CD4 and infection: Half of these cells are CD69+ (Kornfeld et al., 1999; Refai et al., 2018; Chen et al., 2022), indicating that activated T cells migrate to the site of infection, interact with M.tb-infected macrophages and DCs through CD40L on CD4+ T cells and CD40 on macrophages or dendritic cells (Kalams and Walker, 1998; Clarke, 2000).