The effect of lidocaine on in vitro adhesion and migration of equine neutrophils.

This research studied how lidocaine, a common local anesthetic, affects the movement and attachment of neutrophils, a type of white blood cell, in horses.

Methodology

• Neutrophils were obtained from horse blood using a process called Percoll-gradient centrifugation, a technique designed to isolate particular cells.
• These neutrophils were then exposed to varying concentrations of lidocaine, ranging from 0.1 to 1000 micrograms per milliliter, and left to incubate for 30 minutes at a temperature of 37 degrees Celcius.
• After being dyed with a fluorescent compound called calcein, the neutrophils’ adhesion and migration were tested. This was done by stimulating them with three different substances: Leukotriene B4 (LTB4), Platelet-activating factor (PAF), or Interleukin 8 (IL-8).

Findings

• All three substances were found to significantly increase neutrophil adhesion, meaning they helped neutrophils stick to other substances more effectively.
• Adhesion was increased most significantly when the neutrophils were treated with 1mg/mL lidocaine and then stimulated with IL-8. This was also true when compared to the same test using lower concentrations of lidocaine.
• Leukotriene B4-stimulated adhesion was also significantly higher with a concentration of 1mg/mL lidocaine compared to 5 micrograms/mL.
• Movement of the neutrophils was significantly increased under stimulation of IL-8.
• Migration was also significantly increased at 1mg/mL lidocaine compared to lower concentrations, when the cells were stimulated with IL-8 and Leukotriene B4.

Conclusion

• In this in vitro (laboratory, non-living) study, lidocaine did not hinder the movement or adhesion of neutrophils at therapeutic concentrations.
• In fact, higher concentrations of lidocaine appeared to increase both movement and adhesion.

This implies that lidocaine, at least at therapeutic levels, will not negatively impact the neutrophils’ ability to adhere or migrate, which are important functions in immune response. Higher levels might even enhance these functions, though further studies would be required to confirm this finding.