IDO-positive tumor- and stroma-infiltrating cells represented a heterogeneous population of immune cells consisting of HLA-DR−CD14+IDO+ MDSC-like cells, HLA-DR+CD14+IDO+ dendritic/macrophage-like cells, HLA-DR−CD14−IDO+-, and HLA-DR+CD14−IDO+ cells (Figure 2A). This evidence concerns the gene IDO1 and neoplasm.