Organ-specific regulation of the CD8 T cell response to Listeria monocytogenes infection

The intestinal mucosal CD8 T cell response to infection with Listeria monoc ytogenes tvas measured using MHC class I tetramers and was compared with th e response in peripheral blood, secondary lymphoid tissue, and liver. To as sess the vaccination potential of Listeria and to analyze responses in C57B L/6 mouse strains, a recombinant Listeria expressing OVA (rLM-ova) was gene rated. The response peaked at 9 days postinfection with a much larger fract ion of the intestinal mucosa and liver CD8 T fell pool OVA specific, as com pared with the spleen. However, these differences were not linked to bacter ial titers in each site. The higher responses in lamina propria and liver r esulted in a larger CD8 memory population in these tissues. Furthermore, th e level of memory induced mas dependent on infectious dose and inversely co rrelated with the magnitude of the recall response after oral challenge, Re call responses in the tissues were most robust in the lamina propria and li ver, and reactivated Ag-specific T cells produced IFN-gamma, Infection of C D40- or MHC class II-deficient mice induced poor CD8 T cell responses in th e intestinal mucosa, but only partially reduced responses in the spleen and liver. Overall, the results point to novel pathways of tissue specific reg ulation of primary and memory antimicrobial CD8 T cell responses.