Modulation of indoleamine 2,3-dioxygenase by interferon-gamma in human placental chorionic villi

The effect of interferon-gamma on indoleamine 2,3-dioxygenase, a tryptophan catabolizing enzyme, was studied in cultured human placental chorionic vil li. The activity of indoleamine 2,3-dioxygenase was markedly stimulated by interferon-gamma in a time- and concentration-dependent manner. Interferon- alpha and interferon-beta also showed a slight stimulatory effect on indole amine 2,3-dioxygenase activity. The level of indoleamine 2,3-dioxygenase mR NA expression (determined by reverse transcription-polymerase chain reactio n) was also enhanced by interferon-gamma, Interleukin-4 showed a dose-depen dent inhibitory effect on interferon-gamma-induced stimulation of indoleami ne 2,3-dioxygenase activity and mRNA expression.