[Indoleamine 2,3-dioxygenase in oncology and psychiatry]

In the last years an attention has been paid to the indoleamine 2,3-dioxygenase (IDO), an enzyme catabolising L-tryptophan to kynurenine. Growing evidence has been accumulated that kynurenine and other metabolites of tryptophan play an important role in the pathogenesis of malignant tumours and some neurological and psychiatric disorders. The gradual recognition of mechanisms operative in their development may help to identify etiological factors involved and becomes prerequisite for the progress in their diagnostics and therapy. In oncology, great effort is directed to the development and testing of substances inhibiting IDO activity. It is expected that some of them will be utilized in the immunotherapy of cancer. In the field of psychiatric disorders, namely in schizophrenia and depression, the role of IDO is linked to immune dysregulation. In those diseases, IDO represents a potential mediator between immunological reactivity and alterations of the brain function. Changes in the IDO activity may also mediate interaction between the genetic predisposition and environmental factors.