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Updated: Aug 30, 2026
Noninvasive Sampling of Mucosal Lining Fluid for the Quantification of In Vivo Upper Airway Immune-mediator Levels
Published on: August 7, 2017
Pleural fluid levels of interleukin-5 and eosinophils are closely correlated
K H Mohamed1, Amany I Abdelhamid, Y C Gary Lee
1Department of Chest Diseases, Zagazig University Hospital, Zagazig, Egypt.
Background:
The mechanisms responsible for the accumulation of eosinophils in pleural fluid are not fully understood. The purpose of this study was to evaluate the relationship between eosinophil accumulation and the levels of interleukin (IL)-5, IL-3, and granulocyte/macrophage colony-simulating factor (GM-CSF) in pleural effusions.
Methods:
We evaluated 30 patients with eosinophilic pleural effusions (eosinophil count > 10% nucleated cells in pleural fluid) and 10 patients with noneosinophilic pleural effusions. The patients with eosinophilic pleural effusions included 22 patients with post-coronary artery bypass graft surgery pleural effusions and 8 patients with eosinophilic pleural effusions caused by other causes. IL-5, IL-3, and GM-CSF in all pleural fluids were measured using enzyme-linked immunosorbent assay kits.
Results:
The mean level of IL-5 in eosinophilic pleural effusions (283.1 +/- 341.6 pg/mL) was significantly (p < 0.025) higher than that in the noneosinophilic effusions (28.2 +/- 19.0 pg/mL). The absolute eosinophil count and percentage correlated significantly with the level of IL-5 in all patients (r = 0.55, p < 0.001, and r = 0.54, p < 0.001, respectively). There was no significant correlation between IL-5 levels and RBC counts in all patients (r = 0.24, p > 0.05). GM-CSF and IL-3 levels were below the detectable range in all pleural fluids.
Conclusion:
There is a significant relationship between the levels of IL-5 in pleural fluid and the total number and percentage of eosinophils in the pleural fluid. IL-5 seems to be related to the eosinophil accumulation associated with blood or air in the pleural space and other eosinophilic pleural effusions.
Insights
Interleukin-5 (IL-5) is significantly elevated in eosinophilic pleural effusions, correlating with increased eosinophil counts. This suggests IL-5 plays a key role in eosinophil accumulation within the pleural space.
Area of Science:
- Pulmonology
- Immunology
- Biochemistry
Background:
- Mechanisms driving eosinophil accumulation in pleural fluid remain unclear.
- Understanding these mechanisms is crucial for diagnosing and treating pleural effusions.
Purpose of the Study:
- To investigate the relationship between eosinophil counts in pleural effusions and levels of key cytokines.
- Specifically examining Interleukin-5 (IL-5), IL-3, and Granulocyte/Macrophage Colony-Simulating Factor (GM-CSF).
Main Methods:
- Enzyme-linked immunosorbent assay (ELISA) was used to measure cytokine levels in pleural fluid.
- Study included 30 patients with eosinophilic pleural effusions and 10 with noneosinophilic effusions.
- Eosinophilic effusions were defined by >10% eosinophils in nucleated cells.
Main Results:
- Mean IL-5 levels were significantly higher in eosinophilic effusions (283.1 pg/mL) compared to noneosinophilic effusions (28.2 pg/mL).
- A significant positive correlation was found between absolute eosinophil count and IL-5 levels (r=0.55, p<0.001).
- IL-3 and GM-CSF levels were below detection limits in all samples.
Conclusions:
- Elevated IL-5 levels in pleural fluid are strongly associated with eosinophil accumulation.
- IL-5 appears to be a critical mediator in eosinophilic pleural effusions, including those related to blood or air exposure.
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