Fig. 2

Positive and negative controls. (A) Strong interaction PLA signals as a positive control for the PD-1/PD-L1 interactions. This image shows the germinal centers where it is expected to see PD-1/PD-L1 interactions between B and T cells. (B) Omitting the PD-L1 antibody and performing isPLA using the anti-PD1 antibody and a rabbit isotype control reveals no background or non-specific binding in these negative controls. (C) Staining with anti-PD-L1 and mouse isotype control with the PD-1 antibody omitted shows no background or non-specific binding in these negative controls. Scale = 100 μm