Immune evasion is one of the identifying hallmarks of cancer, and researchers are trying to identify the complex mechanisms that enable cancer cells to evade the host’s immune system. Cancer cells use the indoleamine 2,3-dioxygenase (IDO) pathway to suppress the host’s immune response in order to facilitate survival, growth, invasion, and metastasis of malignant cells. The IDO pathway is active in many tumors, providing a direct defense against T cell attack. The IDO pathway also is active in many antigen-presenting cells, resulting in peripheral tolerance to tumor-associated antigens.
Image from http://newlinkgenetics.com/ido-pathway-inhibitors
The two IDO isozymes, IDO1 and IDO2, are normally involved in the metabolic breakdown of the amino acid tryptophan. IDO exhibits its immune-dampening effect by suppressing the response of macrophages and effector T cells. The exact mechanism of this immunosuppression is unclear, but it likely involves tryptophan starvation of sensitive T-cells and/or the build-up of toxic metabolites (kynurenines) from tryptophan metabolism, leading to cell cycle arrest and death of effector T cells within the cancer cell microenvironment. IDO expression also directly activates the regulatory T cells that shut down the immune response, which amplifies the suppressive effect.
IDO1 activity. Data shown is lot-specific
IDO1 inhibition, measured using the IDO1 Inhibitor Screening Assay Kit, Catalog #72021. Data shown is lot-specific
- IDO1 protein, IDO2 protein & TDO protein
- IDO inhibitors
- IDO1 assay, IDO2 assay & TDO assay
- Screening service