Figure 2. The cross-primed T_CD8 response to T Ag is augmented in the absence of IDO.

WT and IDO^−/− mice were injected i.p. with allogeneic T Ag⁺ KD2SV cells. Nine days later, the frequencies (A) and absolute numbers (B) of T Ag-specific T_CD8 recognizing site IV, total T Ag-specific T_CD8 that synthesize IFN-γ after incubation with C57SV cells, and total alloreactive T_CD8 that produce IFN-γ after incubation with KD2SV cells were determined by ICS as described in Materials and Methods. Background obtained from wells receiving no peptide was subtracted and values are presented as mean ± SEM of 8 mice/group pooled from independent experiments.