Interferon-gamma-dependent/independent expression of indoleamine 2,3-dioxygenase: Studies with interferon-gamma-knockout mice

Abstract

The role of IFN-γ in the expression of indoleamine 2,3-dioxygenase (IDO), a tryptophan oxidizing enzyme, in mouse tissues under physiological and pathological conditions was investigated using IFN-γ-knockout mice. The results revealed that i) the expression of IDO in the large intestine or in the cecum is mediated by IFN-γ, ii) for the systemic IDO induction under endotoxin shock, IFN-γ is a dominant inducer but not essential, and an IFN-γ-independent mechanism is also operative, iii) the systemic induction of IDO caused by IL-12 or Pokeweed mitogen is mediated by IFN-γ, and iv) the constitutive IDO expression in the epididymis is IFN-γ-independent.