Dendritic cell immunization route determines integrin expression and lymphoid and nonlymphoid tissue distribution of CD8 T cells

Exogenous dendritic cells (bone marrow-derived dendritic cell (BMDC)) display restricted trafficking in vivo after injection into mice, but the route(s) by which they generate gut-homing effector cells is unclear. Mesenteric lymph nodes (LN) and spleen were differentially targeted by i.p. and i.v. administration of BMDC, respectively, whereas mediastinal LN were targeted by both routes. BMDC injected by either route activated CD8⁺ T cells to lip-regulate both α⁴β¹ and α ₄β₇ integrals. However, the lymphoid compartment in which activation occurred determined their expression kinetics, magnitude, and population distribution. Only T cells activated in mesenteric LN after i.p. immunization expressed high levels of α₄β₇, which also correlated with localization to small intestine. These α₄β₇^high cells also redistributed to mediastinal LN in a manner sensitive to treatment with α ₄β₇ blocking Abs, but not to mucosal addressin cell adhesion molecule-1 blocking Abs. Our results demonstrate the importance of lymphoid compartment, as dictated by immunization route, in determining integrin expression on activated T cells and their distribution in lymphoid and nonlymphoid tissues.