PDCD1 and neoplasm: Physical interaction of PD-1+ICOS+ Th1 or Th17 cells with MHC II+ DCs in the TME would likely enhance cross-priming of antitumor CD8+ T cells within the tumor-associated TLSs, allowing for local antitumor T cell repertoire expansion and diversification that is distinguishable from T cell priming in the periphery.