Is Alzheimer's disease an apolipoprotein E amyloidosis?

The presence of the apolipoprotein E4 allele has been identified as a major risk factor for late-onset Alzheimer's disease. Apolipoprotein E has also been found immunohistochemically in Alzheimer's disease lesions. We biochemically isolated amyloid beta 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 beta and apolipoprotein E amyloid fibrils.