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Updated: May 11, 2026

Characterization of Immune Cells and Proinflammatory Mediators in the Pulmonary Environment
Published on: June 24, 2020
Interleukin-18 is up-regulated in infectious pleural effusions
Nikoletta Rovina1, Efrossini Dima, Ioannis Psallidas
11st Department of Critical Care Medicine & Pulmonary Services, GP Livanos and M Simou Laboratories, Medical School of Athens University, Evangelismos Hospital, Athens, Greece. nikrovina@med.uoa.gr
Interleukin-18 (IL-18) is elevated in pleural effusions, particularly in empyema, and drives neutrophilic inflammation in the pleural space. This cytokine is linked to the severity of pleural inflammation across various causes.
Area of Science:
- Pulmonology
- Immunology
- Inflammation Research
Background:
- Pleural effusions (PEs) encompass diverse conditions, including heart failure, malignancy, infection, and inflammation.
- Interleukin-18 (IL-18) is a pro-inflammatory cytokine with known roles in immune responses.
- Understanding IL-18's role in the pleural space is crucial for diagnosing and managing PEs.
Purpose of the Study:
- To investigate pleural and systemic expression of IL-18 in patients with various PEs.
- To determine the effects of IL-18 in the mouse pleural space.
- To correlate IL-18 levels with markers of pleural inflammation.
Main Methods:
- Quantified pleural fluid (PF) and serum IL-18 using ELISA in 160 patients with diverse PEs.
- Administered intrapleural IL-18 in mice to assess pleural inflammation via pleural lavage.
- Analyzed correlations between PF IL-18 and inflammatory markers (neutrophils, LDH, glucose, pH).
Main Results:
- Highest PF IL-18 levels were found in parapneumonic effusions/empyemas; lowest in miscellaneous exudates and transudates.
- PF IL-18 was significantly higher in empyemas than uncomplicated or complicated parapneumonic effusions.
- PF IL-18 correlated with markers of acute pleural inflammation (neutrophils, LDH, glucose, pH) and IL-18 induced neutrophilic inflammation in mice.
Conclusions:
- IL-18 is associated with neutrophilic pleural inflammation intensity in PEs.
- IL-18 is upregulated in the pleural space in empyema.
- IL-18 stimulates neutrophil accumulation in the mouse pleura, suggesting a role in empyema pathogenesis.
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