Filamentous arrays reminiscent of tropomyosin crystals in Hirano bodies of Alzheimer's disease

Abstract

Distinctive acidophilic rods, Hirano bodies, have been observed in brains of patients under a variety of pathological conditions, including Alzheimer's disease, and also in normal, aged individuals. Data on the three-dimensional conformation and on the chemical composition of these structures are presently controversial. The presence of actin in Hirano bodies has been indicated immunocy tochemically. Other authors have proposed that Hirano bodies are crystalline arrays of ribosomes attached to membranes. We report here the results of an investigation of Hirano bodies in the brains of Alzheimer's patients. Applying the techniques of three-dimensional electron microscopy, we have demonstrated as a major component of the Hirano bodies, characteristic arrays of filamentous proteins reminiscent of tropomyosin crystals produced in vitro.Frontal lobe biopsies from 3 patients with pre-senile dementia diagnosed as Alzheimer's disease were investigated by three-dimensional electron microscopy. Fig. 1 is a survey of a Hirano body occupying the main portion of a neurite. It is comprised of sheets of filaments forming characteristic network patterns.