CD8A and infection: In this way, MHCI presentation was achieved, and the cells were further used as APCs for the immunization of C3H/HeN mice followed by a lethal challenge with R. typhi. Immunization of the mice prior to the infection with R. typhi led to increased production of IFNγ and Granzyme B by CD8+ T cells and protected the mice from lethal outcome [190,191].