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Human Interleukin-6 and Interleukin-6 Receptor in Pleural Effusions.

1Ayoub AA, 1El–Sayed SA, 1Soad E. Abdel Rehim, 3Abu Naglah A. and 2Abu El-Eneen SS

Departments of 1Microbiology and 2Internal Medicine, Faculty of Medicine for Girls, Al-Azhar University and 3Chest Department, Faculty of Medicine, Al-Azhar University, Cairo, Egypt.


Interleukin-6 (IL-6) is a multifunctional cytokine whose abnormal production was previously reported in pleural effusion. The clinical significance of soluble IL-6 receptors (sIL-6R) in pleural effusion is still not understood. In the present study, IL-6 and sIL-6R were measured using ELISA in exudative pleural effusion of tuberculous, malignant and postpneumonic origins and in transudative effusion secondary to heart failure, liver cirrhosis and nephropathy, to determine their diagnostic value and whether either or both could be helpful for differential diagnosis. Both IL-6 and sIL-6R were detectable in all pleural effusion with significantly higher levels in exudative compared to transudative effusion. Non significant differences in IL-6 levels were detected between exudative effusion of different origins while levels of sIL-6R were significantly higher in malignant and postpneumonic effusion compared to tuberculous effusion (P< 0.001, <0.001 respectively). Nonsignificant differences were observed between levels in effusion due to mesothelioma compared to levels in effusion due to metastasis. It was striking in this study to observe significant differences in levels of IL-6 and sIL-6R in tuberculous effusion collected from patients who did not start antituberculous treatment compared to those who started treatment (P< 0.001, <0.001 respectively). It is concluded that IL-6 and sIL-6R levels in pleural fluids are sensitive parameters to differentiate exudates from transudates and that sIL-6R can differentiate between exudative effusion of different origins.