Evaluation of interferon-γ interferon-γ-inducing cytokines, and interferon-γ-inducible chemokines in tuberculous pleural effusions

Tuberculous and malignant pleural effusions are representative of lymphocytic pleural effusions. In tuberculous pleurisy, especially, T-helper type 1 (Th1) cytokines are dominant, containing, for example, high concentrations of interferon (IFN)-gamma. We focused on cytokines that induced expression of IFN-gamma and Th1 cell-specific CXC chemokines induced by IFN-gamma. We also evaluated the diagnostic utility of these markers in tuberculous pleural effusions. Forty-three patients with pleural effusions (I I with tuberculous pleuritis, 32 with malignant pleuritis) were studied. We measured the pleural concentrations of IFN-gamma, IFN-gamma-inducing cytokines (interleukin (IL)-12 and IL-18), and IFN-gamma-inducible chemokines interferon-gamma-inducible protein of 10-kD (IP-10), monokine induced by interferon-gamma (Mig), and interferon-inducible T-cell alpha chemoattractant (I-TAC). Our results demonstrate that the concentrations of IFN-gamma, IFN-gamma-inducing cytokines, and IFN-gamma-inducible chemokines were all higher in tuberculous pleural effusions than in malignant pleural effusions. Also, IFN-gamma was significantly correlated with IL-12, Mig, and I-TAC. Moreover, receiver-operator-characteristic (ROC) analysis demonstrated that IFN-gamma produced a greater area under the ROC curve than any other factor. We conclude that the concentrations of IFN-gamma, cytokines that induced expression of IFN-gamma, and chemokines induced by IFN-gamma in tuberculous pleural effusion were all increased. The Th1 chemokines we examined, especially IP-10, are comparable to IFN-gamma as diagnostic markers of tuberculous and malignant pleural effusions, although IFN-gamma is the most valuable.