PD-L1 blockade inhibits cell apoptosis in spleen and thymus. Mice underwent a sham procedure, CLP, CLP plus anti-PD-L1 or isotype administration (n = 5 for each group). Spleen and thymus were harvested 24 h after surgery. (A) Representative sections analyzed by an in situ TUNEL assay. (B) Percent of the TUNEL-positive cells is used to show the cell apoptosis in spleen and thymus of the 4 groups. * P <0.05.