Expression of immune checkpoint proteins are increased on T cells in mice treated with sublethal whole body irradiation and anti-PD-L1. Myeloma bearing KaLwRij mice were treated with 500 cGy whole body irradiation 7 days after tumor cell injection. Treatment with anti-PD-L1 or control IgG (200 μg ip) was initiated 5 days later and specifically given 12, 14, and 19 days after tumor injection. Mice were euthanized at day 21, splenocytes were harvested, and the CD8 T cells were analyzed by flow cytometry for immune checkpoint protein expression. (A) Frequency of CD8+TIM-3+, CD8+LAG-3+ and CD8+2B4+ cells in spleens of anti-PD-L1 treated mice as compared with spleens harvested from control antibody (IgG1) treated mice. ***p < 0.001. (B) Expression of TIM-3 and PD-1, LAG-3 and PD-1 or 2B4 and PD-1 on gated CD8+ T cells. Data shown are representative of more than four independent analyses.