Figure 5. IDO-mediated immunoregulatory effect is lost under hypoxia.

(A, B) Co-stimulation assay of 1.5×10⁵ PBMC and 0–10000 HFF cells/well. T-cells were activated by the anti-CD3 antibody OKT3. The T-cell proliferation in the absence (A) or presence (B) of supplemented tryptophan was determined by incorporation of [³H] thymidine. Data are given as T cell proliferation in % of the positive control (stimulated T cells under normoxia) +/− SEM. A significant increase of T-cell proliferation as compared to the positive normoxia control is marked with an asterisks, n = 3.