Considering the overall study population, antigen-specific IFN-γ levels detected in the QFN-G-IT and in-house QFN tubes (both containing the same antigens: ESAT-6, CFP-10 and TB7.7) was significantly higher in the Qiagen tube than in the in-house (p < 0.05) due to differences in the active TB group (Fig. 1A,C). Here, IFNG is linked to tuberculosis.