Is Alzheimerʹs disease an apolipoprotein E amyloidosis?

The presence of the apolipoprotein E4 allele has been identified as a major risk factor for late-onset Alzheimerʹs disease. Apolipoprotein E has also been found immunohistochemically in Alzheimerʹs disease lesions. We biochemically isolated amyloid β from senile plaques and found that a carboxyl-terminal fragment (residues 216-299) of apolipoprotein E co-purified. In vitro this fragment from recombinant apolipoprotein E could form amyloid-like fibrils, which were Congo-red positive. Thus senile plaques may contain both amyloid β and apolipoprotein E amyloid fibrils.