Dendritic cells (DC) present peripheral Ags to T cells in lymph nodes, but also influence their differentiation (tolerance/immunity, Th1/Th2). To investigate how peripheral conditions affect DC properties and might subsequently regulate T cell differentiation, we examined the effects of a potent DC-activating, TLR-4-mediated stimulus, LPS, on rat intestinal and hepatic DC in vivo. Steady-state rat intestinal and hepatic lymph DC are α E2 integrin high (CD103) and include two subsets, signal regulatory protein α (SIRPα) hi/low, probably representing murine CD8αα−/+ DC. Steady-state lamina propria DC are immature; surface MHC class II low, but steady-state lymph DC are semimature, MHC class II high, but CD80/86 low. Intravenous LPS induced rapid lamina propria DC emigration and increased lymph DC traffic without altering SIRPα high/SIRPα low proportions. CD80/86 expression on lymph or mesenteric node DC was not up-regulated after iv LPS. In contrast, iv LPS stimulated marked CD80/86 up-regulation on splenic DC. CD80/86 expression on intestinal lymph DC, however, was increased after in vitro culture with TNF-α or GM-CSF, but not with up to 5 μg/ml LPS. Steady-state SIRPα low DC localized to T cell areas of mesenteric nodes, spleen, and Peyer’s patch, whereas SIRPα high DC were excluded from these areas. Intravenous LPS stimulated rapid and abundant SIRPα high DC accumulation in T cell areas of mesenteric nodes and spleen. In striking contrast, iv LPS had no effect on DC numbers or distribution in Peyer’s patches. Our results suggest that any explanation of switching between tolerance and immunity as well as involving changes in DC activation status must also take into account differential migration of DC subsets.