Cellular localisation of PrPC in alpha cells of human pancreases based on immunofluorescence analysis. (a)–j) We found no co-registration of PrPC with glucagon in either non-diabetic or type 1 diabetic INS(+) islets (k)–o) but did find co-localisation of PrPC with insulin (white arrowheads e and j). PrPC was found to be co-localised with alpha cells in type 1 diabetic INS(−) islets, suggesting that PrPC expression is activated in alpha cells in the absence of beta cells in these islets. Co-registration was confirmed using z-stack 3D image reconstruction analysis shown in (n). Scale bars, 20 μm. GCG, glucagon; INS, insulin; ND, non-diabetic, T1D, type 1 diabetic