Figure 1.

PD-L1-mediated immune resistance by melanoma. In the vast majority of melanoma cases, tumor cells demonstrate an inducible rather than a constitutive pattern of programmed cell death ligand 1 (PD-L1) expression. Upon T-cell recognition of tumor antigen, an active antitumor immune response is generated that eventuates in lymphocyte expression of programmed cell death 1 (PD-1) and interferon release. In response to this immune attack, cancer cells and other inflammatory cells in the tumor microenvironment adaptively upregulate surface expression of PD-L1. In cutaneous melanoma, melanocyte PD-L1 display is not influenced by BRAF mutational status.