Interferon gamma mRNA quantitative real-time polymerase chain reaction for the diagnosis of latent tuberculosis: A novel interferon gamma release assay

Sunghyun Kim, Young Keun Kim, Hyejon Lee, Jang Eun Cho, Hyo Youl Kim, Young Uh, Young Mi Kim, Hyunjung Kim, Sang Nae Cho, Bo Young Jeon, Hyeyoung Lee

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The interferon gamma (IFN-γ) release assay (IGRA) is widely used as a diagnostic method for latent tuberculosis infection (LTBI). The QuantiFERON-TB Gold and QuantiFERON-TB Gold In-tube (QFT-IT) tests measure plasma IFN-γ levels using enzyme-linked immunosorbent assay (ELISA), and T-SPOT.TB counts IFN-γ-producing cells using enzyme-linked immunosorbent spot assay. IFN-γ mRNA was evaluated as an indicator of IGRA in comparison with QFT-IT IFN-γ ELISA in 46 subjects with active TB and in 73 at low risk for TB. Significant IFN-γ mRNA expression was detected from 30 min and peaked 4 h after stimulation with MTB antigens or mitogen. This was defined as the optimal time point for IFN-γ mRNA real-time polymerase chain reaction (PCR). The sensitivities of IFN-γ mRNA real-time PCR and IFN-γ ELISA were 84.8% (39/46) and 89.1% (41/46), respectively (no significant difference). Although the specificities of IFN-γ ELISA was 4.1% higher than that of IFN-γ mRNA real-time PCR (60.3% versus 56.2%), the difference was not statistically significant. The overall agreement between IFN-γ mRNA real-time PCR and IFN-γ ELISA was 79.8% (kappa = 0.475). Whilst there was no difference in the performance of IFN-γ mRNA real-time PCR and IFN-γ ELISA, IFN-γ mRNA real-time PCR was superior to IFN-γ ELISA in terms of the time required for detection of MTB infection.

Original languageEnglish
Pages (from-to)68-72
Number of pages5
JournalDiagnostic Microbiology and Infectious Disease
Issue number1
Publication statusPublished - 2013 Jan 1


All Science Journal Classification (ASJC) codes

  • Microbiology (medical)
  • Infectious Diseases

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