mRNA vaccines prime CD8+ T cells through two dendritic routes and cross-dressed MHC-I

Nature reports that mRNA–LNP vaccines prime CD8+ T cells not through the classic cDC1 cross-presentation, but via redundant input from both cDC1 and cDC2 dendritic cells; a substantial portion of priming comes from cross-dressing—peptide–MHC-I complexes transferred from non-hematopoietic cells in a type I interferon–dependent process—broadening T-cell activation to antigens not encoded by the vaccine and supporting anti-tumor immunity and memory.