Does gradient isolation preserve equine neutrophil viability and oxidative function for up to six hours?

Overview

• This research evaluated whether neutrophils isolated from horse blood retain their viability and functional ability to produce reactive oxygen species for up to six hours after isolation using a gradient method.
• The study compared isolated neutrophils with those in whole blood to verify if the isolation process affects their antioxidant function, particularly their respiratory burst activity.

Research Objectives

• To test the viability of equine neutrophils isolated from whole blood over a 6-hour time period.
• To assess the oxidative function of these neutrophils by measuring their ability to reduce nitroblue tetrazolium (NBT), indicating respiratory burst capability.
• To compare functional results between isolated neutrophils and neutrophils in whole blood to understand if isolation impairs function.

Methodology

• Isolation Method: Neutrophils were isolated from equine whole blood using a density gradient medium called Histopaque®.
• Time Points: Neutrophil viability and function were evaluated at baseline (0 hours), 3 hours, and 6 hours post-isolation.
• Function Assessment: The nitroblue tetrazolium (NBT) reduction test was used to measure respiratory burst. This assay detects reactive oxygen species (ROS) generated by neutrophils, which reduce the NBT dye to a blue formazan precipitate.
• Viability Assessment: Both automated cell counts and manual microscopic techniques were employed to determine neutrophil concentration and viability at each time point.

Key Findings

• Neutrophils isolated via gradient centrifugation maintained their ability to undergo respiratory burst, as indicated by consistent NBT reduction over the entire 6-hour period.
• There were no significant differences in oxidative function among the three time points tested (0 h, 3 h, 6 h), demonstrating stability of neutrophil function post-isolation.
• Cell counts and viability assessments confirmed that neutrophils remain viable for up to 6 hours following the isolation procedure.
• Comparisons indicated no significant loss of antioxidant function in isolated cells compared to cells evaluated directly from whole blood, supporting the hypothesis that isolation does not impair functional evaluation.

Significance and Implications

• This study validates the use of gradient centrifugation with Histopaque® as a reliable method for isolating equine neutrophils without compromising their viability or functional capacity for at least 6 hours.
• Researchers and veterinary clinicians can confidently assess neutrophil oxidative burst activity using isolated cells, even several hours post-isolation, facilitating flexible and accurate laboratory analyses.
• These findings support the broader application of isolated neutrophil assays in studying equine immune responses and pathologies related to oxidative stress or inflammation.