IDO1 and melanoma: CD163+ TAMs represent the most mature and immunosuppressive, characterized by an increased expression of genes associated with a M2-like signature (including Il4ra, Mrc1, Stab1 and Slco2b1) or T cell suppression (Il10, Ido1 and Lgals1), and their specific depletion reduced significantly melanoma growth by driving the recruitment of inflammatory monocytes and subsequently CD4+ and CD8+ T cell recruitment and activation.