Figure 1. Aβ immunization results in trafficking of T cells to sites of Aβ plaques in the brain parenchyma.

APP/IFN-γ Tg mice aged 9 months were immunized with Aβ and killed 19 days later. Brain sections were immunolabeled for Aβ plaques co-localized with lymphocyte subpopulations and activated microglia. (A) Brain sections derived from a representative Aβ-immunized APP/IFN-γ Tg mouse (n = 11) were immunolabeled with anti-CD4 (a, red), anti-Aβ (b, blue), and anti-CD11b (c, green) antibodies. The merged panel is shown in d. Bar represents 200 µm. (B) Three-dimensional representation of Z-stalk images taken from a representative compact Aβ plaque co-localized with CD11b⁺ microglia (green) and CD4 T cells (red) in the hippocampus. Bar represents 20 µm. (C) Co-localization analysis of CD4 T cells and CD11b-labeled plaques. Using Volocity 3D image analysis software (Improvision, Waltham, MA, USA), we set an intensity threshold to mark only those areas with CD11b^high microglia, representing Aβ plaques. Columns represent percent CD11b-labeled plaques with and without co-localized CD4 T cells in each of the analyzed sections [n = 3 (3 brain sections per mouse); means ± SD; P<0.001, Student's t test].