Characterization of early transient accumulation of PrP(Sc) in immune cells

PrP(Sc) is known to elicit no specific immune response and the immune cells are suspected to support its accumulation. In the present study, we investigated the response of some immune cell types to PrP(Sc) to characterize an observed early transient accumulation of PrP(Sc). After cells were treated with PrP(Sc)-brain homogenate, PrP(Sc) was transiently accumulated for the first 8-12h post-exposure then completely cleared by the 5th day of the experiment. The accumulated PrP(Sc) was not a de novo product of the cell PrP(C). Further investigation of this phenomenon revealed some potential factors influencing it. These factors included cholesterol homeostasis, temperature, the degradation power of the cell and the availability of sufficient PrP(C). Our in vitro results suggest that immune cells, especially macrophages are potential risk factors for the accumulation and intercellular spread of PrP(Sc) if the complete clearance of PrP(Sc) were not fulfilled.