Fig. 6. CTLs accumulate in damaged microvessels of EC-HA⁺ mice.

Representative brain images of EC-HA⁺ mice 4 days after adoptive transfer of cytotoxic CD8⁺ T cells (n = 6). a Accumulation of leukocytes in CNS microvessels. b Expression of MHC class-I molecules (green) on CD31⁺ (red) ECs; nuclei marked with TO-PRO-3 (blue). c Presence of GrB⁺ (red) CD8⁺ (blue) T cells in vessel lumen (L) of a battered CD31⁺ (green) blood vessel. Par parenchyma d GrB⁺ granules (red, arrowheads) CD8⁺ cells (blue) in close contact with the lumen of a small CD31⁺ blood vessel (green). e Representative image exhibiting CD31⁺ (brown) endothelium loss (arrowheads) in CNS microvessels of EC-HA⁺ mice following CD8⁺ T cell transfer. f Apoptosis and g DNA fragmentation (arrowheads) of CD31⁺ ECs (brown) detected with TUNEL staining (black). h Microhemorrhages in close proximity to destroyed vessels. Scale bars 10 µm. i Percentage of endothelial apoptosis assessed condensed nuclei in CD34⁺ endothelial cells (74–206 cells per mouse) of EC-HA⁻ (closed blue circles) or EC-HA⁺ mice (closed cayenne diamonds) (n = 6 per group). Scale bars 100 µm. Statistical analysis was performed by unpaired Student’s t test. Error bars indicate the mean ± s.d. p value: **p < 0.01. Source data are provided as a Source Data file. j Deposition of IgG in the hippocampus and turnbull blue staining (TBB) of the cerebellum of EC-HA⁻ and EC-HA⁺ mice after CTL transfer. Scale bars 500 µm. Data from two independent experiments, 5–6 mice per genotype are shown. k Representative small ischemic lesion in and above the corpus callosum at day 7 post-transfer in an EC-HA⁺ mouse. APP labeling (arrowhead) reveals axonal damage. Focal loss of astrocytes is visualized by the absence of GFAP (arrowhead). Detection of carbonic anhydrase II (CAII) reveals the focal loss of oligodendrocytes (arrowhead). The CD31 staining shows loss of ECs (arrowhead). Nuclear counterstaining was performed with hematoxylin (blue) (n = 6 per group).