PD-1/PD-L1 interactions likely dampen vaccine responses by two mechanisms: (i) in the draining lymph node where vaccine adjuvant-induced inflammation results in PD-L1 expression on antigen-presenting cells that inhibits maximal expansion of vaccine-generated T cells,82 and (ii) in the tumor itself whereby “adaptive immune resistance” 51 is generated by T cells secreting IFNγ that induces PD-L1 upregulation on neighboring cells leading to T cell anergy. This evidence concerns the gene CD274 and neoplasm.