The expression of prion protein (PrP(C)) in the megakaryocyte lineage.

Summary. Background: Cellular prion protein (PrPC) is a naturally occurring protein in normal individuals which adopts an abnormal conformation, termed scrapie prion protein (PrPSc) that is associated with disease. There is great concern that clinically asymptomatic variant Creutzfeldt–Jacob disease (vCJD) may transmit PrPSc in blood transfusion products. PrPC is widely expressed and has been found in human blood. The majority of cellular borne PrPC is associated with platelets (84%). Although PrPC mRNA has been demonstrated in platelets, the quantity is unknown and may not reflect the total PrPC present. Objective: To investigate the expression of PrPC in the megakaryocyte lineage. Methods: The expression of PrPC was studied in CD34+ cells, cultured megakaryocytes and platelets using electron microscopy, flow cytometry, semi-quantitative RT-PCR and immunofluorescence confocal microscopy. Results and conclusions: The expression of PrPC appeared to increase with differentiation and polyploidization in the megakaryocyte lineage. PrPC was located within platelet α-granules and its source is likely to be from megakaryocyte precursors. If PrPSc has a similar distribution, these results have implications for the selection of blood donors and preparation of cell-depleted blood products.