PD-L1 blockade increases virus-specific CD8⁺ T cell motility. (A and B) Splenic mean track velocities (left) and motility coefficients (right) for CD8⁺ P14 (A) and CD4⁺ SMARTA cells (B) in the red pulp were quantified at 0.5 and 4 h after i.v. injection of anti–PD-L1 (red) or isotype control (blue) antibodies on day 7. Asterisks denote statistically significant differences (P < 0.05). Each dot represents the track of an individual T cell. Data are representative of four independent experiments.