Figure 5

Limited demyelination and immune cell infiltration was detected in the spinal cords of L31/CD4 ^-/- mice. Only isolated myelin loss was found in the spinal white matter of symptomatic L31/CD4^-/- mice together with few CD8⁺ T cell clusters (A). CD8⁺ T cells were also found in the grey matter of some symptomatic L31/CD4^-/- mice, gathered near motor neurons (A). Occasionally very few isolated CD8⁺ T cells were found even in pre-symptomatic L31/CD4^-/- mouse spinal cords (A). In symptomatic L31/CD4^-/- mice, robust spinal microglia activation was detected, mainly in the grey matter. Iba-1⁺ microglia were clustered at the dorsal and ventral horns (B). Morphological changes were revealed with confocal microscope (B-left panels). In the white matter of diseased spinal cord, some demyelinated spots (C-arrows) were found in the dorsal column where Iba-1⁺ microglia gathered (C). Quantitative analysis of CD11b⁺CD45⁺ microglia and CD8⁺ T cells using FACS (n = 3/group) confirmed the immunohistochemistry observation (*: p < 0.05, **: p < 0.01) (D). Increased B7.2 expression was found in symptomatic spinal cords, on ramified Iba-1/B7.2 double labelled microglia, or on round B7.2 single labelled cells, presumably CD8⁺ T cells (E). Scale bars: A, 100 μm; B, left, 500 μm, right, 10 μm; C, 100 μm; E, 50 μm.