Characterization of new polyclonal antibodies specific for 40 and 42 amino acid-long amyloid β peptides: Their use to examine the cell biology of presenilins and the immunohistochemistry of sporadic Alzheimer's disease and cerebral amyloid angiopathy cases

Background: In Alzheimer's disease (AD), the main histological lesion is a proteinaceous deposit, the senile plaque, which is mainly composed of a peptide called Aβ. The aggregation process is thought to occur through enhanced concentration of Aβ40 or increased production of the more readily aggregating 42 amino acid-long Aβ42 species. Materials and Methods: Specificity of the antibodies was assessed by dot blot, Western blot, ELISA, and immunoprecipitation procedures on synthetic and endogenous Aβ produced by secreted HK293 cells. Aβ and p3 production by wild-type and mutated presenilin 1-expressing cells transiently transfected with βAPP751 was meningeal and cortical arterioles whereas FCA3542 only faintly labels such structures. Conclusions: Polyclonal antibodies exclusively recognizing Aβ40 (FCA3340) or Aβ42 (FCA3542) were obtained. These demonstrated that FAD- linked presenilins similarly affect both p342 and Aβ42, suggesting that these mutations misroute the βAPP to a compartment where γ-secretase, but not α-secretase, cleavages are modified. Overall, these antibodies should prove useful for fundamental and diagnostic approaches, as suggested by their usefulness for biochemical, cell biological, and immunohistochemical techniques.