Figure 1.

Immunolabeling of PrP^Sc in the rectoanal mucosa-associated lymphoid tissues of recipient sheep transfused with different blood components. PrP^Sc immunolabeling (dark red) was visible in the RAMALT follicles of recipient sheep receiving either whole blood (A), buffy coat (B), PBMCs (C), CD72⁺ B lymphocytes (D), CD21⁺ B lymphocytes (E) or platelet-rich plasma (F) fractions but not after receiving a platelet-poor plasma (G) fraction when labeled with anti-prion mAbs. PrP^Sc immunolabeling was not observed in RAMALT follicles of scrapie negative (H) sheep or when using an isotype-matched control mAb (I; same tissue block shown in F). Scale bar = 50 μm.