Science advancesJul 17, 2026

A unique process of showing vaccine parts triggers strong T cell immune response in mRNA vaccines using lipid nanoparticles

mRNA Technology Weekly Brief ↗PubMed ↗DOI ↗

Updated Jul 19, 2026

Abstract

The number of antigen-specific CD8 T cells in mice immunized with mRNA-LNP was ten times higher than that induced by traditional vaccine methods.

mRNA-LNP vaccines trigger strong differentiation of cytotoxic CD8 T cells and stimulate antibody production.
Antigen presentation mechanisms of mRNA-LNP differ from those of conventional adjuvants, leading to unique immune responses.
The expansion of CD8 T cells induced by mRNA-LNP is potent and long-lasting.
Migratory type 2 conventional dendritic cells in draining lymph nodes primarily take up mRNA-LNPs.
Induction of CD8 T cells by mRNA-LNP relies on migratory dendritic cells rather than the traditional cross-presentation pathway.

Simplified

Lipid nanoparticle-encapsulated mRNA (mRNA-LNP) vaccines trigger the potent differentiation of antigen-specific cytotoxic CD8 T cells in addition to antibody production. Despite its high immunogenicity, the cellular mechanisms by which mRNA-LNP induces such unusual immune responses remain largely unclear. Here, we show that mRNA-LNP induces potent and long-lasting CD8 T cell expansion through an antigen presentation mechanism that differs from that of conventional adjuvants. In mice immunized with mRNA-LNP, the number of antigen-specific CD8 T cells was one order of magnitude higher than that induced by combining antigen proteins with immunostimulants such as lipopolysaccharide or polyinosinic:polycytidinic acid. Intramuscularly administered mRNA-LNPs were mainly taken up by migratory type 2 conventional dendritic cells in draining lymph nodes, resulting in notably strong and persistent antigen presentation through major histocompatibility complex class I. Furthermore, CD8 T cell induction by mRNA-LNP required migratory dendritic cells but not the traditional cross-presentation pathway that is otherwise essential for antiviral and antitumor immunity. Thus, the mRNA-LNP formulation exerts unconventional immune responses through a different antigen-presentation pathway from conventional component vaccines.