PURPOSE: We have previously shown pleural injection of air causes significant eosinophilia in pleural spaces of mice. The primary objective of this study was to determine if the eosinophilia is due to the presence of air or injury caused by the injection. A secondary objective was to determine whether the volume of injected material influenced the degree of eosinophilia.
METHODS: Seventy-two wild type mice were divided into six equal groups. All mice within each group received injection of 0.1mL air, 0.1mL saline, 0.4mL air, 0.4mL saline, injury without injection, or no intervention (control). A needle, via a 0.5mm incision, was used to injure the pleura. Sacrifice was performed at 24h (hours) and 48h. Pleural inflammation was assessed by lavage.
RESULTS: Pleural eosinophilia at 24h was not significantly different between the 0.1mL injection groups compared to the injury and control groups. At 48h, 0.1mL air injection was associated with significant eosinophilia compared to the injury and control groups. Injection of 0.4mL of saline or air of resulted in a significant increase in the total percentage of eosinophils compared to the injury and control groups at 24h and 48h (p<0.001). However, the difference between the 0.4mL saline and air groups was not significant.
CONCLUSION: We conclude injury does not cause pleural eosinophilia in mice. The volume of intrapleurally injected material significantly influences the degree of eosinophilia.
CLINICAL IMPLICATIONS: Injection of air or saline intrapleurally is associated with significant eosinophilia. The underlying mechanisms need further investigation.
DISCLOSURE: Oner Dikensoy, None.