Human olfactory epithelium in normal aging, alzheimer's disease, and other neurodegenerative disorders

By use of immunohistochemistry, we characterized the molecular phenotype of human olfactory epithelial (OE) cells and assessed the nature of the dystrophic olfactory neurites described initially in Alzheimer's disease (AD). Keratin 8 was present in all classes of OE cells. Sustentacular cells lacked other cell type specific polypeptides and were distinguished from neurons and basal cells because the latter two classes of OE cells expressed neural cell adhesion molecules (N‐CAMs) and microtubule associated proteins (MAPs), i.e., MAP5. Basal cells expressed nerve growth factor receptors (NGFRs), which distinguished them from olfactory neurons. Unlike their perikarya, olfactory axons expressed vimentin and GAP‐43, but not peripherin or neurofilament (NF) proteins. Olfactory nerves were distinguished from other axons because the latter were positive for all three NF subunits and peripherin, in addition to vimentin and GAP‐43.