Properties of antigenic determinants that distinguish neurofibrillary tangles in progressive supranuclear palsy and Alzheimer's disease

Neurofibrillary tangles (NFT) in Alzheimer's disease (AD) and in progressive supranuclear palsy (PSP) differ in their location and morphology, but both appear to express the same or similar epitopes. These immunologic data may signify that both types of NFTs contain the same components and arise as a result of the same mechanisms. To explore this hypothesis, we probed PSP and AD samples of brain stem, where both PSP and AD NFTs occur, using a large panel of monoclonal antibodies (MAbs). The epitopes expressed in brain stem PSP and AD NFTs were compared with those in the NFTs of AD hippocampus. NFTs in PSP hippocampus were too infrequent for comparative analysis. The MAbs were raised to neurofilament and tau proteins, or to AD paired helical filaments. All MAbs raised to tau (three) and paired helical filaments (two) recognized brain stem PSP NFTs and AD NFTs in brain stem and hippocampus. However, 12 anti-NF MAbs specific for multiphosphorylation repeat domains or other phosphate-dependent and independent epitopes did not bind PSP NFTs, but they did detect AD NFTs in hippocampus, and 5 of these MAbs also recognized brain stem AD NFTs. We conclude that some populations of AD NFTs contain antigenic determinants that are not found in PSP NFTs. This may reflect the effect of different pathologic events specific to PSP and AD, or the selective formation of NFTs in different groups of neurons in each of these disorders.