IL-4 DC and IL-10 DC inhibit the proliferation of responsive T cells. IL-4 DC and IL-10 DC were unable to activate either naïve T cells in the mixed leukocytes culture (A) or antigen-specific T cells in the T-cell proliferation assay (B). The effect of mature S-DC on the proliferation of naïve T cells is shown in the inset of Fig. A. The antigen-specific restimulation of P1-specific T cells by P1-loaded S-DC (P1) is shown in B (inset). Different numbers of IL-4 DC and IL-10 DC influenced the S-DC-induced proliferation of antigen-specific T cells (C-D). The addition of P1-loaded IL-4 DC and IL-10 DC to the proliferation assay on day 2 of the 3-day culture prevented the marked increase in T-cell proliferation that had been induced by P1-loaded S-DC between days 2 and 3 (E-F). The results (mean ± standard deviation) shown are representative for 3 different experiments. Control: Naïve T cells (A) and antigen-specific T cells (B) cultured alone; ∅: P1-unloaded S-DC.