Indoleamine 2,3-dioxygenase and immune tolerance in the gallbladder carcinoma

Indoleamine 2,3-dioxygenase(IDO)is the rate-limiting enzyme in the catabolism of trypto-phan along the kynurenine pathway.Over expression of IDO is one of the reasons which are responsible for immune tolerance of tumor.IDO also affects the effects of the vaccine of the dendritic cell in the tumor therapy.Lipopolysaccharide(LPS),cytokines and so on can regulate the expression of IDO via different regulating mechanisms.IDO participates in the local immune tolerance of tumor by three kinds of mechanisms.Further research on this immunological regulatory mechanism will be significant for tumor immunotherapy. Key words: Indoleamine 2,3-dioxygenase; Immune tolerance; Dendritic cell; Gallbladder neoplasms ; Tryptophan