PDCD1 and cancer: To explore the relationship between BIR cells and TLS formation, we used a 42-gene signature for the detection of TLSs identified from transcriptomic analysis of human cancers, which included chemokine (CCL2, CCL3, CCL4, CCL5, CCL11, CCL14, CCL18, CCL19, CCL20, CCL21, CCL22, CXCL9, CXCL10, CXCL11, CXCL13, CCR1, CCR3, CCR5, CCR7, and CXCR3) and immune cell (BST1, CD4, CD5, CD6, CD38, CD40, CD200, CD274, CSF2, GFI1, ICAM1, ICOS, IGSF6, IL1R2, IL1RN, IL2RA, IRF4, PDCD1, SH2D1A, STAT5A, TIGIT, and TNFRSF17) signatures (4).