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Peritoneal macrophages from patients on CAPD show an increased capacity to secrete interleukin-1 beta during
M W Fieren1, G J van den Bemd, I L Bonta
1Department of Internal Medicine (I), University Hospital Dijkzigt, Erasmus University Rotterdam.
Abstract:
The in vitro release of interleukin-1 beta (IL-1 beta) by peritoneal macrophages from CAPD patients was studied during 16 infection free periods (16 patients) and 13 episodes of peritonitis (10 patients) using an ELISA. Without exogeneous stimulation with LPS, peritoneal macrophages released the same amounts of IL-1 beta. irrespective if they were obtained during an infection free period (473 +/- 92 pg/ml 24h, means +/- SEM) or during peritonitis (324 +/- 125 pg/ml). However, in response to a dose of 5 micrograms/ml of LPS, peritoneal macrophages released significantly more (p less than 0.005) IL-1 beta during peritonitis (6155 +/- 1743 pg/ml). These findings show that during peritonitis, peritoneal macrophages are primed in vivo to release more IL-1 beta in vitro after stimulation with LPS, indicating that activation of peritoneal macrophages for IL-1 beta secretion occurs stepwise.
Insights
Peritoneal macrophages in patients undergoing continuous ambulatory peritoneal dialysis (CAPD) show heightened interleukin-1 beta (IL-1 beta) release during peritonitis episodes when stimulated. This suggests a stepwise activation of these immune cells in response to infection.
Area of Science:
- Immunology
- Nephrology
Background:
- Peritoneal macrophages play a crucial role in the host defense against infection in patients undergoing continuous ambulatory peritoneal dialysis (CAPD).
- Interleukin-1 beta (IL-1 beta) is a key pro-inflammatory cytokine involved in immune responses.
Purpose of the Study:
- To investigate the in vitro release of IL-1 beta by peritoneal macrophages from CAPD patients during infection-free periods and episodes of peritonitis.
- To determine if peritoneal macrophages are primed in vivo during peritonitis to enhance IL-1 beta secretion upon stimulation.
Main Methods:
- Peritoneal macrophages were collected from CAPD patients during both infection-free periods and active peritonitis.
- An enzyme-linked immunosorbent assay (ELISA) was used to quantify IL-1 beta release.
- Macrophages were tested for IL-1 beta release both without exogenous stimulation and after stimulation with lipopolysaccharide (LPS).
Main Results:
- In the absence of lipopolysaccharide (LPS) stimulation, peritoneal macrophages released similar amounts of IL-1 beta regardless of whether they were obtained during infection-free periods or peritonitis.
- Upon stimulation with LPS (5 micrograms/ml), peritoneal macrophages collected during peritonitis released significantly higher amounts of IL-1 beta compared to those from infection-free periods (p < 0.005).
- These results indicate an enhanced in vitro response to LPS in macrophages from patients with peritonitis.
Conclusions:
- Peritoneal macrophages in CAPD patients are primed in vivo during peritonitis to release greater amounts of IL-1 beta when stimulated with LPS.
- The findings suggest a stepwise activation process for peritoneal macrophages concerning IL-1 beta secretion, particularly in the context of infection.