IFN-γ increases platelet Ido1 expression. (A) IFN-γ treatment increased platelet Ido1 expression (n = 3). (B) Anti-IFN-γ treatment during PyNL infection inhibited platelet Ido1 expression at day 7 after infection. Normalized relative intensity levels on day 7 of (C) TRP, (D) KYN, and (E) KTR as an indicator of IDO1 activity. (F) Normalized relative intensity levels of 5-HIAA at day 7 after infection (∗P < .05).