IMMUNOCYTOCHEMICAL EVIDENCE THAT THE BETA-PROTEIN PRECURSOR IS AN INTEGRAL COMPONENT OF NEUROFIBRILLARY TANGLES OF ALZHEIMERS-DISEASE

Amyloid beta (Abeta) immunoreactivity has been demonstrated in all ext racellular neurofibrillary tangles (E-NFT) and most intraneuronal neur ofibrillary tangles (I-NFT). We undertook this immunocytochemical stud y to understand the relationship between Abeta immunoreactivity locali zed in NFT and beta-protein precursor (betaPP). We found epitopes of a mino-, mid-, and carboxyl-terminal domains of betaPP in I-NFT and the majority of E-NFT. NFT retained betaPP after ionic detergent extractio n, demonstrating that betaPP is an integral component of NIT. Finding betaPP in regions of Abeta immunoreactivity raises the possibility tha t betaPP or its fragments associate with amyloid, and that the stabili ty of Abeta is responsible for its dominance in amyloid deposits.