Migration of dendritic cells into the brain in a mouse model of prion disease.

The immune system plays a key role in the dissemination of prion infections from the periphery to the central nervous system (CNS). While follicular dendritic cells are critical for prion replication in lymphoid tissue and subsequent neuroinvasion, myeloid dendritic cells (DCs) have been implicated in both the clearance and propagation of pathological prion protein. Since nothing is known on the ability of DCs to migrate to the CNS during prion diseases, we investigated the immunohistochemical localization of CD205(+) DCs in the brain of C57BL/6 mice intraperitoneally infected with the mouse-adapted KFu strain of Gerstmann-Sträussler-Scheinker syndrome, a human genetic prion disorder. In normal brain, CD205(+) cells were present in the meninges and choroid plexus, whereas in the majority of mice sacrificed between 120 and 300 days post infection, CD205(+) DCs were also detected in the cerebral cortex, subcortical white matter, thalamus and medulla oblongata. These findings demonstrate that DCs can enter the CNS of prion-infected mice, suggesting a possible role for these cells in the pathogenesis of prion disorders.