Diagnosis of active tuberculosis in China using an in-house gamma interferon enzyme-linked immunospot assay

Xinchun Chen, Qianting Yang, Mingxia Zhang, Michael Graner, Xiuyun Zhu, Nicolas Larmonier, Mingfeng Liao, Weiye Yu, Qunyi Deng, Boping Zhou

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Abstract

Gamma interferon (IFN-γ) release assays have been proven to be useful in the diagnosis of Mycobacterium tuberculosis infection. Nevertheless, their specificity and sensitivity vary among the different populations studied. Here, we evaluate the value of an in-house IFN-γ enzyme-linked immunospot (ELISPOT) assay in the diagnosis of active tuberculosis (TB) in Shenzhen, China, where the prevalence of tuberculosis is severe and Mycobacterium bovis BCG vaccination is mandatory at birth. A total of 305 patients with active tuberculosis, 18 patients with nontuberculosis lung diseases, and 202 healthy controls were recruited in this study. Among them, 156 individuals were simultaneously tested for IFN-γ responses by the commercial QuantiFERON-TB Gold in-tube (QFT-IT) assay. Tuberculin skin tests (TST) were performed with 202 healthy controls. The overall sensitivities of the ELISPOT and QFT-IT assays for active tuberculosis were 83.60% and 80.85%, respectively; the specificities were 76.6% and 73.26%, respectively. The IFN-γ ELISPOT responses, but not those of the TST, were significantly correlated with TB exposure (r = -0.6040, P < 0.0001). The sensitivities of the ELISPOT assay varied for patients with different forms of tuberculosis, with the highest sensitivity for patients with sputum-positive pulmonary tuberculosis (89.89%) and the lowest for those with tuberculous meningitis (62.5%). In conclusion, the IFN-γ ELISPOT assay is a useful adjunct to current tests for diagnosis of active TB in China. The ELISPOT assay is more accurate than TST in identifying TB infections.

Original languageEnglish (US)
Pages (from-to)879-884
Number of pages6
JournalClinical and Vaccine Immunology
Volume16
Issue number6
DOIs
StatePublished - Jun 1 2009

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ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology
  • Clinical Biochemistry
  • Microbiology (medical)

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