Codon optimized firefly luciferase was cloned into an mRNA production plasmid (optimized 3′ and 5′ UTR and containing a 101 polyA tail), in vitro transcribed in the presence in the presence of N1-methylpseudouridine modified nucleoside (N1mψ), co-transcriptionally capped using the CleanCap technology (TriLink) and cellulose purified to remove dsRNA. Purified mRNA was ethanol precipitated, washed, resuspended in nuclease-free water, and subjected to quality control (electrophoresis, dot blot, and transfection into human dendritic cells). mRNA was stored at −80°C until use32 (link).