Mycobacterium tuberculosis infection: signification, role and performance of mesure of cell-mediated immune response The tuberculin skin test (TST) and IGRAs are to date the unique way to identify individuals latently infected with Mycobacterium tuberculosis. In contrast to IGRAs, test specificity of TST is clearly affected by prior vaccination with attenuated strain M. bovis (BCG). Moreover, there is evidence suggesting that the accuracy of IGRAs is higher than that of TST and therefore IGRAs should perform better to detect latent tuberculosis in immunosuppressed individuals. However, neither TST nor IGRAs permit to discriminate between latent and active infection. Furthermore, there is no available test capable to identify whether individual with latent infection harbor live or dead mycobacteria and thus to detect who is at risk to develop active tuberculosis.