Figure 2

Absence of PD-L1 reduces cerebral cell infiltration and inflammatory responses in the ischemic brain. Ninety-six hours after MCAO, mononuclear cells were isolated from the brains of WT, PD-L1^-/-, and PD-L2^-/- male mice and analyzed. (A) Total cell count via hemocytometer. Values represent mean numbers (± SEM) of indicated cell subsets from 9 to 11 mice per group, from three separate experiments. (B) CD11b⁺CD45^high activated microglia/monocytes. (C) CD4⁺ T cells and (D) CD8⁺ T cells were obtained from the non-ischemic (left) and ischemic (right) hemispheres of WT, PD-L1^-/-, and PD-L2^-/- mice. (B,C,D) Values represent mean numbers (± SEM) of indicated cell subsets, gated on live leukocytes (by PI exclusion) from eight to nine mice per group, from at least three separate experiments. Determinations of (E) TNF-α production by CD11b⁺CD45^high activated microglia/monocytes and (F) TNF-α⁺CD3⁺ T cells in the non-ischemic (left) and ischemic (right) hemispheres from WT, PD-L1^-/-, and PD-L2^-/- mice at 96 hours post-MCAO. Values represent mean numbers (± SEM) of indicated cell subsets from four to five mice of each group, from at least two separate experiments. Statistical analysis was performed with ANOVA followed by Tukey’s multiple comparison post-hoc test. Significant differences between sample means are indicated (#P ≤0.05; ##P ≤0.01; ###P ≤0.001 as compared to their respective left hemisphere and *P ≤0.05; **P ≤0.01 as compared to the ischemic right hemisphere of PD-L1^-/- mice post-MCAO). ^-/^-, knockout; ANOVA, analysis of variance; MCAO, middle cerebral artery occlusion; PD-L1, programmed death-1 ligand 1; PD-L2, programmed death-1 ligand 2; PI, propidium iodide; SEM, standard error of the mean; TNF, tumor necrosis factor; WT, wild-type.