Interleukin-16 in tuberculous and malignant pleural effusions

Area of Science:

• Immunology
• Cell Biology
• Respiratory Medicine

Background:

• Interleukin-16 (IL-16) is a cytokine with known immunomodulatory functions.
• Its role in pleural effusions, particularly in distinguishing between tuberculous and malignant causes, requires further investigation.

Purpose of the Study:

• To investigate the presence and levels of IL-16 in pleural effusions.
• To correlate IL-16 concentrations with cytological parameters.
• To assess the chemoattractant activity of IL-16 on CD4+ T-lymphocytes.

Main Methods:

• Quantification of IL-16 in pleural effusions from patients with tuberculous pleurisy and lung cancer.
• Analysis of total nucleated cell and differential counts.
• Three-colour flow cytometry to determine T-lymphocyte subsets.
• In vitro assessment of IL-16 chemoattractant activity for CD4+ T-lymphocytes.

Main Results:

• IL-16 levels were significantly elevated in tuberculous pleural effusions compared to malignant effusions.
• A positive correlation was observed between IL-16 levels and the number of CD4+ T-cells.
• Pleural fluid demonstrated chemoattractant properties for CD4+ T-cells in vitro.
• Intrapleural IL-16 administration led to increased CD4+ T-cell infiltration.

Conclusions:

• Interleukin-16 is present in pleural effusions and is significantly higher in tuberculous cases.
• IL-16 exhibits chemoattractant activity for CD4+ T-lymphocytes, contributing to their infiltration into the pleural space.
• While elevated in tuberculous effusions, IL-16 levels alone are insufficient for definitive diagnosis due to overlapping ranges.