title: Interferon gamma mRNA quantitative real-time polymerase chain reaction for the diagnosis of latent tuberculosis: a novel interferon gamma release assay.
abstract: 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.
authors.affiliation: Department of Biomedical Laboratory Science, College of Health Sciences, Yonsei University, Wonju, South Korea.
authors.forename: Sunghyun
authors.initials: S
authors.lastname: Kim
authors.forename: Young Keun
authors.initials: YK
authors.lastname: Kim
authors.forename: Hyejon
authors.initials: H
authors.lastname: Lee
authors.forename: Jang-Eun
authors.initials: JE
authors.lastname: Cho
authors.forename: Hyo Youl
authors.initials: HY
authors.lastname: Kim
authors.forename: Young
authors.initials: Y
authors.lastname: Uh
authors.forename: Young Mi
authors.initials: YM
authors.lastname: Kim
authors.forename: Hyunjung
authors.initials: H
authors.lastname: Kim
authors.forename: Sang-Nae
authors.initials: SN
authors.lastname: Cho
authors.forename: Bo-Young
authors.initials: BY
authors.lastname: Jeon
authors.forename: Hyeyoung
authors.initials: H
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019411:Clinical Laboratory Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis* / Q000235:genetics; D059425:Interferon-gamma Release Tests / Q000379:methods*; D055985:Latent Tuberculosis / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D013997:Time Factors; D055815:Young Adult
chemical_list: D012333:RNA, Messenger; D007371:Interferon-gamma