Blocking PD-L1 in this case could dampen anti-tumor immunity.37 In support, we found that aged splenic DCs in tumor-naïve mice have higher co-expression of PD-L1 and CD80 versus young, which suggests a general age-related effect, but we also noted higher DC PD-L1/CD80 in tumor infiltrating DC. This evidence concerns the gene CD80 and neoplasm.