The signal transduction mechanism responsible for gamma interferon-induced indoleamine 2,3-dioxygenase gene expression.

We examined the signal transduction mechanism responsible for the gamma interferon-induced indoleamine 2,3-dioxygenase (IDO) gene expression in a human monocytic cell line, THP-1. Our results suggest that gamma interferon-induced activation of protein tyrosine kinase is a prerequisite for gene expression and that activation of protein kinase C and another unknown signal(s), both of which are transduced by the protein tyrosine kinase, synergistically induce IDO gene expression. Neither Ca2+ influx nor cyclic nucleotide-dependent kinases were suggested to be involved in the signaling pathway.