Human monocyte-derived immature DCs demonstrate 11β-HSD1 reductase activity. (A) Cortisone reductase (E → F) or cortisol dehydrogenase (F → E) activities as measured by thin-layer chromatography following preincubation of intact cells with 10^-7 M [³H]-labeled cortisol or cortisone (data shown as mean ± SEM; ^**P < .01 for reductase activity in imDCs versus monocytes, ^*P < .05 for dehydrogenase in imDCs versus monocytes, n = 4). (B) Cortisone reductase or cortisol dehydrogenase activities measured as shown in panel A during the first 7 days of DC culture (data representative of 2 independent experiments). (C) Cortisol concentrations as measured by competitive binding assay following incubation of monocytes in the presence of IL-4/GM-CSF media alone or 10^-6 M cortisone or 10^-6 M cortisol ± 18β-glycyrrhetinic acid (GA; cortisone versus cortisone plus GA, ^***P < .001 at day 3 and ^**P < .01 at day 7, n = 3). (D) H6PDH activities as measured by reduction of NADP⁺ by cell extracts derived from monocytes or imDCs. OD indicates optical density. Data are representative of 3 independent experiments with similar results.