In essence, PD-L1 does not act in isolation but as part of a dynamic immune contexture, and its prognostic and therapeutic significance in GCA is best understood in light of tumor-infiltrating immune cells (CD8+ effector T-cells and even FOXP3+ regulatory T-cells) that collectively shape the tumor’s response to immune checkpoint blockade [71,72]. This evidence concerns the gene FOXP3 and temporal arteritis.