Migrating intestinal dendritic cells transport PrPsc from the gut

Bovine spongiform encephalopathy, variant Creutzfeldt-Jakob disease (vCJD) and possibly also sheep scrapie are orally acquired transmissible spongiform encephalopathies (TSEs). TSE agents usually replicate in lymphoid tissues before they spread into the central nervous system. In mouse TSE models PrPc-expressing follicular dendritic cells (FDCs) resident in lymphoid germinal centres are essential for replication, and in their absence neuroinvasion is impaired. Disease-associated forms of PrP (PrPSc), a biochemical marker for TSE infection, also accumulate on FDCs in the lymphoid tissues of patients with vCJD and sheep with natural scrapie. TSE transport mechanisms between gut lumen and germinal centres are unknown. Migratory bone marrow-derived dendritic cells (DCs), entering the intestinal wall from blood, sample antigens from the gut lumen and carry them to mesenteric lymph nodes. Here we show that DCs acquire PrPSc in vitro, and transport intestinally administered PrPSc directly into lymphoid tissues in vivo. These studies suggest that DCs are a cellular bridge between the gut lumen and the lymphoid TSE replicative machinery.