IDO1 and neoplasm: The capacity of tumor cells (MCF7 and M628) to induce senescence in naïve CD4+ T cells was investigated in the presence or absence of a panel of neutralizing antibodies against IL-10, TGF-β, TCRαβ, PDL-1, and MHC-class II, as well as the IDO inhibitor, 1-methyl-D-tryptophan (1-MT).