Inhibitory effects of IL-10–pretreated DC on alloantigen-or anti-CD3–induced proliferation of naive CD8⁺ T cells: dependence on the state of maturation of DC. DC were generated from peripheral progenitors as described above, resuspended at day 7, and stimulated with IL-1β, IL-6, TNF-, and PGE₂ to induce and stabilize the maturation of the DC. IL-10 was added for the last 2 days of culture at various time points after the stimulation: simultaneous additon at day 7 and harvested of the DC at day 9 (A and B) or addition at a later stage of maturation (day 10) and subsequently harvest at day 12 (C and D) . Control and IL-10–treated DC were cocultured with naive CD45 RA⁺/CD8⁺ T cells (2 × 10⁵) in allogeneic MLR (A and C) or anti-CD3 assays (B and D). Proliferation was measured by [³H] TdR uptake. The results are representative of five experiments.