Figure 2. Peripheral IDO deficiency has no effect on brain tumor-infiltrating T cell levels and survival.

Wild-type (WT) (white bars) or indoleamine 2,3 dioxygenase 1-deficient (IDO^−/−; black bars) mice were intracranially-injected 4×10⁵ normal GL261 cells. The frequency and absolute numbers of (A) total CD4⁺ T cells, CD8⁺ T cells and CD4⁺FoxP3⁺ regulatory T cells isolated from the brain and bilateral deep and superficial cervical draining lymph nodes (dLN) of tumor-bearing mice were analyzed at 3 weeks post-intracranial injection (wp-ic). All T cell populations were initially identified by the expression of CD3. (B) Representative flow cytometric plots demonstrate the gating strategy utilized for the identification of total CD3⁺CD4⁺, CD3⁺CD8⁺ and CD3⁺CD4⁺FoxP3⁺ T cells. Bar graphs in figure A are shown as mean ± SEM and are representative of two independent experiments (n = 3 – 5 mice/group). (C) The Kaplan-Meier curve represents mouse survival times over a time course of 50 days (n = 7 – 9 mice/group).