Negative Impact of Hypoxia on Tryptophan 2,3-Dioxygenase Function

Figure 6

Loss of TDO immunoregulatory function in HeLa-hTDO cells under hypoxic conditions. T cell proliferation experiments: HeLa-hTDO cells were prestimulated with or without tetracycline (10 ng/mL) for 72 h under normoxia (20% O₂) or hypoxia (1% O₂). Then the supernatants were harvested and served as cell culture medium for freshly isolated peripheral blood lymphocytes (PBL).  PBL/well were activated in 96-well plates with a monoclonal anti-CD3 antibody (OKT3) and T cell proliferation was determined after three days by adding ³H-thymidine for 24 h. The incorporation of ³H-thymidine was detected using liquid scintillation spectrometry (1205 Betaplate, PerkinElmer, Rodgau Jügesheim, Germany). A significant alteration of T cell proliferation as compared to the respective control group is marked with asterisks (; n.s. = not significant) and was calculated via a two-tailed, unpaired t-test. (a) Single experiment with three replicates and (b) summary of three independent experiments with three replicates each. The bars indicate the mean value SD (a) or SEM (b).

(a)

(b)