherlands.
Abstract:
We have reported previously that human peritoneal macrophages collected from patients on Continuous Ambulatory Peritoneal Dialysis (CAPD) during an episode of peritonitis secrete increased amounts of interleukin-1 (IL-1), as compared to those collected during an infection free period, provided the cells were stimulated in vitro by LPS. We now report that such macrophages release also higher amounts of Tumor Necrosis Factor (TNF), if collected during peritonitis and stimulated subsequently in vitro by LPS. The increase in release of TNF was ascertained by radio-immunoassays as well as by bioassay of cytostatic effect against the highly sensitive TNF target-cell line L929 murine transformed fibroblasts. The present reported results, in addition to previously reported data on release of IL-1, indicate that induction of release of cytokines from human peritoneal macrophages is a dual stepwise process: first priming in vivo in an inflammatory environment and, secondly stimulation in vitro by LPS.
Insights
Peritoneal macrophages from Continuous Ambulatory Peritoneal Dialysis patients with peritonitis release more Tumor Necrosis Factor (TNF) and Interleukin-1 (IL-1) when stimulated. This indicates a two-step process involving in vivo priming and in vitro stimulation for cytokine release.
Area of Science:
- Immunology
- Cell Biology
- Nephrology
Background:
- Human peritoneal macrophages from Continuous Ambulatory Peritoneal Dialysis (CAPD) patients during peritonitis secrete elevated Interleukin-1 (IL-1) upon lipopolysaccharide (LPS) stimulation.
- This study investigates the release of Tumor Necrosis Factor (TNF) from these same macrophages.
Purpose of the Study:
- To determine if peritoneal macrophages from CAPD patients with peritonitis also exhibit increased Tumor Necrosis Factor (TNF) release compared to infection-free periods.
- To elucidate the mechanism of cytokine induction in peritoneal macrophages.
Main Methods:
- Collection of human peritoneal macrophages from CAPD patients during peritonitis and infection-free periods.
- In vitro stimulation of macrophages with lipopolysaccharide (LPS).
- Quantification of TNF release using radio-immunoassays and bioassays against L929 murine fibroblasts.
Main Results:
- Macrophages collected during peritonitis released significantly higher amounts of TNF when stimulated with LPS compared to those from infection-free periods.
- Radio-immunoassays and bioassays confirmed the increased TNF release.
- These findings, combined with previous IL-1 data, support a dual-step induction process.
Conclusions:
- Peritoneal macrophages from CAPD patients with peritonitis show enhanced release of both IL-1 and TNF.
- Cytokine release induction is a two-step process: in vivo inflammatory priming followed by in vitro LPS stimulation.
- This dual mechanism highlights the complex immune response in CAPD-related peritonitis.