Fig. 5.

CD4⁺ and CD8⁺ T lymphocytes in the substantia nigra and the amygdala. a, c Representative image of parenchyma infiltrating CD4⁺ and CD8⁺ T lymphocytes in the substantia nigra of a control (left) and a Parkinson’s brain (right). The dark brown pigment is neuromelanin within dopaminergic neurons; the smaller CD4⁺ and CD8⁺ T cells are shown in the higher magnification inserts indicated by black squares. b, d Percentage of controls, PDND and PDD cases that show 0–10 or more than 10 infiltrating CD4⁺ (χ² = 75.15, p < 0.0001) or CD8⁺ T cells (χ² = 11.31, p = 0.0035) in the entire nigral section e, g Representative image of parenchyma infiltrating CD4⁺ and CD8⁺ T lymphocytes in the amygdala of a control (left) and a Parkinson’s brain (right). CD4⁺ and CD8⁺ T cells are shown in the higher magnification inserts indicated by black squares. f, h Percentage of controls, PDND and PDD cases that show 0–10 or more than 10 infiltrating CD4⁺ (χ² = 37.68, p < 0.0001) or CD8⁺  T cells (χ² = 3.92, p = 0.141) in the entire amygdala section. i Quantification of parenchymal CD4⁺ (p = 0.023, Control vs PDD p = 0.018) and CD8⁺ T lymphocytes (p = 0.102) per mm² in the substantia nigra. Control n = 12, PDND n = 16, PDD n = 10. Quantification of parenchymal CD4⁺ (p = 0.081) and CD8⁺ T lymphocytes (p = 0.434) per mm² in the amygdala. Control n = 10, PDND n = 12, PDD n = 11. Kruskal–Wallis with Dunn’s multiple comparisons test. PDND Parkinson’s disease no dementia, PDD Parkinson’s disease dementia. Scale bar: 100 μm. Scale bar (insert): 20 μm. *p < 0.05