Role of QuantiFERON-TB Gold antigen-specific IL-1β in diagnosis of active tuberculosis

The main objective of the study was to evaluate whether in vitro QuantiFERON-TB Gold In-Tube (QFT-GIT) assay antigen-specific IL-1 beta, TNF-alpha, IL-2, IL-6, IL-8 and IL-12 (p40) production is associated with active TB. In a cohort of 77 pulmonary TB patients (PTB), 67 healthy household contacts (HHC) and 83 healthy control subjects (HCS), the antigen-specific cytokines levels were determined in supernatants generated from QFT-GIT tubes. Antigen-specific IL-1 beta levels were significantly higher in PTB than HHC and HCS. At a fixed cutoff point (1,108 pg/ml), IL-1 beta showed positivity of 62.33 % in PTB, 22.38 % in HHC and 22.89 % in HCS. Moreover, antigen-specific IL-1 beta assay can differentiate PTB and HHC (believed to be latently infected) (p < 0.0001). Like IL-1 beta, significantly higher levels of antigen-specific TNF-alpha were associated with PTB and displayed 43.63 % positivity in PTB. The antigen-specific IL-2 levels were associated both with PTB (54.54 %) and HHC (48.14 %). Other cytokines levels did not differ among the groups. Our results suggest that antigen-specific IL-1 beta can be used as a biomarker for active TB diagnosis as well as for differential diagnosis of PTB and LTBI.