The magnitude of the Mycobacterium (M.)tuberculosis antigen-specific interferon gamma (IFN-g) T-cell response to infecting M. tuberculosis is hypothesized to be proportional to the antigenic load of the infecting organism in human and animal models.[5], [6] We have shown that the quantitative response, as measured by ELISPOT, correlates with exposure to a TB case, reflecting the infectious load of M. tuberculosis. Here, IFNG is linked to tuberculosis.