Amyloid beta protein 1-42/43 (A beta 1-42/43) in cerebellar diffuse plaques: enzyme-linked immunosorbent assay and immunocytochemical study.

Diffuse plaques are immature and amorphous senile plaques and believed to be in the initial phase of plaque formation. In contrast to amyloid angiopathy and the plaque core amyloid, diffuse plaques failed to be purified in preserved forms from the brain. Here, we studied the diffuse plaques in the cerebellar region of the Alzheimer's disease brain based on immunocytochemistry and ELISA using two different monoclonal antibodies specifically recognizing the carboxyl termini of A beta molecules (BA27 for A beta 1-40 and BC05 for A beta 1-42/43). We found that the amount of A beta 1-40 was in proportion to the staining degree on amyloid angiopathy by immunohistochemistry. We found that A beta 1-42/43 comprised diffuse plaques as the major component in the cerebella of AD brains. Taking these findings into consideration, diffuse plaques, the earliest pathological change in the brain with AD, are concluded to be composed mainly of A beta 1-42/43, implicating the critical importance of this kind of A beta species deposition in the pathogenesis of AD.