Expression of cellular prion protein on blood cells: potential functions in cell physiology and pathophysiology of transmissible spongiform encephalopathy diseases.

The cellular prion protein (PrPc) holds a central role in the pathophysiology of transmissible spongiform encephalopathies (TSE). The hallmark of these progressive neurodegenerative diseases is the accumulation of the protease-resistant, pathologic conformation of prion protein (PrPres) in the CNS. The conformational change is thought to be propagated by a template-like effect in which a normal prion protein (PrPc) interacts with its PrPres isoform and assumes the pathologic conformation. In its natural conformation, the prion protein is expressed on many different cell types, but its physiological function has yet to be clearly defined. PrPc expressed on blood cells or present in plasma may contribute to the transport of TSE infectivity found in blood of infected animal models. We examine the expression of PrPc on human and animal blood cells and its potential functional roles and discuss studies of transfusion-mediated transmission of TSE infectivity in animals.