To determine the role of IDO1 in the developmental process of atherosclerosis, the effects of several designated treatments, “oxLDL”, “IFN-γ”, “oxLDL+IFN-γ” and “IFN-γ+oxLDL”, on the expression of IDO1 and the degree of foaming were evaluated, as well as IDO1 inhibitor-mediated reversion of the effects of these treatments, were also investigated. This evidence concerns the gene IDO1 and atherosclerosis.