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Bactericidal/permeability-increasing protein release in whole blood ex vivo: strong induction by lipopolysaccharide
M A Dentener1, G J Francot, P S Hiemstra
1Department of Pulmonology, University of Limburg, Maastricht, Netherlands.
Abstract:
In this study, the release of bactericidal/permeability-increasing protein (BPI), which is stored in polymorphonuclear leukocytes (PMNL), was analyzed in a whole blood ex vivo system. Of the microbial products tested, lipopolysaccharide (LPS) most potently induced BPI release; FMLP, serum-treated zymosan (STZ), and lipoteichoic acid (LTA) also induced BPI release. In addition, the inflammatory mediator tumor necrosis factor (TNF)-alpha potently activated PMNL in whole blood, via TNF receptor p55, to release BPI, whereas interleukin (IL)-1, IL-8, platelet activating factor, and C5a were poor inducers of BPI release. STZ and phorbol myristate acetate, but not LPS, FMLP, or LTA, stimulated isolated PMNL to release BPI. BPI was released in comparable magnitude with the azurophilic granule protein elastase. Furthermore, both proteins were released with similar kinetics, which started within 30 min after onset of stimulation and lasted 1-4 h.
Insights
Bactericidal/permeability-increasing protein (BPI) release from white blood cells (PMNL) was studied. Microbial products like LPS and inflammatory mediators such as TNF-alpha potently triggered BPI release in whole blood.
Area of Science:
- Immunology
- Cell Biology
Background:
- Polymorphonuclear leukocytes (PMNL) store bactericidal/permeability-increasing protein (BPI).
- Understanding BPI release mechanisms is crucial for inflammatory and immune responses.
Purpose of the Study:
- To investigate the induction of BPI release from PMNL in a whole blood ex vivo system.
- To identify specific microbial products and inflammatory mediators that trigger BPI release.
Main Methods:
- Analysis of BPI release in a whole blood ex vivo model.
- Stimulation of PMNL with various microbial products (LPS, FMLP, STZ, LTA) and inflammatory mediators (TNF-alpha, IL-1, IL-8, PAF, C5a).
- Comparison of BPI release kinetics with elastase release in isolated PMNL.
Main Results:
- Lipopolysaccharide (LPS) was the most potent inducer of BPI release in whole blood.
- Tumor necrosis factor-alpha (TNF-alpha) also potently induced BPI release via TNF receptor p55.
- Isolated PMNL released BPI upon stimulation with STZ and phorbol myristate acetate, but not LPS, FMLP, or LTA.
- BPI and elastase were released with comparable kinetics, starting within 30 minutes and lasting 1-4 hours.
Conclusions:
- Specific microbial components and inflammatory mediators differentially regulate BPI release from PMNL.
- BPI release is a rapid response of PMNL to certain inflammatory stimuli.
- The findings provide insights into the innate immune response involving BPI.