Failure of lipopolysaccharides to directly trigger the chemiluminescence response of isolated equine polymorphonuclear leukocytes.
Abstract: Divergent results have been reported on the effects of lipopolysaccharides (LPS) on the activation of equine polymorphonuclear leukocytes (PMN). We therefore attempted to determine whether LPS alone can stimulate equine PMN or whether plasma factors are necessary. PMN were isolated from citrated blood on a discontinuous density gradient of Percoll. The luminol (10(-3) mol/L)-enhanced chemiluminescence (CL) of 1.25 x 10(6) cells was measured after addition of Escherichia coli LPS (0.001-10 micrograms/ml) alone or after incubation in autologous plasma (1 h, 37 degrees C). After direct stimulation with LPS, there were random variations of CL in 16 horses that were not reproducible from one sample to the next for the same horse. LPS which had been incubated in plasma gave a dose-dependent stimulation of the CL of the PMN, which did not occur if the plasma had been heat inactivated (1 h, 56 degrees C). These results indicated a role for plasma factors, which were unlikely to be cytokines, as there were no monocytes or lymphocytes in the plasma incubated with LPS, but might have been complement fragments or LPS ligands, such as LPS binding protein. Studies using specific antibodies against these factors are needed to clarify this question.
Publication Date: 1997-11-05 PubMed ID: 9345714DOI: 10.1023/a:1005938319482Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research paper investigates whether lipopolysaccharides (LPS) can independently stimulate equine polymorphonuclear leukocytes (PMN), a type of white blood cell in horses, or if plasma factors are necessary for this process.
Methodology
- PMN were separated from citrated blood via a discontinuous density gradient of Percoll, a solution used to separate cells.
- The chemiluminescence of 1.25 x 10^6 cells was then observed after they were subjected to Escherichia coli LPS alone or after incubation in autologous plasma. Chemiluminescence is a chemical reaction that emits light, and is used here as a way to measure cell activation.
- Different concentrations of LPS (0.001-10 micrograms/ml) were tested. Measurements were also made after LPS had been incubated in plasma.
Findings
- When the PMN cells were directly stimulated with LPS, the results were inconsistent. The variations of cell activation observed in the 16 horses tested were random and not reproducible, even from one sample to the next from the same horse.
- However, when LPS was incubated in plasma before being introduced to the PMN, a dose-dependent stimulation of cell activation was observed. This did not occur if the plasma had been subjected to heat inactivation, suggesting a role for certain plasma factors in LPS stimulation of PMN.
Implications
- The findings suggest that plasma factors, possibly complement fragments or LPS binding protein, might be necessary for LPS to stimulate PMN. Complement fragments are parts of the immune system’s response mechanism, and LPS binding protein facilitates the response of immune cells to LPS.
- However, it is unlikely that cytokines, a type of signaling molecule in the immune system, are involved because there were no monocytes or lymphocytes, cells that produce cytokines, in the plasma incubated with LPS.
- The exact identity of these plasma factors remains unclear, necessitating further research with specific antibodies against potential factors for clarification.
In short, this paper suggests that LPS alone cannot consistently stimulate equine PMN, and that plasma factors are likely necessary to trigger a response. It highlights a need for further research to determine exactly what these plasma factors might be.
Cite This Article
APA
Benbarek H, Deby-Dupont G, Caudron I, Deby C, Lamy M, Serteyn D.
(1997).
Failure of lipopolysaccharides to directly trigger the chemiluminescence response of isolated equine polymorphonuclear leukocytes.
Vet Res Commun, 21(7), 477-482.
https://doi.org/10.1023/a:1005938319482 Publication
Researcher Affiliations
- Service d'Anesthésiologie Générale et de Pathologie Chirurgicale des Grands Animaux, Faculté de Médecine Vétérinaire, Université de Liège, Domaine Universitaire du Sart Tilman, Belgium.
MeSH Terms
- Animals
- Dose-Response Relationship, Drug
- Escherichia coli / metabolism
- Escherichia coli / physiology
- Horses / blood
- Horses / physiology
- Lipopolysaccharides / metabolism
- Lipopolysaccharides / pharmacology
- Luminescent Measurements
- Luminol / pharmacology
- Neutrophils / cytology
- Neutrophils / drug effects
- Neutrophils / physiology
- Plasma / physiology
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