Distribution of Alzheimer's disease amyloid protein precursor in normal human and rat nervous system.

Alzheimer's disease and cerebral amyloid angiopathies (CAA) are clinically heterogeneous diseases, but pathogenically related by the deposition of beta A4-amyloid in the brain in the form of neuritic plaques and/or vascular infiltrates. Antibodies directed against the N-terminal region of the predicted sequence of the beta A4 amyloid protein precursor (APP) were used to investigate the cellular distribution of this protein in the brain of normal humans and rats. We found a widespread presence of APP throughout the nervous tissue, including neurons, blood vessels, meningeal membranes, choroid plexus and ependymal cells. The highest APP immunoreactivity in both species was found in neuronal cell bodies and their processes, and around blood vessels. These findings may account for the clinical, pathological and aetiological differences found among the beta A4-amyloidosis.