[Ultrastructural and immunohistochemical study of the olfactory mucosa in Alzheimer's disease].

The discovery of reliable peripheral markers would be of great interest for the diagnosis of Alzheimer's disease. Interestingly specific lesions of Alzheimer's disease were found in the olfactory areas of the brain. The loss of the detection and the identification capabilities in olfaction suggest a defect in the olfactory mucosa. The ultrastructural study of biopsy of olfactory mucosa from patients suspected to suffer of Alzheimer's disease revealed a degeneration of sustentacullar and olfactory cells as well as an architectural disorganization. No neuropathological characteristic lesion such as Paired Helicoidal Filaments or amyloid fibrils could be evidenced. Immunohistochemical analysis achieved with a polyclonal antiserum raised against A4 protein (fragment 1-28) showed a specific staining in the sustencellular and of the outer part of the olfactory epithelium corresponding to the mucus area, whereas appropriate controls were negative. Our study raised the question of the amyloid protein origin in the olfactory mucosa. Analysis of some more patients will enable us to determine the diagnostic value of this study in Alzheimer's disease.