Reduction in DC allostimulatory capacity after 4-OH-IF and BSO treatment and restoration with GSH-OEt. (A) DCs were treated with 4-OH-IF (100 μM) alone for 90 minutes on day 8 or with 4-OH-IF for 90 minutes and then with GSH-OEt (0.4 mM) for 5 hours. Untreated cells from parallel day-8 cultures were used as controls. DCs were irradiated and incubated with PBLs (10⁵/well) at different PBL/DC ratios for 6 days. Results are shown for the PBL/DC ratio of 32:1. ^*P < .05. (B) DCs were treated with BSO (0.5 mM) alone on day 7 for 24 hours or with BSO for 24 hours and then with GSH-OEt (5 mM) for 5 hours. DCs were irradiated and resuspended in RPMI medium plus 10% FCS and incubated with allogeneic PBLs (10⁵/well) in 96-well plates at PBL/DC ratios ranging from 2:1 to 64:1 for 6 days. Results are shown for the PBL/DC ratio of 64:1. BSO-treated DCs alone, 4-OH-IF-treated DCs alone, untreated DCs alone, or PBLs alone were used as controls. The amount of [3H]-thymidine incorporated during the last 24 hours of culture was measured (A-B). Results are expressed as the mean ± SD of cpm values of triplicate cultures from 1 of 3 representative experiments. ^*P < .05. (C) 4-OH-IF and 4-OH-IF plus GSH-OEt-treated DCs and (D) BSO and BSO plus GSH-OEt-treated DCs were also washed, and GSH levels were measured by HPLC. Untreated cells were used as controls. Results are expressed as the percentage of control values and represent the mean ± SD from 3 treatments. ^*P < .05.