The clinical value of IFN-γ release assays on the diagnosis of tuberculous pleural effusion

Abstract

Objective To evaluate the clinical significance of mycobacterium tuberculosis(MTB) related interferon-gamma(IFN-γ) in vitro by enzyme-linked immunosorbent assays for the diagnosis of tuberculous pleural effusion. Methods The clinical data with fifty-five cases with tuberculous and forty-nine cases with malignant pleural effusion were diagnosed and treated in Affiliated Hospital of Jining Medical University from January to September in 2014.These patients were detected by diagnostic kit for mycobacterium tuberculosis correlative IFN-γ realse assay(TB-IGRA), bacterial smear, purified protein derivative test and mycobacterium tuberculosis antibodies.Then the above diagnostic methods were compared and analyzed.Serum carcinoembryonic antigen (CEA) and pleural fluid adenosine deaminase (ADA) together were detected, and the clinical value of TB-IGRA, CEA and ADA for differential diagnosis of tuberculous pleural effusion assessed. Results There were fifty-three TBIGRA positive cases of fifty-five patients in the tuberculosis group and the positive rate was 96.36%.However, there was only one positive case of forty-nine patients in the malignant group and the positive rate was only 2.04%.The statistical differences were significant between two groups (χ2=88.62, P<0.05). The serum CEA levels in the tuberculosis group[(2.34±1.80)μg/L] were significantly lower than the malignant group[(2358.68±1069.40)μg/L, t=-15.42, P<0.05]. The pleural fluid ADA levels [(57.51±26.90)U/L, t=11.76, P<0.05] were significantly higher than the malignant group[(14.43±3.57)U/L]. The positive rate of TB-IGRA, bacterial smear, purified protein derivative test and mycobacterium tuberculosis antibodies were 96.3%, 22.64%, 46.67% and 35.14%.The positive detection rate of TB-IGRA was highest (χ2= 78.60, P<0.05) of all.At the same time, the sensitivity(95.65%), specificity(96.77%), positive predictive value(97.78%), negative predictive value(93.75) and accuracy(92.42%) of TB-IGRA for diagnosis of tuberculous pleural effusion were highest of all. Conclusions Compared with these traditional detection indicators, TB-IGRA is more sensitive and specific.The combination of TB-IGRA with CEA and ADA detection has very important clinical value in the diagnosis of tuberculouspleural effusion. Key words: Interferon-gamma; Tuberculosis; Pleural effusion