Diagnostic role of inflammatory and anti‐inflammatory cytokines and effector molecules of cytotoxic <scp>T</scp> lymphocytes in tuberculous pleural effusion

Abstract

BACKGROUND AND OBJECTIVE: Early diagnosis of tuberculous pleural effusion (TPE) remains difficult. While some inflammatory markers in pleural effusion (PE) are helpful in diagnosis, the roles of anti-inflammatory cytokines and effector molecules of cytotoxic T lymphocytes have not been investigated. METHODS: Lymphocyte-predominant exudative PE samples were assayed for inflammatory and anti-inflammatory cytokines and effector molecules of cytotoxic T lymphocytes. Logistic regression analysis was used to predict the probability of TPE and identify independently associated factors. Receiver operating characteristic (ROC) curve analysis was applied to determine the optimal cut-off value for the predicted probability. RESULTS: Of 95 patients enrolled, 35 had TPE, 46 had malignant PE and 14 had PE due to other aetiologies. Interferon-γ (IFN-γ), adenosine deaminase (ADA), decoy receptor (DcR) 3, monocyte chemo-attractant protein (MCP)-1, IFN-induced protein (IP)-10, granzyme A and perforin were higher in TPE than in PE of other aetiologies. By logistic regression analysis, IFN-γ ≥ 75 pg/mL, ADA ≥ 40 IU/mL, DcR3 ≥ 9.3 ng/mL and soluble tumour necrosis factor receptor 1 (TNF-sR1) ≥ 3.2 ng/mL were independent factors associated with TPE. The predicted probability based on the four predictors had an area under the ROC curve of 0.920, with 82.9% sensitivity and 86.7% specificity under the cut-off value of 0.303. In the TPE group, patients with positive PE/pleural culture for Mycobacterium tuberculosis had higher pleural IFN-γ, MCP-1, IP-10 and perforin than those with positive sputum but negative PE culture. CONCLUSIONS: While pleural interferon-γ and ADA are conventional markers for diagnosing TPE, simultaneous measurements of DcR3 and TNF-sR1 can improve the diagnostic efficacy.