Abstract: Objective To evaluate the clinical application of the whole blood interferon γ (IFN-γ) release assay of QuantiFERON TB Gold in tube (QFT-GIT) in diagnosis of tuberculosis. Methods From October 2014 to October 2015, 109 patients with tuberculosis (45 cases of confirmed patients and 64 cases of clinically diagnosed patients) and 70 patients with non-tuberculosis were enrolled in Tianjin Medical University General Hospital. In order to evaluate diagnosis value between two kinds of tests, and to compare the differences between two groups, QFT- GIT test and colloidal gold anti tuberculosis antibody (TB-Ab) were employed to detect in two groups of patients. The ROC curve of IFN-γ release quantity was analyzed in two groups. Results The sensitivity and specificity of QFT-GIT were 93.58% and 85.71% respectively. The positive rate was significantly higher in QFT-GIT than that of TB-Ab (χ2=43.68， P＜ 0.01). The sensitivity of combined detection of the two methods decreased to 52.3% (57/109), but the specificity increased to 90.0% (63/70). The release quantity of IFN-γ was significantly higher in tuberculosis group than that in the non-tuberculosis group (U=330， P<0.05). The area under the ROC curve of IFN-γ release quantity was 0.913 (95%CI: 0.864-0.963). Conclusion The whole blood IFN-γ release assay of QFT-GIT is a sensitive and specific assay for detecting tuberculosis infection. The combination QFTGIT with TB-Ab can improve the specificity further, which could be a useful tool for the diagnosis of tuberculosis ．

Key words: tuberculosis, BCG vaccine, diagnostic tests, routine, sensitivity and specificity, ROC curve, interferon- &gamma, release assay, TB-Ab