MOLECULAR AND CELLULAR CHARACTERIZATION OF THE MEMBRANE ATTACK COMPLEX, C5B-9, IN ALZHEIMERS-DISEASE

The membrane attack complex, C5b-9, is of considerable importance in m any inflammatory reactions. It is the terminal, cytolytic component of both classical and alternative pathway activation, and its presence p resupposes other potentially destructive complement constituents, incl uding anaphylotoxins and opsonins. We have characterized C5b-9 and its C9 constituent in the Alzheimer's disease (AD) and nondemented elderl y (ND) brain using immunohistochemistry at the light and electron micr oscopic levels, Western blot analysis, and the reverse transcriptase p olymerase chain reaction. We have also conducted in vitro ELISA assays of amyloid beta-peptide-stimulated SC5b-9 production. C5b-9 is abunda ntly present in Alzheimer's disease cortex, associated with neurofibri llary tangle containing neurons, dystrophic neurites within neuritic p laques, and neuropil threads, bur is weakly detected, if at all, in no ndemented elderly cortex under the same conditions. Staining of Alzhei mer's disease sections is abolished both by deletion of primary antibo dy or preabsorption with purified SCSb-9. (C) 1997 Elsevier Science In c.