Since CD4-deficient mice are extremely susceptible to tuberculosis, it is likely that they perform a protective function, although contribution by other immune cells cannot be ruled out.68,69 Consistent with this observation, all three BCG vaccines induced robust CD62L− TEM CD4 T-cell responses in the lungs, spleens, and lymph nodes (Fig. 7e, f, g). This evidence concerns the gene CD4 and tuberculosis.