Distribution of clusterin in Alzheimer brain tissue.

The immunohistochemical distribution of clusterin (SP40,40, SGP-2) was determined in Alzheimer disease (AD) and normal human brain tissue and compared with the distributions of vitronectin, protectin and the complement membrane attack complex (MAC). Antibodies to all four proteins showed staining of dystrophic neurites and neuropil threads in AD tissue, and residual serum in normal tissue, but only antibodies to clusterin and vitronectin strongly stained amyloid deposits in senile plaques. The clusterin antibody also showed punctate staining of some normal appearing AD pyramidal neurons, and very scattered staining of intracellular neurofibrillary tangles. Clusterin, vitronectin and protectin are all believed to inhibit membrane insertion by the MAC, and these data are consistent with upregulation of all three proteins in response to MAC formation in AD, and with a neuronal origin of clusterin.