The effect of antituberculosis treatment on interferon-γ release assay results

Background and Aim. Monitoring the efficacy of antituberculosis therapy is crucial. The aim of this work is to investigate the effect of tuberculosis treatment on interferon- γ response using Quanti-FERON©-TB Gold in tube (QFT-GIT). Methods. A total of 216 new pulmonary tuberculosis (TB) cases were tested with QFT-GIT at the start of the treatment and, randomly, once or twice between 90 and 180 days afterwards. Data was analysed using the random effect regression model analysis. Results. 63.4% of patients were positive at the QFTGIT (>.35 UI cut-off). TB cases showed a significant loglinear increase in interferon-γ (IFN-γ) concentration, over time of treatment: IFN-γ concentration increased by 78% after 6 months of treatment in acid-fast bacilli positive (A) and culture negative cases in culture confirmed cases the increase was 43% if A+ and 20% in A-. Conclusions. Effective therapy seems to restore cellular responses to Mycobacterium tuberculosis antigens. The potential use of interferon gamma release assay (IGRA) in monitoring response to TB treatment is hampered by the presence of active mycobacterial replication at baseline and needs further evaluation.