Abstract: Objective  To evaluate the value of diagnosis for active pulmonary tuberculosis with blood interferon gamma release assay stimulated by three antigens of PPD, ESAT-6/CFP-10 fusion protein(E/C) and ESAT-6.  Methods  187 participants including patients with active pulmonary tuberculosis and control were enrolled. 5 ml morning fasting venous heparinazed blood were taken from all participants and stimulated by purified protein derivative(PPD), early secretory antigenic target 6(ESAT-6) and E/C. The production of IFN-γ was measured by ELISA after incubated for 16-22 hours. Results  The production of IFN-γ stimulated by ESAT-6, E/C and PPD in active pulmonary tuberculosis was 96(41-379), 3180(1192-7231) and 4348(1230-9026) pg/ml, respectively. It was much higher than that in control （ESAT-6：10（4-52）、E/C： 210（49-523）、PPD： 1800（70-3021），U=1190.5、2405和1309.5，P<0.01）. The sensitivity and specificity of ESAT-6, E/C and PPD were 78.1%(75/96) vs 76.9%(70/91)、87.5%(84/96) vs 83.5%(76/91) and 85.4%(82/96) vs 65.9%(60/91), respectively. Conclusion  The ESAT-6/CFP-10 fusion protein could be a very useful supplementary tool for the diagnosis of active pulmonary tuberculosis.

Key words: Tuberculosis, pulmonary/diagnosis, Recombinant fusion proteins, Enzyme-linked immunosorbent assay, Interferon-gamma release tests