Consistently, in this study we also observed that some IDO high-expressing myeloid cell-like karyocytes in TDLNs displayed positively linear correlation to the IDO expression on cancer cells in PTs, which might participate in the mutual cross-talk between IDO+ cancer cells and Foxp3+ Tregs and further magnified the immunosuppressive cascade triggered by IDO. This evidence concerns the gene IDO1 and cancer.