In
neurodegenerative disorders, hyperphosphorylated
tau proteins aggregate into abnormal filaments. In the present study,
tau protein alterations were studied in one
corticobasal degeneration and seven
Pick's disease cases using specific immunological probes. The typical lesions of
corticobasal degeneration and
Pick's disease were revealed by immunohistochemistry, including the presence of Pick bodies and achromatic swollen neurons, neuritic alterations, and neurofibrillary tangles. Tau-immunoreactive glial tangles were also observed. By immunoblotting, the case of
corticobasal degeneration was characterized by the tau profile previously reported to occur in
progressive supranuclear palsy with an intense labeling of the two tau 64 and 69 bands, while tau 55 was not visualized. In
Pick's disease cases with Pick bodies and neurofibrillary tangles, a tau triplet similar to that encountered in
Alzheimer's disease (tau 55, 64 and 69) was detected. Furthermore, a particular tau profile was found in four
Pick's disease cases showing only Pick bodies and no neurofibrillary tangles. In these cases, tau 55 and 64 were strongly immunoreactive, whereas tau 69 was almost unlabeled. These differences are likely to be related to particular pools of tau
isoforms present within the degenerating neurons. Since there is a great diversity of
neurodegenerative disorders with substantial clinical and neuropathological overlap, the electrophoretic profile of
tau proteins could represent a useful marker for the type of neurodegeneration.