IDO1 and neoplasm: In addition, different studies have demonstrated that breast malignancies are associated with the induction of different subpopulations of DC (myeloid, mDC or plasmacytoid, pDC) at different stages of maturation in the tumor, lymph nodes or blood, which actively promote T cell anergy and suppression and/or which trigger tumor-promoting Treg induction by a variety of mechanisms such as L-Arginine depletion (124), PD-L1 (125), TGFβ, IDO (126) or ICOS-ligand (127).