Figure 5.

Microglial Expression of MHCII Is Required to Stimulate the Effector Functions of ICV-Injected Aβ-Th1 Cells within the Brain Parenchyma

Bone marrow chimera (BMC) mice (n = 12) were generated, and after 8 weeks, six of them were ICV-injected with Aβ-Th1 T cells, whereas the other six were left untreated. The mice were perfused at 28 dpi, and their brains were excised and analyzed by IHC and flow cytometry.

(A) Representative IHC images of cortical (top images) and hippocampal (bottom images) brain sections from untreated BMC mice (left) and from BMC mice that were ICV-injected with Aβ-Th1 T cells (Th1→BMC, right) (n = 5 mice per group) and immunolabeled with DAPI nucleus counterstain (blue). Green cells are infiltrating macrophages. A quantitative analysis (right graphs) of the number of GFP+ cells per volume of cortical or hippocampal section was performed with IMARIS. Scale bars, 200 μm. Bars represent means ± SEM, and each symbol represents an individual mouse.

(B) Representative IHC image showing Aβ plaques co-localized with infiltrated GFP+ BM cells in brain sections derived from either BMC or Aβ-Th1→BMC mice and immunolabeled with the DAPI nucleus counterstain (blue) (n = 5 mice per group). Scale bars, 200 μm (left images) and 30 μm (right images).

(C) Representative IHC image showing Aβ plaque load in brain sections derived from untreated (UT), BMC, or Aβ-Th1→BMC mice and immunolabeled with anti-Aβ (gray) and a DAPI nucleus counterstain (blue). The quantitative analysis (right graph) of the plaque load per volume of cortical section was performed with IMARIS. Scale bars, 200 μm. Bars represent means ± SEM.

(D) Representative IHC images of brain sections derived from untreated BMC mice (top images) or from Aβ-Th1→BMC mice (bottom images) and immunolabeled with anti-MHCII (blue) and a DAPI nucleus counterstain (gray). Green cells represent infiltrating BM cells. Scale bars, 30 μm. ***p < 0.001 [(A) Student's t-test, (C) one-way ANOVA].