IL-18 accumulates at the DC:T synapse and regulates CD8⁺ T cell proliferation.

<p>(A) OVA(257-264) peptide-pulsed or unpulsed DCs were cultured with OT-I transgenic CD8⁺ T cells, and stained with anti-IL-18 (green) and anti-CD11c (red). Nuclei were counterstained with DAPI (blue). (B, C) IL-18^−/− and wild type mice were primed with PBS or anti-DEC:OVA+anti-CD40, and boosted with anti-DEC:OVA+anti-CD40 at d 60. At day 0, 4, 5, and 7 after boosting, lymphocytes were isolated from spleen (B) and liver (C), and stained with Kb/OVA257-264 tetramer. (B and C) Percentage of tetramer⁺ cells in CD8⁺ T cells. (D) In vivo CTL activity. IL-18^−/− mice were primed with PBS, or anti-DEC:OVA+anti-CD40, without booster immunization. At d 60, CTL activity was determined by challenge with CFSE^hi OVA257-264 peptide-loaded splenocytes. Numbers indicate the % of specific killing. Representative of two experiments.