Effect of hypoxia on monocyte-derived DC maturation. (A) Human monocyte–derived DCs were cultured for 18 hours under normoxic or hypoxic conditions in the presence or absence of LPS and the surface expression of different maturation markers was analyzed by flow cytometry. Cells were stained with CD80–R-PE, CD83-Alexa488, CD86-APC, CD40–R-PE, and MHC II–Alexa488 antibodies, or with isotype controls. Left panels: dotted line indicates normoxia; dashed line, hypoxia; and solid line, isotype. Results are representative of 3 independent experiments. Right panels: the average of 3 independent experiments is shown. Data are means plus or minus SD. *P < .05 versus DCs matured in normoxia. (B) Effect of hypoxia on costimulatory functions of DCs. After 3 days of coculture with DCs, CD4⁺ T-cell proliferation (left) and IFN-γ production (right) were evaluated by enzyme-linked immunosorbent assay (ELISA). Data are means plus or minus SD of 3 different experiments. *P < .05 versus normoxic counterparts.