The induction of anergic and regulatory properties of CD4⁺ T cells is dependent on type I IFNs and IL-10. (A) Naive CD4⁺ T cells were stimulated with allogeneic HSV-pDCs for 8 days in the presence of isotype-matched control mAb, anti-IFN-α/β receptor mAb, anti-IL-10 mAb, or a mixture of the both mAbs. Alternatively, T cells were stimulated with allogeneic GM-CSF–mDCs for comparison. The CD4⁺ T cells were harvested and restimulated with irradiated allogeneic CD3-depleted PBMCs. After 4 days, wells were pulsed for 16 hours with [³H] thymidine. (B) Naive CD4⁺ T cells were stimulated with allogeneic HSV-pDCs for 8 days in the presence of isotype-matched control mAb, anti-IFN-α/β receptor mAb, anti-IL-10 mAb, or a mixture of the both mAbs. Naive CD4⁺ T cells were stimulated with irradiated allogeneic CD3-depleted PBMCs in the absence or presence of the CD4⁺ T cells that had been stimulated with HSV-pDCs. After 4 days, wells were pulsed for 16 hours with [³H] thymidine. Error bars indicate SD. The data shown are representative of 3 experiments.