Value of interferon-γ release assay of pleural effusion in the diagnosis of tuberculous pleuritis

Objective To explore the value of interferon-γ (IFN-γ) release assay (IGRA) of pleural effusion in the diagnosis of tuberculous pleuritis.Methods Between November 2009 and January 2012,62 patients with pathologically confirmed diagnosis of tuberculous pleuritis and 30 with miscellaneous diseases (i.e.tumor and inflammatory pleuritis) from the Department of Respiratory Internal Medicine,Henan Provincial Chest Hospital were enrolled in the study.The pleural effusion was sampled 2 weeks prior to the treatment.IFN-γ concentration was measured by enzyme-linked immunosorbent assay following stimulation with early secretory antigen target-6 (EAST-6) for Mycobacterium tuberculosis.Results Positire rate of IGRA was 90.3％ (56/62) in tuberculous pleuritis patients,with an increase by 16％-53％ in IFN-γ production.Though patients with non-tuberculous pleuritis yielded a 6％-8％ increment in IFN-γ release following EAST-6 stimulation,30 cases tested negatively to IGRA with exception of 2 with borderline positive results.Pleuralfluid of tuberculous pleuritis patients was characterized by a higher level of IFN-γ than that of other patients [(1825 ± 69)ng/L vs (967 ± 105)ng/L,P＜0.05].Conclusion Pleural fluid IGRA is a potentially accurate and reliable approach for differential diagnosis of tuberculous pleuritis. Key words: Tuberculosis, pleural;  Interferon-γ release assay;  Hydrothorax;  Diagnosis