Abstract: Objective   To evaluate the value of interferongamma release assay(IGRA) in diagnosis of tuberculosis. Methods   The study recruited  130 cases of active tuberculosis  clinically proved from Beijing Chest Hospital， and 89 cases of old healed tuberculosis and 137 cases of nonTB patients from Beijing Haidian Hospital. TSPOT.TB test and fluorescence staining before antituberculosis therapy were performed in all patients．According to the result of the fluorescence staining， the patients with tuberculosis were divided into positive group and negative group. According to the age， the patients were divided into younger  group and elderly group. The diagnostic performance of  TSPOT.TB was compared.Results   The sensitivity of the tuberculosis from TSPOT.TB diagnosis was 82.307％， the specificity was 75.182％. The positive rates of TSPOT.TB among pulmonary tuberculosis， old healed tuberculosis and nonTB patients were significantly different (χ2=7.580，P=0.032). The positive rate of TSPOT.TB in old healed tuberculosis was significantly higher than that of nonTB patients. The sensitivity of pulmonary tuberculosis was 86.60％， the specificity of TSPOT.TB was 75.0%， the sensitivity of the fluorescence staining was 65.17％， the specificity of the fluorescence staining was 98.33%. The comparison between the two results had remarkable statistical significance（P<0.001）. The sensitivity of the younger group was obviously higher than that of the elder group (χ2=4.782，P=0.029). Conclusion   TSPOT.TB is more quick and convenient. It also has a higher sensitivity and negative predicted value. TSPOT.TB is a more valuable auxiliary diagnosis to younger patients. It can be used in the diagnosis of smear negative pulmonary tuberculosis patients and is not recommended in identifying old healed tuberculosis and active tuberculosis.

Key words: tuberculosis, pulmonary； interferongamma； enzymelinked immunospot assay