Direct analysis of the dynamics of the intestinal mucosa CD8 T cell response to systemic virus infection

The CD8 T cell response to vesicular stomatitis virus infection was charact erized in the spleen and intestinal mucosa using MHC tetramers, Surprisingl y, the primary response persisted in the lamina propria long after the sple nic response had declined. Furthermore, the response was characterized by a protracted effector phase in which cytolytic activity in the lamina propri a, but not in the spleen, was maintained. The appearance of Ag-specific cel ls in the intestinal mucosa was largely, though not exclusively, a result o f beta (7) integrin-mediated migration. Infection with Listeria monocytogen es or with vaccinia virus also led to sustained mucosal responses, After re infection of vesicular stomatitis virus-primed mice with a serotypically di stinct virus, a sustained recall response was detected in all tissues. In C D40(-/-) mice, the mucosal, but not the splenic, response was compromised, resulting in diminished mucosal memory. The recall response was CD40 indepe ndent and correlated with memory levels, indicating that the mucosal and sy stemic responses operated independently, These findings illustrated the int egrated yet distinct nature of systemic vs mucosal immune responses.