Development of a monoclonal antibody specific for the COOH-terminal of beta-amyloid 1-42 and its immunohistochemical reactivity in Alzheimer's disease and related disorders.

The beta-amyloid peptide (beta AP) has been characterized by protein sequencing techniques as a 39-43 amino acid protein with heterogeneous COOH-termini. Controversy exists regarding the predominant form of beta AP in neuritic plaques (NP) and cerebral vasculature of Alzheimer's disease (AD) brain. A monoclonal antibody was developed that selectively recognizes the free COOH-terminal of beta AP 1-42 but not beta AP species with shorter or longer COOH-termini. Brain sections from AD and related disorders were examined using this antibody. In AD samples, the antibody stained diffuse amyloid and NP cores, many intraneuronal and extraneuronal neurofibrillary tangles (NFT), but not cerebrovascular amyloid. Pick and Lewy bodies lacked immunoreactivity. These findings suggest that beta AP 1-42 is present in early and mature amyloid deposits and NFT, but that species of beta AP other than 1-42 comprise human vascular deposits.