Indoleamine 2,3-dioxygenase in tumor induced tolerance

Abstract

Objective: To review the recent studies about the role of indoleamine 2,3-dioxygenase (IDO) in tumor induced tolerance.

Data sources: Published articles (1978 - 2009) on IDO and tumor induced tolerance were selected from Medline.

Study selection: Articles selected were relevant to development of IDO in tumor induced tolerance. Of all originally identified articles, 50 specially addressed the stated purpose.

Results: Recent work has revealed IDO at high levels in tumors and in tumor-draining lymph nodes and a close relationship between IDO activity and the regulatory T cells.

Conclusion: Up-regulation of IDO is proven to be a mechanism of acquired tolerance in tumors, in which the closely coupled positive feedback system between IDO and regulatory T cells may be considered to play an important role.