Immunoreactivity of cerebral amyloidosis is enhanced by protein denaturation treatments

We investigated paraffin-embedded brain sections from three patients with Gerstmann-Sträussler syndrome and three patients with Alzheimer's disease or senile dementia of Alzheimer type using anti-human prion protein antisera and anti-β/A4 protein antisera after protein denaturation treatments. After incubation with guanidine-thiocyanate, trichloroacetate, and phenol, the immunoreactivity of kuru plaques and senile plaques was enhanced to the same level as the formic acid treatment. These treatments revealed small compact amyloid deposits, amyloid deposits surrounding the plaque cores, and diffuse plaques. Most of these chemicals changed the congophilia of both amyloids. It is possible that these treatments denature amyloid fibril proteins and break down the structure of amyloid fibrils, thus revealing buried epitopes.