TNF and infection: Based on our observations, we can assemble some key molecular events leading to immune cell apoptosis and host death after N67C infection of C57BL/6 (Supplementary Fig. S7): N67C infection results in an early death of red pulp Mɸ, NK and cDC cells in the spleen and activation of T cells that produce IFN-γ and TNF-α leading to the extensive cellular death in the spleen, lungs, BM, and possibly other tissues.