Diagnostic value of an IFN-γ ELISPOT assay to detect latent tuberculosis infection in hepatitis C patients

Abstract

The rapid diagnosis of tuberculosis (TB) and latent tuberculosis infections (LTBI) is a significant problem in clinical practice. The aim of this study was to evaluate the diagnostic value of an enzyme-linked immunosorbent spot (ELISPOT) assay measuring interferon-γ in hepatitis C patients with LTBI. A total of 160 hepatitis C patients at the Jilin University Hospital, Changchun, China, were prospectively enrolled from January 2009 to December 2010; 43 had been positively diagnosed with TB, 38 with non-TB diseases, and 79 with a history of TB. All patients were evaluated by the tuberculin skin test (TST) and ELISPOT assays. Among the 43 diagnosed TB patients, the ELISPOT assay had a sensitivity of 92.1%, compared to a sensitivity of 60.5% for the TST. Among the 79 TB exposure patients, the ELISPOT assay was more sensitive (90%) than the TST (61.5%), the specificity of the ELISPOT assay was 90%, and the specificity of the TST was 61.5% in LTBI. Among the 38 subjects with non-TB diseases, the specificity of the ELISPOT was better than the TST’s. In conclusion, this ELISPOT assay could provide useful support in diagnosing LTBI in hepatitis C patients and may provide guidance regarding the treatment of LTBI and hepatitis C co-infection. Key words: Latent tuberculosis infections (LTBI), Hepatitis C virus (HCV), enzyme-linked immunosorbent spot (ELISPOT) assay, CFP-10/ESAT-6