Establishment of a monoclonal antibody against senile plaques and its application for immunohistological and immunoelectron microscopical studies in the brain of the elderly.

A monoclonal antibody (Am-3) was produced against senile plaques in the brain of a patient with Alzheimer's disease. Am-3 was reactive with senile plaques of typical, primitive and diffuse type not only in the brain used as immunogen, but also those in the brain of 15 out of 25 autopsy cases of the aged people. Moreover, Am-3 was also reactive with granular materials of various sizes scattered in the 1st, 3rd and 4th layers of the cerebral cortices of the cases with severe dementia. Am-3 was also reactive with vessel wall of the congophilic angiopathy. By immunoelectron microscopic examination, Am-3 was positive with amyloid fibril in the core and crown of senile plaques, and in the congophilic angiopathy.