IFNG and tuberculosis: Among those with active TB, there was a significant difference by χ2 for the trend among the categories of the CD4+ T-cell counts in the proportion of responders to the IFN-γ based experimental test (p = 0.03), IP-10-based experimental test (p = 0.048) and for the IFN-γ-response to the TB antigen of the QFT-IT.