Regulation of spontaneous DC death. Immediately after maturation, human monocyte-derived DCs were cultured for 4 days in the presence or absence of 100 μM z-VAD.fmk added every day (A) or culture medium supplemented every 2 days with 800 U/ml GMCSF and 100 U/ml IL-4 (B). Aliquots of cells were collected every day (0, 1, 2, 3 or 4 days of culture) for determination of Δψm (DiOC6(3) staining) and cell death (PI uptake). Mean ± S.D. from 5 independent experiments are shown. (C) Effects of maturation factors on spontaneous DC death. DCs were induced to mature by the addition of 1 μg/ml LPS for 18 hrs or 10 μg/ml poly (I:C) or 5 μg/ml anti-CD40 mAb and then mature DCs cultured for 4 days, with an aliquot of cells collected every day (0, 1, 2, 3 or 4 days of culture) for determination of Δψm (DiOC6(3) staining) and cell death (PI uptake). Mean ± S.D. from five independent experiments are shown.