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Spontaneous nitroblue-tetrazolium (NBT) reduction related to granulocyte priming and activation
T Wikström1, M Braide, U Bagge
1Department of Surgery, University of Göteborg, Sweden.
Abstract:
The aim of the present study was to explore the relationship between the increasing level of spontaneous NBT-reduction and the tendency for PMNs to marginate during experimental hemorrhagic shock in rats. Rat PMNs, isolated on Percoll density gradients or suspended in blood, were examined by chemiluminescence (CL), NBT-test and by their CD-18 expression and F-actin formation. The NBT-test generally produced higher numbers of activated PMNs when the cells were suspended in buffer than in whole blood, probably due to the scavenging properties of blood. The level of spontaneous NBT-reduction of PMNs in blood correlated with the magnitude of the NBT-response to f-MLP stimulation in blood and buffer. On the contrary, there were no significant correlations between spontaneous NBT reduction, CD18 expression and F-actin content. Thus, high levels of spontaneous NBT reduction in blood were associated with priming of the separated PMNs rather than increased rigidity (F-actin) or adhesiveness (CD18).
Insights
Spontaneous NBT-reduction in neutrophils (PMNs) during hemorrhagic shock indicates cell priming, not increased rigidity or adhesiveness. This finding offers insights into neutrophil activation during critical illness.
Area of Science:
- Immunology
- Physiology
Background:
- Neutrophil activation is critical in inflammatory responses, including hemorrhagic shock.
- Polymorphonuclear neutrophils (PMNs) play a key role in the inflammatory cascade.
- Understanding PMN behavior during shock is crucial for therapeutic interventions.
Purpose of the Study:
- To investigate the relationship between spontaneous NBT-reduction and PMN margination during experimental hemorrhagic shock in rats.
- To assess the correlation between spontaneous NBT reduction and PMN activation markers (CD18 expression, F-actin formation).
Main Methods:
- Isolation of rat PMNs using Percoll density gradients and suspension in blood.
- Assessment of PMN activation via chemiluminescence (CL), Nitro blue tetrazolium (NBT) test, CD18 expression, and F-actin formation.
- Analysis of spontaneous NBT-reduction and response to f-MLP stimulation.
Main Results:
- The NBT test yielded higher activated PMN counts in buffer compared to whole blood, likely due to blood's scavenging effects.
- Spontaneous NBT-reduction in PMNs correlated with their response to f-MLP stimulation.
- No significant correlation was found between spontaneous NBT reduction and CD18 expression or F-actin content.
Conclusions:
- High spontaneous NBT reduction in neutrophils during hemorrhagic shock suggests a 'primed' state rather than increased adhesiveness or rigidity.
- These findings contribute to understanding neutrophil functional changes in critical illness.
- The study highlights the importance of considering the cellular environment (blood vs. buffer) when assessing PMN activation.