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.