Topo-optical visualization reactions of carbohydrate-containing amyloid deposits in the respiratory tract

Staining with Congo red according to is the most commonly used method for the demonstration of amyloid, but structures other than amyloid can give false-positive results. To overcome this problem, introduced an aqueous Congo red staining with gum arabic as the mounting medium, which we have used in this and previous publications. Most histochemical studies on amyloid deposits to date have concentrated on conventional methods including staining with thioflavine, sirius red, alcian blue, methyl and crystal violet. In this study, we used topo-optical reactions with thiazine dyes on both the light and polarization microscopic level to establish the structure, distribution and location of carbohydrate components that occur within amyloid deposits, especially in the respiratory tract. Topo-optical staining reactions for the qualitative analysis of carbohydrate components in amyloid deposits included (1) reactions that identify the carbohydrate residues, (2) reactions that detect sialic acids and, (3) methods that visualize glycosaminoglycans. In conclusion, a comparison of consecutive serial sections stained with Congo red, aldehyde bisulfite toluidine blue reaction, sialic acid-specific topo-optical reaction, toluidine blue topo-optical reaction and chemically intensified basophilic reaction showed correlative staining patterns and anisotropic effects, corresponding to a close pathomorphological relationship between amyloid fibrils, periodate reactive carbohydrates, including sialic acids, and glycosaminoglycans.