Figure 3.

IDO enzymatic activity in human serum samples analyzed by HPLC. Kyn and tryptophan concentrations were measured by high-performance liquid chromatography in serum samples collected from 24 healthy donors and 47 PBC patients. The Mann Whitney unpaired t-test statistical analysis was used to compare the control and patient groups. (A) Kyn and tryptophan ratio (area under peak). (B) Kyn and tryptophan ratio (height of peaks). Kyn, kynurenine; Trypt, tryptophan; IDO, indoleamine 2,3-dioxygenase; PBC, primary biliary cirrhosis.