Amyloid P component and other acute-phase proteins associated with cerebellar A beta-deposits in Alzheimer's disease.

It is established that amyloid P (AP) component and complement proteins are associated with amyloid beta (A beta)-protein deposits in the cerebral cortex of Alzheimer's disease (AD) subjects. Here, we used immunocytochemical methods to examine the association of these acute-phase proteins with the characteristic diffuse plaques of cerebellum in AD. We observed AP and complement C3d, C1q, C5 and C4bp immunoreactivities in most A beta-protein-reactive plaques of the cerebellum. Further, a1-antichymotrypsin immunoreactivity was apparent in at least 60% of all the cerebellar diffuse plaques examined. Cerebellar tissue bearing the A beta-protein deposits also often exhibited marked angiopathy in the pial vessels. We suggest that diffuse plaques of the cerebellum also acquire components of the chronic inflammatory response evident in neocortical plaques.