It has also been reported that merely activating the immune system, such as by adoptive T cell transfer using a conventional lymphoblastoid cell line-reactivated preparation [38,39], or by vaccination with dendritic cells [40,41], might be inadequate for immunotherapy, and may result in up-regulation of IFNγ and/or TNFα production, leading to IDO expression in tumor cells [41]. This evidence concerns the gene IDO1 and neoplasm.