Up regulation of PD-l ligand PD-L1 expression on splenic B-cells and macrophages following chronic spinal cord injury (SCI). (A) Representative histogram plots show PD-L1 expression on gated B220+ B-cells, CD11b+ macrophages and CD11c+ dendritic cells from uninjured (CT) and T9-SCI mice at chronic phase after injury (SCI). (B) Bar graphs show the mean ± SEM of PD-L1 mean fluorescence intensities (MFI) in gated B-cells, macrophages and dendritic cells from CT and SCI mice. Ten thousand events gated on live singlets were collected. n = 4 mice per group. *P < 0.05, **P < 0.01, one-tailed Student’s t-test.