CD4 and tuberculosis: Regarding the response to the TB Antigen of the QFT-IT format, we found that the sensitivity of IP-10 for detecting active TB was similar to what was reported for the QFT-IT response (evaluated by definition by IFN-γ).However, differently from QFT-IT, the IP-10-mediated response was not dependent on the CD4+ T-cell counts and IFN-γ mitogen response.