Figure 4.

Type I IFN Signaling on T Cell Enhances the Overall Outcome of the T Cell Response upon i.v. Delivery of mRNA-Lipoplexes

CD11c-Cre^+/−IFNAR^fl/fl and CD4-Cre^+/−IFNAR^fl/fl mice were immunized i.v. with 10 μg CleanCap OVA mRNA-lipoplexes (DOTAP/DOPE or RNAiMAX). Two weeks after the last immunization, the induced T cell responses were determined. (A and B) Spleens were isolated and in vitro stimulated with OVA peptide for 16 h. (A) The number of OVA-specific IFN-γ-secreting splenocytes was determined by an ELISpot. Data represent individual mice and the mean (four or five mice per group). (B) Functionality of OVA-specific T lymphocytes was measured by flow cytometry using intracellular staining for IFN-γ. Data represent individual mice and mean +/− SD (four or five mice per group). (C) A mixture of CFSE-labeled cells pulsed with control (CFSE^low) or OVA peptide (CFSE^high) was adoptively transferred in a 1:1 ratio to mRNA-lipoplex-immunized mice (i.v. route). Specific killing was measured 2 days later by flow cytometry. Data represent individual mice and the mean +/− SD (four or five mice per group).