To achieve this, we used a TCR‐KO adoptive transfer model of M.tb infection (i.e., TB‐TKO), and evaluated the subpopulations of CD4+ T cells that developed in mice at 30 and 60 days post‐infection, after receiving naive CD4+ T cells from old mice with (test group; OM‐TB‐TKO) or without (old control; O‐TB‐TKO) mito‐transfer [Figures 3 (lung) and 4 (spleen)]. The gene discussed is CD4; the disease is tuberculosis.