IFN-γ signaling regulates the expansion of memory CD8⁺ T cells.

<p>(A, B) IL-18 production from DCs. (A) DCs isolated from spleen of IFN-γR1^−/− and wild type mice were stimulated with LPS in the presence or absence of IFN-γ for 24 hr. (B) IFN-γR1^−/− and wild type mice were injected with PBS or anti-CD40 and 1hr later, DCs were isolated and cultured in the presence of LPS for 24 hr. The culture supernatants were harvested and IL-18 production was measured by ELISA. (C, D) IFN-γR1^−/− and wild type mice were primed with PBS or anti-DEC:OVA+anti-CD40, and boosted with anti-DEC:OVA+anti-CD40 at day 60. At day 0, 4, 5, and 7 after boosting, lymphocytes were isolated from spleen (C) and liver (D), and stained with Kb/OVA257-264 tetramer. (C and D)Percentage of tetramer⁺ cells in CD8⁺ T cells. (E) In vivo CTL activity. IFN-γRI^−/− 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.