TNF and infection: TNF is a molecule that does 4 key things in TB immunobiology, and thus in our models: (1) TNF acts to enhance recruitment of immune cells during infections, (2) TNF activates macrophages that make chemokines, (3) TNF allows for bacterial killing by macrophages, upon activation, and (4) TNF itself can induce death (apoptosis) of infected cells also killing intracellular bacteria.