Influence of previous tuberculin skin test on serial IFN-γ release assays.

Ilaria Sauzullo (1) , Anna P Massetti (1) , Fabio Mengoni (1) , Raffaella Rossi (1) , Miriam Lichtner (1) , Camilla Ajassa (1) , Vincenzo Vullo (1) , Claudio M Mastroianni (1)

1 Department of Public Health and Infectious Diseases

Tuberculin skin test (TST) and interferon-γ release assays (IGRAs) have been proposed for serial testing in tuberculosis. In the present study, we assessed the effect of TST on subsequent QuantiFERON-TB Gold In-Tube (QFT-GIT) results by monitoring the evolution of responses during a follow-up period of 6 weeks. One hundred and two subjects were initially tested with QFT-GIT and subsequently with TST; then the QFT-GIT was performed serially 1, 2, 4, and 6 weeks after the TST. A subgroup of 40 subjects was also assessed by older version of the QuantiFERON-TB Gold (QFT-G) assay. The results showed no significant variation in IFN-γ response over time in the tested patients, although two TST-positive subjects showed evidence of possible boosting effect. In addition, a direct comparison between the QFT-G and QFT-GIT test showed no significant differences at any time point with excellent agreement between two tests. No significant differences were seen in IFN-γ responses between BCG-unvaccinated and BCG-vaccinated patients at each time point. In conclusion, our findings indicate that TST does not influence the outcome of subsequent IGRAs testing in individuals with negative TST results, but it can boost the IFN-γ response in subjects sensitized to TB antigens and not detected by IGRA.

Domaines: Microbiologie et Parasitologie; Santé publique et épidémiologie

Ilaria Sauzullo, Anna P Massetti, Fabio Mengoni, Raffaella Rossi, Miriam Lichtner, et al.. Influence of previous tuberculin skin test on serial IFN-γ release assays.. Tuberculosis, 2011, 91 (4), pp.322-6. ⟨10.1016/j.tube.2011.05.004⟩. ⟨pasteur-00976750⟩