TLR stimulation and CD4 help license DC to prime CD8⁺ T cells. (A-B) Autologous naive CD4⁺ or CD8⁺ T cells from peripheral blood were CFSE-labeled and cultured alone or together with allogeneic DC or monocytes subsets in the absence (−) or presence of TLR agonists as indicated. Proliferation was assessed after 7 days by CFSE dilution and is shown as the percentage of divided CD4⁺ T cells (A) or CD8⁺ T cells (B). (C) MHC class I (upper panels) and CD86 (lower panels) expression on DC before (filled histograms) or after stimulation (open histograms) with LPS + R848 of mDC1 (left panels), with polyI:C + R848 of mDC2 (central panels) and with CpG of pDC (right panels). One representative donor of 3 is shown. *P < .05; **P < .005; ***P < .0005.