Carbohydrate histochemistry of amyloid plaques in Gerstmann-Sträussler syndrome.

Prion proteins and sulfated glycosaminoglycans are known to be components of PAS-positive amyloid plaques in Creutzfeldt-Jakob disease, Gerstmann-Sträussler syndrome, and kuru. Using a panel of fluorescein labeled lectins the terminal carbohydrate residues of amyloid plaques in two patients with Gerstmann-Sträussler syndrome were investigated. Amyloid plaques in both cases had binding sites for wheat germ agglutinin, a lectin with high affinity for N-acetylglucosamine and sialic acid. Binding of other lectins was weaker and showed differences between the two cases. In situ digestion studies and dot blot experiments were performed to clarify the question if lectins preferentially bind to the carbohydrate moiety of the prion protein or to plaque-associated sulfated glycosaminoglycans. The results indicate that lectin binding is most likely attributed to the carbohydrate moiety of the prion protein rather than to glycosaminoglycans within the plaques.