Tetravalent Aβ1–15 vaccine reduces TCR-positive cell infiltration and up-regulates p75 in Tg2576 brains compared to Aβ42 vaccine

In order to investigate the effect of Aβ vaccines on T cell infiltration into the brain, we immunized Tg2576 mice with two adenovirus vaccines containing tetravalent Aβ1–15 (4×Aβ15) or Aβ42. TCR-positive cells were found in the ventricle, parenchyma, and surrounding the vasculature, especially concentrating in the periventricular parenchyma, the reticular part of the substantia nigra and the corpus striatum. Compared to the Aβ42 group, TCR-positive cells in the tetravalent (4×) Aβ15 group were significantly decreased. Both vaccines down-regulated neurotrophic and inflammatory factors, but the 4×Aβ15 vaccine up-regulated TrkA and p75 compared with the Aβ42 vaccine. The results suggest that the 4×Aβ15 vaccine might be safer and more beneficial than the Aβ42 vaccine.