PDCD1 and nasopharyngeal carcinoma: We further performed multiplex immunohistochemistry (IHC) staining of NPC biopsies and confirmed the physical juxtapositions of CD80-expressing DC_C3_LAMP3 cells (CD80+) and CTLA4-expressing Treg cells (CD3+CD4+FOXP3+), as well as PD-L1-expressing DC_C3_LAMP3 cells (CD80+) and PD-1-expressing CD8+ T cells (CD3+CD8+; Fig. 6c, d).