Accumulation of amyloid precursor protein in brain lesions of patients with Pick disease

Pick's disease immunohistochemistry: new alterations and Alzheimer's disease comparisons

Pick's disease (PD) brains were examined immunohistochemically for the expression of antigens known to be associated with Alzheimer's disease (AD) lesions. Most antibodies which label intracellular neurofibrillary tangles (NFTs) in AD were found to stain Pick bodies (PBs). Among them was the monoclonal antibody A2B5, which is known to recognize neuronal surface gangliosides. This result indicates that membrane proteins are probably incorporated into PBs as into NFTs. However, PBs, in contrast to NFTs, showed a paucity of staining for heparan sulfate glycosaminoglycan and basic fibroblast growth factor (bFGF). Staining for midkine, seen in senile plaques in AD, was not seen in PD. The relative lack of staining for these two neurotrophic factors in PD brain may reflect underlying mechanisms which are distinct from those in AD. We also describe two glial abnormalities in PD: glial fibrillary tangles and clusters of granules positive for the complement protein C4d in the hippocampal dentate fascia. These are presumably related to complement-activated oligodendroglia, and both pathological structures are more abundant in advanced cases, suggesting that they may be hallmarks of the disease progression.

Expression of the complement membrane attack complex and its inhibitors in Pick disease brain

The immunohistochemical localization of the complement membrane attack complex (MAC) was examined in Pick disease brain and compared with the distribution of three of its inhibitors, vitronectin, protectin and clusterin. Pick bodies were stained intensely for both the MAC and protectin, weakly for vitronectin, but negatively for clusterin. However, the clusterin antibody intensely stained some pyramidal neurons in affected cortical areas, including ballooned neurons. The present study indicates that a complement-mediated attack is associated with the formation of Pick bodies, and provides further suggestive evidence that clusterin may be a marker for active neuronal degeneration.