Lectin histochemistry of scrapie amyloid plaques

Summary

Peroxidase-labeled lectins were used for detection of specific monosaccharide residues in amyloid plaques in brains of scrapie-infected mice. The lectins tested recognize the following residues: β-d-galactosyl (Ricinus communis agglutinin 120, RCA-1), α-d-galactosyl and α-d-galactopyranoside (Bandeirea simplicifolia aggl., BSA), α-d-mannosyl and α-d-glucosyl (Concanavalin A, Con A), N-acetylglucosaminyl and sialyl (Wheat germ aggl., WGA), sialoglycoconjugates (Limulus polyphemus aggl., LPA), α-l-fucosyl (Ulex europeus aggl., UEA-1 and Tetragonolobus aggl., TPA), N-acetyl-d-galactosaminyl (Helix pomatia aggl., HPA). The most intense staining reaction in amyloid plaques was observed with BSA and WGA; it was less intense with RCA-1, Con A, and HPA. This indicates that the plaque material contains glycoproteins with abundance of accessible residues of α- and β-galactose, N-acetyl-d-glucosamine and N-actyl-d-galactosamine, and some types of sialoglycoconjugates recognized by WGA. Such residues, like α-l-flucosyl recognized by UEA-1 and TPA, were almost undectectable in the examined plaques.

There were also some differences in the staining intensity between small and large plaques (WGA and HPA) and between central and peripheral areas of the plaques.

In the wall of micro-blood vessels relatively strong staining reaction was observed with RCA and BSA and less intense with WGA and Con A.