The increased circulating levels of some proinflammatory cytokines in symptomatic AIP, notably IFN-γ, IL-1β, IL-6 and TNF-α [107], could induce the extrahepatic enzyme IDO to increase production of Kyn, and hence of KA and possibly also AA, thus increasing the demand for PLP, and also production of proinflammatory Kyn metabolites, notably 3-HK, 3-HAA and quinolinic acid (QA). The gene discussed is IDO1; the disease is autoimmune pancreatitis.