alpha-1-antichymotrypsin interaction with A beta (1-40) inhibits fibril formation but does not affect the peptide toxicity.

Recent studies have shown that senile plaque-associated or glial-derived proteins can prevent fibril formation of beta-amyloid peptide (A beta), while increasing the neurotoxicity of the latter (in the case of glutamine synthetase, apolipoprotein J or thrombin). alpha-1-Antichymotrypsin (ACT) is a glial-derived protein associated with senile plaques in the Alzheimer's brain. In this report we show that ACT, a minor protein component of beta-amyloid deposits, is able to inhibit A beta (1-40) aggregation into fibrils, but unable to modulate the toxicity of A beta (1-40) in primary rat hippocampal cell cultures. These results are discussed in terms of the potential role of glial-derived proteins on A beta aggregation and neurotoxicity.