Abstract: Objective To evaluate the clinical application value of Mycobacterium tuberculosis T cell enzyme-linked immunospot tuberculous test (T-SPOT.TB test) in the diagnosis and differential diagnosis of tuberculous pleurisy. Methods Ninety-three patients with pleural effusion who were hospitalized in Shenyang Chest Hospital from August 2012 to June 2013 were enrolled in this study. According to the diagnostic criteria of tuberculous pleurisy in clinical guidelines for the diagnosis and treatment of tuberculosis, 48 patients with tuberculous pleurisy and 45 cases of non-tuberculous pleurisy were divided into study group and control group. The number of T lymphocytes (namely spots forming cells, SFC) to early secretary antigenic target 6 (ESAT-6) and/or culture filtrate protein (CFP-10) sensitive in peripheral blood mononuclear cell (PBMC) of participants were determined by T-SPOT.TB test. The positive rates of SFC in two groups were compared. The results were compared with other related indicators (adenosine deaminase (ADA), serum tuberculosis antibody (TB-AB), and tuberculosis bacterium culture (Mtb culture) of pleural effusion. SPSS 17.0 was used for statistical analysis. Pearson Chi-square test was used to compare rates and P value less than 0.05 was considered statistically significant. Results The positive rate of tuberculous pleurisy group (91.67%, 44/48) by T-SPOT.TB test was significantly higher than that of control group (8.89%, 4/45). The difference χ² was statistically significant (χ²=63.73, P<0.05). The sensitivity of T-SPOT.TB test in detection of ESAT-6 and CFP-10 (91.67%, 44/48) was higher than that in detection of ESAT-6 (85.42%, 41/48) or CFP-10 (75.00%, 36/48). The difference had no statistical significance (compared with ESAT-6, χ²=0.92, P>0.05; compared with CFP-10, χ²=4.8, P>0.05). The sensitivities of T-SPOT.TB, ADA detection, TB-AB detection and Mtb culture were 91.67% (44/48), 70.83% (34/48), 62.50% (30/48) and 14.58% (7/48) respectively. The specificities were 91.11% (41/45), 55.56% (25/45), 62.22% (28/45) and 100.00% (45/45). The diagnostic accuracy rates were 94.62% (88/93), 63.44% (59/93), 62.37% (58/93) and 55.91% (52/93). Except the specificity of Mtb culture which was higher than T-SPOT.TB test, the sensitivity and specificity of T-SPOT.TB test were higher than those of other test methods, and the difference was statistically significant (compared with ADA-sensitivity χ²=6.84, P<0.05, specificity χ²=14.55, P<0.05; compared with TB-AB-sensitivity χ²=11.56, P<0.05, specificity χ²=10.49, P<0.05; compared with Mtb culture-specificity χ²=57.27, P<0.05, specificity χ²=4.18，P<0.05).  Conclusion T-SPOT.TB test has high sensitivity, specificity and diagnostic accuracy in the diagnosis of tuberculous pleurisy. Therefore, it is worth in the clinical extension and application.

Key words: Tuberculosis, pleural, Interferon-gamma release tests, Sensitivity and specificity