Immunoelectron microscopy of Alzheimer and Pick brain tissue labelled with the monoclonal antibody Alz-50.

Previous studies have shown that Alzheimer and Pick brains contain abnormally elevated amounts of a 68 Kd protein detected by the monoclonal antibody Alz-50. We have used immunoperoxidase and immunological techniques to localize Alz-50-reactive epitopes in sections from Alzheimer and Pick brains at the ultrastructural level. Detectable immunoreactivity was restricted to the paired helical filaments of Alzheimer neurofibrillary tangles and to the paired helical and straight filaments of Pick bodies. In Alzheimer tissue, the antibody also labelled scattered neuronal paired helical filaments that were not aggregated into neurofibrillary tangles. Amorphous components of Pick bodies and other constituents in the Alzheimer and Pick brain tissue were not immunostained.