Interleukin 27 could be useful in the diagnosis of tuberculous pleural effusions.

BACKGROUND The diagnosis of tuberculous pleural effusion (TBPE) has some limitations. We studied the efficacy of interleukin-27 (IL-27) in the diagnosis of TBPE. METHODS We measured IL-27, adenosine deaminase (ADA), ADA-2, interferon-gamma (IFNγ), and the ADA·IL-27 and ADA-2·IL-27 products in all the pleural effusion fluids. The diagnostic yield of IL-27 was evaluated with receiver operating characteristic curves. RESULTS Of 431 pleural effusions, 70 were tuberculous, 146 were neoplastic, 58 were parapneumonic, 28 were empyemas, 88 were transudates, and 41 were other types. With a cutoff point of 0.55 ng/mL, IL-27 had a sensitivity of 91.4% and a specificity of 85.1%, which were significantly less than ADA, ADA-2, IFNγ, ADA·IL-27, or ADA-2·IL-27. The area under the receiver operating characteristic curve for IL-27 (0.963) was also significantly lower than that for the other markers, except for IFNγ. However, IL-27 improved the sensitivity of ADA and ADA-2 through ADA·IL-27 and ADA-2·IL-27 products (100% for both). CONCLUSIONS IL-27 is less efficient than ADA and ADA-2 in the diagnosis of TBPE. However, ADA·IL-27 and ADA-2·IL-27 improve the diagnostic sensitivity of ADA and ADA-2, and thus could be useful in situations of high clinical suspicion and low ADA level. A value above the cutoff point of the latter is practically diagnostic of TBPE.