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Suppression of chemotaxis to corneal inflammation by nitrous oxide
B J Kripke1, A Kupferman, K C Luu
1School of Medicine, University of Southern California.
Abstract:
Immune competency is depressed in the perioperative period. The role of anesthetic agents in immune reactivity remains unclear. The chemotactic migration of polymorphonuclear leukocytes (PMNs) to the cornea of rabbits injured by clove oil was studied. PMNs were previously radiolabeled with tritiated (3H) thymidine. Immediately following injury, the rabbits entered isolation chambers and breathed either air or air containing 10%, 20% or 40% nitrous oxide (N2O) for 24 hours. After sacrifice, the radioactivity of a 10 mm corneal button, removed by trephination, was determined by scintillation counting technique. Peripheral blood was obtained for hemoglobin, white cell and platelet count. The N2O dosage affected on the migration of PMNs to the cornea. 3H was decreased 15.4% by 20% N2O and 38.8% for 40% N2O-exposed rabbits. Peripheral blood values did not differ. N2O can suppress chemotaxis of PMNs in the rabbit, thereby adversely affecting the inflammatory component of immune defense.
Insights
Nitrous oxide (N2O) impairs the immune system's ability to fight inflammation. This study shows N2O suppresses polymorphonuclear leukocyte (PMN) migration to injured corneas in rabbits, potentially weakening immune defense.
Area of Science:
- Immunology
- Anesthesiology
- Ophthalmology
Background:
- Perioperative immune depression is a known clinical issue.
- The specific impact of anesthetic agents like nitrous oxide (N2O) on immune function is not fully understood.
- Polymorphonuclear leukocytes (PMNs) play a critical role in the inflammatory response.
Purpose of the Study:
- To investigate the effect of varying concentrations of nitrous oxide (N2O) on the chemotactic migration of PMNs to an injured cornea in a rabbit model.
- To assess whether N2O affects peripheral blood cell counts.
Main Methods:
- Rabbit corneal injury was induced using clove oil.
- Rabbits inhaled air with 0%, 10%, 20%, or 40% N2O for 24 hours.
- Radiolabeled PMNs (using tritiated thymidine) were used to quantify migration to the cornea via scintillation counting.
- Peripheral blood was analyzed for hemoglobin, white blood cell, and platelet counts.
Main Results:
- Nitrous oxide exposure significantly reduced PMN migration to the injured cornea.
- A dose-dependent effect was observed: 20% N2O decreased radioactivity by 15.4%, and 40% N2O by 38.8%.
- No significant differences were found in peripheral blood cell counts across groups.
Conclusions:
- Nitrous oxide can suppress PMN chemotaxis in rabbits.
- This suppression of PMN migration may adversely affect the inflammatory component of the immune defense during the perioperative period.
- Further research is warranted to understand the clinical implications of N2O's immunosuppressive effects.