The lack of dependence on cathepsin B or caspase-1, together with the unique ultrastructural features, lack of dependence on Bax or Bak, and the previously reported lack of dependence on executioner caspases, TNF-α, Toll signals and free radicals of oxygen or nitrogen [5] demonstrate that the macrophage cell death mode induced by virulent Mtb is unlike any previously reported infection-induced cell death. This evidence concerns the gene TLR4 and infection.