Curdlan acts as an adjuvant for CTL crosspriming in vivo. C57Bl/6 mice were immunized in both hind footpads with OVA protein alone (none) or together with curdlan or polyI:C as indicated. Target cells were injected 6 days later and mice were analyzed on day 7. (A) H-2K^b-SIINFEKL tetramer staining of splenocytes. Left: representative dot plots of tetramer staining vs CD8 in gated Thy1.2⁺ T cells. Numbers indicate percent of tetramer⁺ cells. Right: frequency of tetramer⁺ CD8⁺ T cells (gated on scatter and Thy1.2⁺ cells). Individual mice from 2 pooled experiments are shown. (B) In vivo CTL activity measured by target cell elimination. Histograms show target cell frequency in representative mice from each group (CFSE^lo, 20 nM peptide, CFSE^int, 200 nM peptide, CFSE^hi, no peptide). Graph shows mean plus or minus SD of percent specific lysis from 2 pooled experiments. (C) In vitro restimulation with SIINFEKL peptide or in medium alone. IFN-γ content in supernatants at the end of the 2-day culture. Restimulations and ELISA measurements were done in triplicates. Data are the mean plus SD of the indicated number of mice in 2 pooled experiments. (D) Specific CTL activity of cells restimulated for 5 days in vitro. Effectors were used at different dilutions as indicated. Individual mice from 2 pooled experiments are shown.