In line with previous findings on the ability of IDO-competent myeloma cells to tip the Th1/Th2 balance in favor of Th2 cells [19], we found that IDO-expressing AML blasts dampened the in vitro production of IFN-γ by T cells, an effect that was reverted by the IDO chemical inhibitor 1MT. The gene discussed is IDO1; the disease is acute myeloid leukemia.