Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSE) that affects members of the Cervidae family, including deer (Odocoileus spp.), elk (Cervus Canadensis spp.), and moose (Alces alces spp.). While CWD is a neurodegenerative disease, lymphoid accumulation of the abnormal isoform of the prion protein (PrPSc) is detectable early in the course of infection. It has been shown that a large portion of the PrPSc lymphoid accumulation in infected mule deer takes place on the surface of follicular dendritic cells (FDCs). In mice, FDC expression of PrPC has been shown to be essential for PrPSc accumulation. FDCs have been shown to normally express high levels of PrPC in mice and humans but this has not been examined in natural hosts for CWD. We used double immunofluorescent labeling and confocal microscopy to determine the PrPC expression characteristics of B and T lymphocytes as well as FDCs in palatine tonsils of CWD-negative mule deer and elk. We detected substantial PrPC colocalization with all cellular phenotypic markers used in this study, not just with FDC phenotypic markers
