Effect of PD-1/PD-L1 and LAG-3/MHC II blockade on BLV-specific IFN-γ response. PBMCs of BLV-infected AL (A; n = 12) and PL cattle (B; n = 6) were cultured with blocking mAbs (anti-PD-L1 and anti-LAG-3 mAbs; 10 μg/mL) or rat IgG control in the presence of FLK-BLV antigen (2%) for 6 days. IFN-γ production for each animal was measured by ELISA in duplicate. Bars indicate group median response. Significant differences between each group were determined using Friedman test, where P < 0.05 and P < 0.01, indicated by asterisks (* and **, respectively).