Cytokine content in pleurisy: Comparison between benign and malignant effusion

Purpose: To measure cytokine levels (TNF-α, IL-1β, MIP-1β, IL-15, GM-CSF, Fas, Fas ligand) in pleural effusion and blood of different etiologies and their relationship, and to verify whether these cytokines can be used as diagnostic markers in the differential diagnosis of pleural diseases. Methods: Seventy four patients were included and classified as follows: malignant pleural effusion (n=34), cancer with negative cytologic effusion (n=17), transudates (n=8), TB pleurisy (n=8), parapneumonic effusion (n=7). The effusions and bloods were analyzed using a monoclonal antibody enzyme-linked immunosorbent assay. Results: Both in benign and malignant diseases, IL-15, MIP-1β, Fas, Fas ligand (FasL) levels had significant correlation between blood and effusion. There was only TNF-α with significant difference between cancer and infectious diseases both in blood and effusion levels (p<0.05). IL-1β, MIP-1β levels in effusion were significant higher in TB pleurisy than malignant effusion. In infectious diseases, IL-1β and IL-15 levels in effusion were higher than in blood, but FasL was higher in blood (p <0.05). In malignant effusion, IL-15, FasL had the same phenomenon as infectious diseases, however MIP-1β level was higher in blood than in effusion (p<0.05). Conclusions: TNF-α is a immunoregulator with the significant role both in blood and effusion on the infectious pleurisy. FasL was noted as a apoptosis marker and probably play more important roles in blood than effusion, both in benign and malignant pleurisy. MIP-1β level was lower in malignant effusion and deserve further studies. Clinical Implications: TNF-α, IL-1β, and MIP-1β can be used as diagnostic markers in the differential diagnosis of tuberculous and malignant pleurisy. Lower levels of FasL and MIP-1β in effusion than blood need further studies to explain the immunological mechanism.